Homemade Sunscreen: What the Recipes Claim vs What the Labs Measured

Type “homemade sunscreen” into Google and the autocomplete finishes the sentence for you: recipe, with zinc oxide, for face. Most recipes come with a number attached, SPF 20 here, SPF 30 there. What is harder to find is anyone who made one and put it under a lab instrument. A few research groups have, and this article is about what they measured. It is not a how-to. It is about where the numbers come from, and what happened when someone checked.

The recipe says SPF 20. Where does that number come from?

Start with the recipe that ranks near the top of the search results. Wellness Mama’s version calls for “2 TBSP non-nano zinc oxide powder” and explains the math plainly: “This recipe uses about 10% zinc oxide which is roughly a 6-11 SPF.” Then: “If you want an SPF of around 20, then double the zinc oxide.” And, to the author’s credit: “Keep in mind it hasn’t been tested by a regulatory organization for exact SPF.”^[9]

Another first-page recipe, from Don’t Waste the Crumbs, publishes a conversion chart: “For SPF 2-5: Use 5% zinc oxide,” “SPF 6-11: Use 10% zinc oxide,” “For SPF 12-19: Use 15% zinc oxide,” “SPF 20+: Use 20% zinc oxide.” The ingredient line reads “1 oz zinc oxide for about 20 SPF (2 Tbsp),” and the author notes that “this isn’t FDA-approved or tested, but it’s a good estimate.”^[10]

So the SPF in these recipes is a percentage of zinc oxide run through a chart. Nobody measured anything, and both authors say so. The SPF on a bottle is a test result; this is a different kind of number.

How common is the pattern? A 2025 review in the Journal of Integrative Dermatology tallied the ingredients and SPF claims in the top 50 Google results for homemade sunscreen recipes, blogs and videos together. Non-nano zinc oxide appeared in all 50, with a mean claimed SPF of 18.3 and a range from 2 to 50. Coconut oil was in 49 of 50 (mean claim 5.2), shea or cocoa butter in 46 (5.7), carrot seed oil in 25 (37.4), and red raspberry seed oil in 14 (39.9).^[12] On the zinc math: “Internet users have several formulas they use in order to estimate the percentage of zinc oxide correlating to a value of SPF; however, no studies have been published to back up these values.”^[12] It is a tally of claims, not measurements, and the journal is new, so we use it only for what it counted.

The pattern predates Google’s current results. In a study published in 2019, researchers at Nationwide Children’s Hospital and the University of North Florida sampled every fifth Pinterest pin for homemade and natural sunscreen, 189 pins in all. From the abstract: “the majority of pins (95.2%) positively portrayed the effectiveness of homemade sunscreens and 68.3% recommended recipes for homemade sunscreens that offered insufficient UV radiation protection. Sun Protection Factor (SPF) claims were made in 33.3% of pins with a range of SPF 2 to SPF 50.”^[1] The hospital’s press release added the reach: “The average number of saves for a pin was 808, with one pin being saved more than 21,700 times.”^[2]

Nearly all of these recipes specify non-nano zinc oxide, which the blogs treat as the safer grade. We went through the regulators’ findings on that in nano vs non-nano zinc oxide. Particle size does not change the fact that the SPF was never measured.

A lab made 15 homemade sunscreen recipes. Here is what it measured

A study often cited when people say homemade sunscreen doesn’t work is from the pharmacy faculty at the University of Nantes, published in the Journal of Cosmetic Dermatology in 2021 (online in late 2020). The method, from the abstract: “Fifteen Internet recipes were chosen, and then, the products were made in the laboratory following the protocols described. Using an in vitro method, the following efficacy indicators were determined for the preparations made: the Sun Protection Factor (SPF), the Production Factor in the UVA domain (PF-UVA), and the critical wavelength.”^[3]

The result, also verbatim: “Three of the 15 recipes studied do not contain any sunscreen and therefore constitute a major risk for users in case of exposure to the sun. The other 12 cannot be considered as sun protection products since all of them have an SPF under 6, the threshold value required in Europe.”^[3] The conclusion calls the recipes “very dangerous since some of them have no photoprotective effect whatsoever and most of them do not ensure a sufficient level of photoprotection.”^[3]

Three out of fifteen had no filter at all. The other twelve did contain zinc oxide or something like it, and still came in under 6. The abstract gives no lower number and the full table is paywalled, so we print none of our own. Two secondhand figures exist, and they disagree slightly. Consumer Reports, summarizing the study in 2021, wrote that “The other 12 recipes tested ranged from SPF 1.5 to SPF 6.”^[5] The authors themselves, on a cosmetics-industry blog in June 2026, said they “tested about fifteen homemade recipes in our pharmacy-faculty laboratory, demonstrating their poor effectiveness, with in vitro SPFs ranging from 1 to 5.”^[4] Whichever you take, the ceiling is the same. On the “required in Europe” phrase, the authors’ own framing is “under European recommendations, a product with an SPF below 6 cannot be called a sun-protection product,”^[4] a labeling convention rather than a ban.

A systematic review in JMIR Dermatology in July 2026 landed in the same place: “homemade sunscreens may have an SPF as high as 6, with some providing no SPF at all,” and, in sum, “homemade sunscreens offer little to no sun protection.”^[13]

What the recipes claim vs what the labs measured

The whole argument in one table: what recipes and blogs say on the left, what a lab measured on the right. Read the method column, because the numbers come from four different kinds of test and are not interchangeable.

Recipe or ingredient	What the recipe or blog claims	What the lab measured	Method
10% zinc oxide recipe (Wellness Mama)	“roughly a 6-11 SPF”[9]	No significant reduction in sunburn cells; “virtually no absorbance in the UVA range”[8]	Human skin samples (ex vivo). SPF itself was not measured
20% zinc oxide, 1 oz per batch	“about 20 SPF”[10]	No published study supports the zinc-to-SPF conversion[12]	None exists
15 internet recipes, made as written	Various	3 contained no UV filter; the other 12 had “an SPF under 6”[3]	In vitro, plate
Coconut oil	Mean claim 5.2 (range 4-7) across 49 of 50 recipes[12]; the 2010 paper blogs cite said “around 8”[11]	0.0 in vitro and 1.2 on human skin[6]; 0.57 ± 0.01 on a plate[7]	Dilution method and human ISO test (2021); PMMA plate at 1.3 mg/cm² (2026)
Red raspberry seed oil	Mean claim 39.9 (range 25-50) across 14 of 50 recipes[12]	0.4 in vitro and 2.6 on human skin[6]; 0.64 ± 0.01 and 0.96 ± 0.03 for two samples on a plate[7]	Same as above
Carrot seed oil	Mean claim 37.4 (range 35-40) across 25 of 50 recipes[12]	0.1 in vitro and 2.5 on human skin[6]; 0.63 ± 0.04 on a plate[7]	Same as above
Shea butter	Mean claim 5.7 (range 4-6) across 46 of 50 recipes[12]	0.87 ± 0.01 refined, 0.99 ± 0.06 raw[7]	PMMA plate (2026)
Tamanu oil	Not in the top-50 tally	11.2 in vitro[6]; 21.50 ± 4.95 on a plate, falling to 5.2 after a photostability test[7]	Dilution method (2021); PMMA plate (2026)
Commercial “natural” mineral sunscreens labeled SPF 50	SPF 50 on the label	2.3 and 1.3 for two products[7]	PMMA plate (2026). Store-bought, not homemade

About those methods. The dilution method dissolves a little oil in alcohol and reads it in a spectrophotometer; it is the test behind many of the high oil numbers you see quoted. The plate method spreads a measured film on a roughened PMMA plate, here at 1.3 mg/cm², and reads transmission; the 2026 figures are the unadjusted readings. The human ISO test is what the SPF on a real bottle is based on. The skin sample study did not measure SPF at all; it counted damaged cells, which is why that row has no number.

The oil myth: coconut, raspberry seed, carrot seed

If you have seen “coconut oil has SPF 7” in a recipe, the source is often a 2010 paper in Pharmacognosy Research from a pharmacy institute in India. It made “hydroalcoholic dilutions of oils,” read them in a spectrophotometer between 290 and 320 nm, and reported that “the SPF value of olive oil and coconut oil was found to be around 8; castor oil, around 6; almond oil, around 5; mustard oil and chaulmoogra oil, around 3; and sesame oil, around 2.”^[11] That paper has been copied into recipe blogs for years.

In 2021 a team split between Slovakia and the Czech Republic tested 14 virgin vegetable oils two ways: the same dilution method, done strictly to the original protocol, and a human ISO test in a second lab. For the five most promoted oils, carrot seed, coconut, raspberry seed, rosehip seed and wheat germ, the abstract reports “SPF values in vitro (0.1; 0.0; 0.4; 0.2 and 0.2) and in vivo (2.5; 1.2; 2.6; 2.6; and 2.8),” which “were significantly lower than the values reported in the controversial studies.”^[6] Then: “We have shown that the overestimated SPF values of these oils were determined by authors who did not strictly follow Mansur’s original methodology.”^[6] They also warn against reading too much into the tiny in vitro figures: “An SPF value of less than 1, which can be determined by this Mansur’s method, is physiologically impossible and meaningless.”^[6] So the honest number for coconut oil on human skin is 1.2, not 0 and not 8.

A 2026 paper from Jagiellonian University in Poland ran the plate method on 11 oils and butters and got the same shape of answer: coconut oil 0.57 ± 0.01, carrot seed oil 0.63 ± 0.04, two raspberry seed oils at 0.64 ± 0.01 and 0.96 ± 0.03, shea butter 0.87 and 0.99.^[7] Its conclusion is one sentence: “plant oils do not provide adequate photoprotection and cannot replace conventional UV filters.”^[7]

That leaves the SPF 30 to 50 claims for carrot seed and raspberry seed oil. Those come from the recipes: the 2025 tally found mean claimed SPFs of 37.4 and 39.9 across the blogs that used them.^[12] The labs got 2.5 and 2.6 on skin, and under 1 on a plate. The 2026 paper notes that claims of “SPF values reaching up to 50” circulate for these oils, “often citing SPF values up to 22 based on in vitro spectrophotometric measurements of dilute solutions.”^[7]

One oil is the exception, and it is instructive. Tamanu oil measured 11.2 in the 2021 dilution test, the only vegetable oil the authors said was “worth mentioning,” and 21.50 ± 4.95 on the 2026 plate.^[6][7] Then the Polish team exposed it to light and measured again: “its in vitro SPF decreased to 5.2 after photostability testing.”^[7] The one natural oil with a real number lost most of it in the sun, which is the problem formulated sunscreens solve with stabilizers and filter combinations; we explained what each filter does in Korean sunscreen filters, explained.

The one recipe someone actually put on human skin

Everything above is plates and solutions. In 2025 a group at the University of Sydney made the Wellness Mama recipe, the one in the table above, and tested it on human skin.^[8]

The composition they list is “almond oil … 39% (v/v), coconut oil … 10% (v/v), white beeswax pellets … 19% (v/v), non-nano uncoated zinc oxide powder … 10% (w/v), shea butter … 10% (v/v), red raspberry seed oil … 1.6% (v/v)” plus carrot seed oil at 1.6%.^[8] They applied it to skin samples donated by three patients, all Fitzpatrick type I, and compared it against a commercial SPF 50+ sunscreen under UV. This is ex vivo work, living skin outside the body, and it does not produce an SPF rating. It produces a count of what UV did to the cells.

First, the optics. The homemade cream showed “relatively low absorbance in the UVB range (280–320 nm) and virtually no absorbance in the UVA range (320–400 nm).”^[8] A 10% zinc oxide dispersion stirred in a kitchen is not the same material as a formulated mineral sunscreen.

Then the cells. Sunburn cells are skin cells that have died from UV damage, and pathologists count them. The commercial SPF 50+ product cut sunburn cells “from 100% to 8.5 ± 3.7%” relative to unprotected skin. The homemade cream “did not display a significant reduction”: 55.2 ± 21.7% when freshly made, and 72.7 ± 16.2% after three weeks on the shelf.^[8] The stored batch did worse than the fresh one.

One result went the other way and we are not going to hide it. On cyclobutane pyrimidine dimers, a marker of direct UV damage to DNA, unprotected skin scored 79.4%, the SPF 50+ product 44.0%, and the homemade cream 57.1% fresh and 54.5% stored, with “no significant differences between NHSS1D and NHSS3W and the SPF50+” on that measure.^[8] Three donors is a small study, and on this marker the gap did not reach significance. The abstract states both halves in one sentence: the homemade creams “can reduce UVR-induced DNA damage and epidermal thickness, but do not effectively protect against the generation of sunburn cells.”^[8] The recommendation that follows is “the continued use of TGA-approved commercial sunscreens for sun protection.”^[8]

The authors are careful about the blogger, and so are we: “Although the wellness blogger did not claim that this NHSS provided high SPF, its use was implicitly recommended as an alternative to regular SPF50+ sunscreen.”^[8] And on the bigger question: “there is as yet no evidence for NHSSs in prevention of skin carcinogenesis.”^[8] NHSS is their abbreviation for natural homemade sunscreen. The conflict-of-interest statement reads “None.”

Why a kitchen can’t produce an SPF number

American regulators treat sunscreen as a nonprescription drug. The FDA’s consumer page opens with it: “Just as it does with other nonprescription drug products, FDA regulates sunscreens to ensure they meet safety and effectiveness standards.”^[16] And it defines the number: “All sunscreens must be tested to measure the amount of ultraviolet (UV) radiation exposure it takes to cause sunburn when using the sunscreen compared to how much UV exposure it takes to cause a sunburn when not using the sunscreen.”^[16] SPF is the ratio of those two doses, measured on people, and a zinc-to-SPF chart skips that step. (We checked the FDA page for any mention of homemade sunscreen. There is none, so nothing here should be read as an FDA statement on recipes.)

The professional bodies have addressed recipes directly. The American Academy of Dermatology said in a July 2024 statement that research shows most homemade sunscreens “lack effective sun protection, leaving users vulnerable to sunburn, premature skin aging and skin cancer,” and that “due to inconsistencies in consumer preparation, the efficacy of homemade sunscreens may also vary between batches, putting users at risk for skin cancer.”^[14] A dermatologist quoted by the Skin Cancer Foundation put the precision problem this way: “Even if you do include effective UV filters like zinc oxide, it’s impossible to create a product with the level of precision required.”^[15]

Why precision? Because zinc oxide works as a film of particles, and what that film does depends on how evenly the particles are dispersed, how thick the layer is, and whether it stays put. The clearest illustration is not a homemade recipe at all. The same 2026 Polish study also tested nine commercial sunscreens marketed as “natural,” alongside three conventional ones, all bought in stores. Two products labeled SPF 50, both listing zinc oxide among their ingredients, measured 2.3 and 1.3 on the plate. A product labeled SPF 25 with non-nano zinc oxide measured 7.9.^[7] These were factory products, from Poland, Bulgaria, India and France, none Korean, and the factories still could not make the label number from zinc alone. One product in the same set, with titanium dioxide second on its ingredient list, measured 64.2.^[7] Same filter family, different formulation, different result.

Even tested SPF numbers move between laboratories, as we showed in can you trust Korean SPF labels. If a measured number can drift between labs, a number that was never measured has nothing holding it in place.

If “natural” is what you want

Most people who search for a homemade sunscreen recipe want fewer ingredients, a filter they recognize, and a company that says what is in the tube. Those are fair things to want, and you can get all three without the kitchen. A sunscreen that uses only zinc oxide or titanium dioxide is what the recipes are trying to approximate; the difference is that a manufactured one has been through the human test described above. A few places to start on this site:

• Our reef-safe sunscreen myth piece covers a Korean sunscreen that uses zinc oxide as its only filter, and takes apart the idea that a “reef-safe” badge means harmless, the same instinct that makes a kitchen recipe feel safe.
• The SKIN1004 Air-Fit review is a tested zinc oxide and titanium dioxide formula with no chemical filters. Read it before buying, because it has its own trade-offs (it contains plant oils and is not fragrance free), and that article goes through them.
• The sensitive and acne-prone skin guide has one zinc oxide pick for reactive skin (Dr.G Green Mild Up) alongside four modern chemical-filter picks, and explains why “sensitive means mineral” is no longer a rule.
• If the words are the confusing part, organic vs inorganic sunscreen explains why “inorganic” is the technical term for mineral.

On the number to aim for: the AAD’s 2024 statement recommends “a broad-spectrum, water-resistant sunscreen with an SPF of 30 or higher.”^[14] We compared 30 against 50 in SPF 30 vs SPF 50. Either of those is a tested number. The recipes top out, when measured, under 6.

FAQ

Does coconut oil have SPF?

Barely, and the answer depends on how it was measured. A 2010 dilution study reported coconut oil at “around 8.”^[11] A 2021 study that ran the dilution method strictly and added a human ISO test got 0.0 in vitro and 1.2 on human skin, and concluded the earlier high values came from authors who “did not strictly follow Mansur’s original methodology.”^[6] A 2026 plate test measured coconut oil at 0.57 ± 0.01.^[7] The number measured on people is 1.2, which is another way of saying it is not a sunscreen.

How much zinc oxide do I need for SPF 30 in homemade sunscreen?

There is no amount that gets you a known SPF 30, because the zinc-to-SPF charts in recipes were never validated. The 2025 review that tallied the top 50 online recipes states that “no studies have been published to back up these values.”^[12] Zinc oxide does work as a UV filter, but how well a cream works depends on dispersion and film thickness, not just the percentage, which is why two store-bought “natural” zinc products labeled SPF 50 measured 2.3 and 1.3 in a 2026 plate test.^[7] The 15 internet recipes a French lab made and measured all came in “under 6,” and three had no filter at all.^[3]

Is homemade sunscreen safe for babies and kids?

No published test supports using one. Of the 15 recipes measured in the Nantes study, three contained no UV filter, and Consumer Reports noted that those three included “one the original poster recommended especially for use on children.”^[3][5] The American Academy of Dermatology’s 2024 statement describes homemade sunscreens as leaving “users vulnerable to sunburn, premature skin aging and skin cancer.”^[14] For children the usual advice is shade, clothing, and a tested sunscreen, and we listed the ones we would consider in Korean sunscreen for kids and babies. If a recipe has already caused a rash, the plant and essential oils in it are the usual suspects rather than the zinc, and sunscreen breakouts and irritation covers what to look for.

We’re not doctors or dermatologists, and none of this is medical advice. If you or your child has had a bad burn, a reaction to a homemade cream, or a history of skin cancer, that is a conversation for a physician rather than a blog post.

Sources:
[1] Merten JW, Roberts KJ, King JL, McKenzie LB. Pinterest Homemade Sunscreens: A Recipe for Sunburn. Health Commun. 2020;35(9):1123-1128 (online 2019). PMID 31111735. DOI 10.1080/10410236.2019.1616442. Source for the sampling method (“sampled every fifth pin to collect 189 relevant pins”) and for the figures quoted: 95.2% positively portrayed effectiveness, 68.3% recommended recipes offering insufficient protection, SPF claims in 33.3% of pins ranging from SPF 2 to SPF 50. We read the abstract; the full text is paywalled, so no recipe-ingredient figures are attributed to this paper. https://pubmed.ncbi.nlm.nih.gov/31111735/
[2] Nationwide Children’s Hospital. Pinterest Homemade Sunscreens: A Recipe for Sunburn. Press release, May 20, 2019. Source for “The average number of saves for a pin was 808, with one pin being saved more than 21,700 times.” https://www.nationwidechildrens.org/newsroom/news-releases/2019/05/pindiy-sunscreen-safety-study
[3] Couteau C, Dupont C, Paparis E, Coiffard LJM. Demonstration of the dangerous nature of ‘homemade’ sunscreen recipes. J Cosmet Dermatol. 2021;20(6):1788-1794 (online November 2020). PMID 33047478. DOI 10.1111/jocd.13783. Université de Nantes. Source for the method (15 internet recipes made in the laboratory, in vitro SPF, PF-UVA and critical wavelength), for “Three of the 15 recipes studied do not contain any sunscreen,” for “all of them have an SPF under 6, the threshold value required in Europe,” and for “no photoprotective effect whatsoever.” We read the abstract; the full text and its recipe-by-recipe table are paywalled, which is why we quote no lower bound from this paper and attribute the “1.5 to 6” and “1 to 5” ranges to references [5] and [4] respectively. https://pubmed.ncbi.nlm.nih.gov/33047478/
[4] Couteau C, Coiffard L. My Homemade Sunscreen? NO! Technature blog, June 3, 2026. Written by two authors of reference [3]. Source for “we tested about fifteen homemade recipes in our pharmacy-faculty laboratory, demonstrating their poor effectiveness, with in vitro SPFs ranging from 1 to 5” and for “under European recommendations, a product with an SPF below 6 cannot be called a sun-protection product.” https://www.tech-nature.com/en/blog/my-homemade-sunscreen-no
[5] Wadyka S. Homemade Sunscreen Is a Definite Don’t. Consumer Reports, updated May 30, 2021. Source for “The other 12 recipes tested ranged from SPF 1.5 to SPF 6” (Consumer Reports’ figure, not in the study abstract) and for the note that the three filter-free recipes included “one the original poster recommended especially for use on children.” https://www.consumerreports.org/sunscreens/homemade-sunscreen-is-a-definite-dont-a6318213159/
[6] Ácsová A, Hojerová J, Janotková L, Bendová H, Jedličková L, Hamranová V, Martiniaková S. The real UVB photoprotective efficacy of vegetable oils: in vitro and in vivo studies. Photochem Photobiol Sci. 2021;20(1):139-151. PMID 33721242. DOI 10.1007/s43630-020-00009-3. Fourteen virgin vegetable oils tested by the Mansur dilution method in Slovakia and by the ISO in vivo method in the Czech Republic. Source for the in vitro values (0.1; 0.0; 0.4; 0.2; 0.2) and in vivo values (2.5; 1.2; 2.6; 2.6; 2.8) for carrot seed, coconut, raspberry seed, rosehip seed and wheat germ oils in that order, for “the overestimated SPF values of these oils were determined by authors who did not strictly follow Mansur’s original methodology,” for tamanu oil at 11.2 being the only value “worth mentioning,” and for “An SPF value of less than 1, which can be determined by this Mansur’s method, is physiologically impossible and meaningless.” https://pubmed.ncbi.nlm.nih.gov/33721242/
[7] Popiół-Adamska J, Kolisz M, Pękala E, Gunia-Krzyżak A. Natural photoprotection under scrutiny: an in vitro evaluation. Photochem Photobiol Sci. 2026;25(6):1145-1153 (online May 2026). PMID 42084842. DOI 10.1007/s43630-026-00911-2. Jagiellonian University. Eleven oils and butters and twelve commercial sunscreens (nine marketed as “natural,” three conventional) on PMMA plates at 1.3 mg/cm², SPF Analyzer 290AS; we read the full text. Source for the unadjusted in vitro SPF values quoted: coconut oil 0.57 ± 0.01, fractionated coconut oil 0.54 ± 0.10, refined sweet almond oil 0.58 ± 0.01, carrot seed oil 0.63 ± 0.04, raspberry seed oils 0.96 ± 0.03 and 0.64 ± 0.01, refined shea butter 0.87 ± 0.01, raw shea butter 0.99 ± 0.06, tamanu oil 21.50 ± 4.95 and “its in vitro SPF decreased to 5.2 after photostability testing”; for the commercial products (two labeled SPF 50 measuring 2.3 and 1.3, one labeled SPF 25 measuring 7.9, one titanium dioxide product measuring 64.2); for the introduction’s description of claims “reaching up to 50” and “often citing SPF values up to 22 based on in vitro spectrophotometric measurements of dilute solutions”; and for the conclusion “plant oils do not provide adequate photoprotection and cannot replace conventional UV filters.” The commercial products were made in Poland, Bulgaria, India and France; none is Korean and none is homemade. https://pubmed.ncbi.nlm.nih.gov/42084842/
[8] Ince FA, Nayar JC, Wong AL, McClelland JA, Holland AJA, Stern H, Abboud M, Mason RS, Dixon KM. Uncovering the efficacy of a natural homemade sunscreen in protection from ultraviolet radiation. Photochem Photobiol Sci. 2025;24(6):1017-1029. PMID 40481984. DOI 10.1007/s43630-025-00742-7. University of Sydney; we read the full text. Ex vivo human skin explants from three donors, Fitzpatrick type I; the recipe is cited to wellnessmama.com. Source for the composition quoted, for “relatively low absorbance in the UVB range (280–320 nm) and virtually no absorbance in the UVA range (320–400 nm),” for sunburn cells falling “from 100% to 8.5 ± 3.7%” with the SPF 50+ product while the homemade cream “did not display a significant reduction” (55.2 ± 21.7% fresh, 72.7 ± 16.2% after three weeks), for the CPD figures (79.4%, 44.0%, 57.1%, 54.5%) and “no significant differences between NHSS1D and NHSS3W and the SPF50+,” for “Although the wellness blogger did not claim that this NHSS provided high SPF, its use was implicitly recommended as an alternative to regular SPF50+ sunscreen,” for “there is as yet no evidence for NHSSs in prevention of skin carcinogenesis,” for the abstract’s summary that NHSSs “can reduce UVR-induced DNA damage and epidermal thickness, but do not effectively protect against the generation of sunburn cells” and its recommendation of “the continued use of TGA-approved commercial sunscreens for sun protection,” and for the conflict-of-interest statement “None.” This study did not measure SPF, and we attribute no SPF value to it. https://pubmed.ncbi.nlm.nih.gov/40481984/
[9] Wells K. Natural Homemade Sunscreen Recipe. Wellness Mama, read 2026-08-21. Source for “2 TBSP non-nano zinc oxide powder,” “This recipe uses about 10% zinc oxide which is roughly a 6-11 SPF,” “If you want an SPF of around 20, then double the zinc oxide,” and “Keep in mind it hasn’t been tested by a regulatory organization for exact SPF.” This is the recipe tested in reference [8]. https://wellnessmama.com/beauty/homemade-sunscreen/
[10] Don’t Waste the Crumbs. Easy 3-Ingredient Homemade Sunscreen. Read 2026-08-21. Source for “1 oz zinc oxide for about 20 SPF (2 Tbsp),” the conversion chart (“For SPF 2-5: Use 5% zinc oxide,” “SPF 6-11: Use 10% zinc oxide,” “For SPF 12-19: Use 15% zinc oxide,” “SPF 20+: Use 20% zinc oxide”), and “this isn’t FDA-approved or tested, but it’s a good estimate.” https://dontwastethecrumbs.com/homemade-sunscreen/
[11] Kaur CD, Saraf S. In vitro sun protection factor determination of herbal oils used in cosmetics. Pharmacognosy Res. 2010;2(1):22-25. PMID 21808534. DOI 10.4103/0974-8490.60586. PMCID PMC3140123. Mansur dilution method, 290-320 nm. Source for “Hydroalcoholic dilutions of oils were prepared” and for “the SPF value of olive oil and coconut oil was found to be around 8; castor oil, around 6; almond oil, around 5; mustard oil and chaulmoogra oil, around 3; and sesame oil, around 2.” This is the paper reference [6] describes as not following the original methodology strictly. https://pubmed.ncbi.nlm.nih.gov/21808534/
[12] Arkhipenko Z, Shah SC, Yi RC, Feldman SR. A Review on Homemade Sunscreen. J Integr Dermatol. 2025. DOI 10.64550/joid.yz1h1125. Open access; we read the full text. Table 2 tallies ingredients and SPF claims “based on the top 50 Google search results from relevant blogs and social media platform videos.” Source for non-nano zinc oxide in 50 of 50 recipes (mean claimed SPF 18.3, range 2-50), coconut oil 49 (5.2, range 4-7), shea or cocoa butter 46 (5.7, range 4-6), carrot seed oil 25 (37.4, range 35-40), red raspberry seed oil 14 (39.9, range 25-50), and for “Internet users have several formulas they use in order to estimate the percentage of zinc oxide correlating to a value of SPF; however, no studies have been published to back up these values.” These are claimed values collected from recipes, not measurements. The journal is recently established, and we rely on this paper only for its tally. https://jintegrativederm.org/doi/10.64550/joid.yz1h1125
[13] Kaftan G, Panillo M, Maxon L, Esposito E. The Rise in Homemade Sunscreen Trends and Future Impacts on Skin Cancer Risk: Systematic Review. JMIR Dermatol. 2026;9:e84694. PMID 42398033. DOI 10.2196/84694. PMCID PMC13331330. Source for “homemade sunscreens offer little to no sun protection” and “homemade sunscreens may have an SPF as high as 6, with some providing no SPF at all.” https://pubmed.ncbi.nlm.nih.gov/42398033/
[14] American Academy of Dermatology. American Academy of Dermatology warns that homemade sunscreens are not proven to be effective and may leave users vulnerable to skin cancer. Press release, July 2, 2024. Source for “lack effective sun protection, leaving users vulnerable to sunburn, premature skin aging and skin cancer,” for “due to inconsistencies in consumer preparation, the efficacy of homemade sunscreens may also vary between batches, putting users at risk for skin cancer,” and for the recommendation to “apply a broad-spectrum, water-resistant sunscreen with an SPF of 30 or higher to all skin not covered by clothing.” https://www.aad.org/news/homemade-sunscreens-not-effective
[15] Skin Cancer Foundation. Ask the Expert: Is Homemade Sunscreen Safe? Blair Murphy-Rose, MD. July 30, 2024. Source for “Even if you do include effective UV filters like zinc oxide, it’s impossible to create a product with the level of precision required.” https://www.skincancer.org/blog/is-homemade-sunscreen-safe/
[16] US Food and Drug Administration. Sunscreen: How to Help Protect Your Skin from the Sun. Content current as of June 9, 2026. Source for “Just as it does with other nonprescription drug products, FDA regulates sunscreens to ensure they meet safety and effectiveness standards” and for “All sunscreens must be tested to measure the amount of ultraviolet (UV) radiation exposure it takes to cause sunburn when using the sunscreen compared to how much UV exposure it takes to cause a sunburn when not using the sunscreen.” The page does not mention homemade sunscreen. The live fda.gov URL returned an access-blocked page to our requests, so we link the Internet Archive snapshot we read (August 8, 2026). https://web.archive.org/web/20260808110824/https://www.fda.gov/drugs/understanding-over-counter-medicines/sunscreen-how-help-protect-your-skin-sun

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