Do you need to double cleanse tonight? Not automatically. It depends on which sunscreen you wore and how you wash, and there’s actual lab data on exactly this: researchers measured how much sunscreen stays on skin after different cleansing methods. Tell the checker what you used and it answers with those measurements, not a routine someone is trying to sell you.
Tonight’s cleansing check
“Not sure” is treated as water-resistant, the safer assumption. The label will say “water resistant” or list a 40 or 80 minute rating if it is.
The data behind the verdict
The numbers come from a 2020 study in the Journal of Cosmetic Dermatology that measured leftover sunscreen after washing [1]. Water alone left about 54% of a regular sunscreen and 59% of a water-resistant one still on the skin. A regular cleanser got a regular sunscreen down to about 16% left, which is why one cleanse is a reasonable nightly routine for everyday SPF. The gap shows up with water-resistant formulas: a regular cleanser still left about 37%, while a cleansing oil brought it down to about 6%. That’s the case for adding the oil step on water-resistant days, and skipping the drama on ordinary ones. One precision note: the study measured each method on its own, so the oil figures are for oil alone. Follow the oil with your regular cleanser, the usual double-cleanse order, and you remove at least as much as the number shown.
| Cleansing method | Regular sunscreen left | Water-resistant left |
|---|---|---|
| Water only | about 54% | about 59% |
| Regular cleanser | about 16% | about 37% |
| Cleansing oil (measured on its own in the study) | about 13% | about 6% |
For the full walkthrough of why sunscreen clings, what the film-formers are doing, and how to do the oil step without overdoing it, read our guide to removing sunscreen. Not sure whether your sunscreen counts as water-resistant? The water resistance guide explains what those 40 and 80 minute labels legally mean.
Sources
[1] Chen et al., The optimal cleansing method for the removal of sunscreen, Journal of Cosmetic Dermatology 2020 (residual sunscreen after water only, cleanser, and cleansing oil, for regular and water-resistant formulas): link