What does your sunscreen actually cost per month? Not the sticker price, the real number: price divided by how long the bottle lasts at a proper dose. Most people have never done this math, and it flips a few assumptions. A $16 bottle used correctly on face and neck runs out in weeks, not months, and a bottle that lasts half a year usually means the dose was never right in the first place.
Cost per month, at a real dose
Zone amounts follow the public health teaspoon guidance used in our amount calculator: about one teaspoon (5 ml) per zone. Prices vary by retailer and sale, so plug in what you actually paid.
The math, and what it tells you
The dose numbers are the same ones behind our amount calculator: about one teaspoon, roughly 5 ml, for face, neck and ears, scaling up to about 35 ml for a full body, per Cancer Council Australia’s guidance [1] and the AAD’s one-ounce reference [2]. Divide your bottle by that daily amount and you get its real lifespan, and from there the monthly cost.
The useful surprise runs both ways. If the monthly number looks high, that’s an argument for finding a well-priced daily bottle you’ll actually use generously; our off-price guide covers buying Korean sunscreen cheaply without getting burned on freshness, and the body sunscreen guide compares picks where volume matters most. And if your current bottle somehow lasts six months of daily use, the math is telling you something else: the dose is short. The how much sunscreen guide shows what a full dose looks like.
Sources
[1] Advice on sunscreen, Cancer Council Australia (about 35 ml or around 7 teaspoons for full-body coverage; at least one teaspoon per zone): link
[2] How to Apply Sunscreen, American Academy of Dermatology (about one ounce for the body; about one teaspoon for the face): link