How we rate · 🌊 Water resistance
How we rate water resistance, reading sweat and swim staying power off the ingredient list
Water resistance is not the SPF number, and it is not a bottle you have to trust on faith. It comes from the formula: a handful of film-forming polymers and waxes that lock the UV filters onto your skin so sweat and water do not rinse them off in minutes. RateMySPF reads those ingredients on every sunscreen in our catalog and scores how well each one is built to stay put, so below we walk through exactly what drives a water-resistance score and point to real products that show each lever. One thing up front: this is a capability, higher means more resistant, but a low score is not a flaw. A daily face SPF that washes off easily is perfectly fine for the office, which is why water resistance sits outside the overall score.
TL;DR: the ingredients that drive water resistance
- VP/Eicosene Copolymer: a classic water-resistant film former; the resin sport and beach sunscreens lean on to survive water
- Acrylates Copolymer: long-wear acrylic film former, the most common water-resistance polymer across the catalog
- Acrylates/Octylacrylamide Copolymer: transfer- and water-resistant film former that makes filters cling through sweat
- Polyurethane-34: flexible film-forming polymer that builds a water-resistant layer without a heavy feel
- Carnauba Wax: a hard plant wax that water-locks stick and balm formulas; the backbone of waterproof sun sticks
- Synthetic and microcrystalline wax: structural waxes that resist water in sticks and rich creams, a secondary resistance signal
- Sport or 80-minute claim: a label hint we credit lightly: the regulated 40 or 80 minute figure needs a wash test we cannot read from INCI
What "water resistance" actually means here
When a sunscreen claims to be water-resistant, it is promising that its UV filters stay on your skin while you sweat or swim, instead of sliding off with the first splash. That staying power comes almost entirely from two ingredient families: film-forming polymers (the acrylates, VP copolymers and polyurethanes) and structural waxes. They form a thin, flexible layer that holds the filters in place. No film formers and no waxes means nothing is anchoring the sunscreen, so it rinses away quickly.
So this is a capability rating, not a risk and not a quality grade: higher means it holds on longer in water, and the low end is simply neutral. We read the film formers and waxes in the list, weight each by how high up it sits (presence near the top counts for more), cap each group so one family cannot run away with the score, and add a small bonus when the name itself claims sport or water resistance. The three levels that fall out are not resistant, resistant and very resistant.
Because a non-resistant sunscreen is exactly right for everyday indoor wear, water resistance is kept out of the overall score, the same way we treat finish or moisture. It is a use-case filter for sport, the beach and the pool, not a mark against a gentle daily fluid. And one honest caveat: we estimate whether a formula is built to resist water, we cannot read the exact regulated 40 or 80 minute figure off an ingredient list, because that number comes from a standardised wash test.
▼ Film formers: the polymers that actually lock sunscreen on
Lowers risk
The single biggest driver of a water-resistance score is the film former. These are the long-wear resins, VP/Eicosene Copolymer, Acrylates Copolymer, Acrylates/Octylacrylamide Copolymer, the polyurethanes and their relatives, that dry down into a continuous, water-repelling layer over the filters. We credit the group up to a cap, weighting each polymer by position, because a film former in the first few ingredients is doing structural work, while one near the tail is a minor finishing touch.
This is why a plain-looking lotion can be genuinely water-resistant without any sport branding at all. Sun Bum's SPF 50 Lotion and Equate Ultra Light SPF 50 both build their resistance on acrylates film formers carried high in the list, landing them firmly in the very-resistant tier on chemistry alone. The filters are not better than a daily cream's; they are just anchored better.
It also means "water-resistant" and "feels heavy" are different questions. Modern film formers can be remarkably light. Neutrogena's Ultra Sheer Face Mist scores very resistant off its film-forming base while still wearing like a quick mist: the polymer does the gripping, not a thick occlusive layer.
Water resistance built on film formers alone, no sport label required:
▼ Waxes and resins: the water-locking backbone of sticks
Lowers risk
The second signal is structural wax. Carnauba and beeswax, microcrystalline, synthetic and polyethylene waxes, plus silicone resins, give a formula a water-repelling skeleton. They matter most in sun sticks and balms, where the whole product is essentially wax holding pigment and filters together, so it shrugs off water by design. We score the wax group on its own capped track, lighter than film formers but enough to lift a wax-heavy stick into the resistant tiers.
Korean waterproof sun sticks are the clearest case. Scinic's Enjoy Waterproof Airy Sun Stick and Tocobo's Vita Waterproof Sun Stick reach the resistant range almost entirely on their wax backbone, which is exactly why a stick survives a sweaty hike better than the same brand's watery fluid.
Waxes and film formers also stack. A formula that carries both, a sport lotion with acrylates plus a wax network, builds resistance from two directions and tends to land at the top of the scale rather than the middle.
Wax-backed sticks that resist water without a film-former base:
● The sport and "80 minute" claim: a hint we weight lightly
Neutral
When a product name says water resistant, waterproof, sweat proof, sport, or a 40 or 80 minute figure, we add a small flat bonus. It is a real signal: a brand that tests and prints an 80-minute claim usually did formulate for it. But it is deliberately a nudge, not the main event. The word is easy to print; the polymers are what actually hold the sunscreen on.
That is why the claim is a corroboration, never a substitute. Coppertone Sport, Equate Sport Spray and Coola Classic Face Sport all earn the claim bonus, but they reach the very-resistant tier because they also carry the film formers to back it up. Take the chemistry away and the claim alone would barely move the score.
The flip side: we cannot verify the exact 40 versus 80 minute rating from an ingredient list, because that number comes from a regulated in-water test, not the INCI. So our score answers "is this built to resist water, and roughly how much", not "this is certified for 80 minutes". For the US OTC subset, pulling the official drug-facts figure from openFDA is a planned upgrade.
Sport-claimed formulas that also carry the chemistry to earn it:
● Position matters: a film former at the bottom is near-trace
Neutral
As with our other axes, where an ingredient sits changes how much it counts. A film former or wax in the first several ingredients is structural and gets close to full weight; the same polymer near the bottom of the list is often a minor texturiser and is tapered down. A single film former buried deep is not enough to make a sunscreen water-resistant, and our score reflects that.
This separates a genuine sport formula from one that sprinkles a trace of acrylates for slip. Neutrogena's Ultra Sheer Dry-Touch SPF 100, a true water-resistant lotion, stacks its film formers high and lands at the very top of the scale. A daily moisturiser with one copolymer at position 30 stays not resistant, because that trace is doing nothing to hold the filters through a swim.
We are deliberately conservative here: a formula has to genuinely build a water-resistant layer to score for it, rather than borrow the look of one from a famous ingredient listed near the end.
Film formers stacked high for real, top-of-scale water resistance:
● Why "not resistant" is not a bad score
Neutral
Most sunscreens in the catalog are not resistant, and the great majority of those are exactly what they should be: light daily fluids and tone-up creams meant for indoor wear and a commute. Ombra Daily Defence SPF 50 and innisfree's Daily UV Tone-Up sit at the bottom of this scale, and that is the right result. You do not want a heavy water-locking film on your face for a day at a desk.
Because the low end is genuinely neutral, water resistance is kept out of the overall score. A gentle daily SPF is never penalised for washing off easily; it is simply not the tool for a triathlon. Treat this axis as a filter you switch on when the use case calls for it, sport, swimming, heavy sweat or long hours outdoors, and ignore it the rest of the time.
When you do need it, pair Water resistant with High protection to find the formulas that both cover the full spectrum and stay on while you are in the water.
Daily-wear sunscreens that score not resistant, and should:
How to read a sunscreen's real water resistance
Skip the front of the bottle and scan the ingredient list for the polymers. A copolymer in the name, VP/Eicosene, Acrylates, Acrylates/Octylacrylamide, a Polyurethane, or a wax (carnauba, beeswax, synthetic, microcrystalline) carried in the first half of the list is what tells you the formula is built to stay on. A clean list of just filters, water, alcohol and humectants, with no film former in sight, will rinse off fast no matter what the label says.
Then read the claim as a question, not an answer. Water resistant (80 minutes) or sport is a good sign only when the polymers are there to back it up. And remember the rule that holds for every sunscreen: water resistance buys time, it does not make protection permanent. Reapply after toweling off, after a long swim, and at least every two hours in the sun, even with a very-resistant formula.
We rate every sunscreen in our catalog for water resistance.
Browse water-resistant sunscreensFrequently asked questions
What makes a sunscreen water-resistant?
The formula, not the SPF number. Film-forming polymers (acrylates, VP copolymers, polyurethanes) and structural waxes dry into a thin layer that holds the UV filters on your skin, so sweat and water do not rinse them off as quickly. A sunscreen with no film formers or waxes washes off fast regardless of its SPF.
Does water-resistant mean waterproof?
No. No sunscreen is fully waterproof, which is why that word is not allowed on US labels. Water-resistant means it keeps working for a set time in water, usually 40 or 80 minutes, after which it has thinned enough that you need to reapply.
How is this different from the UV protection score?
Protection grades how completely the filters cover the UV spectrum; water resistance grades how well the formula stays on long enough for those filters to keep working in water. A sunscreen can have excellent filters but wash off in minutes, or hold on beautifully with a merely decent filter set. The two are scored separately.
Why is water resistance not part of the overall score?
Because a low score is not a flaw. A daily face sunscreen that is not water-resistant is exactly right for indoor wear and a commute, so penalising it would be wrong. Water resistance is a capability you filter for when the use case calls for it, like finish or moisture, so it sits outside the overall rating.
Do I still need to reapply a water-resistant sunscreen?
Yes. Water resistance buys time, it does not make protection permanent. Reapply after swimming or heavy sweating, after toweling off, and at least every two hours of sun exposure, even with a very-resistant formula.
Which ingredients make a sunscreen water-resistant?
Mainly film-forming polymers: VP/Eicosene Copolymer, Acrylates Copolymer, Acrylates/Octylacrylamide Copolymer and the polyurethanes. Structural waxes (carnauba, beeswax, microcrystalline, synthetic) add resistance too, especially in sun sticks and balms. The higher up the list they sit, the more they count.
My sunscreen says 'water resistant 80 minutes' but scored only resistant. Why?
The claim is a hint we weight lightly; the real driver is the film formers and waxes in the formula. If a product prints the claim but carries only a little film former, or carries it low in the list, it lands in the middle of the scale. We cannot read the exact 40 or 80 minute figure from an ingredient list, because that comes from a standardised wash test.
Are mineral sun sticks water-resistant?
Often yes, because of their wax base. A sun stick is mostly wax holding the minerals together, and that wax backbone resists water, which is why a stick usually survives sweat better than the same brand's watery fluid. Our score reads those waxes and lifts wax-heavy sticks into the resistant tiers.
Is a water-resistant sunscreen good for everyday face use?
It can be, but it is not required. The film formers and waxes that make a sunscreen last can feel heavier and are harder to remove, so for daily indoor wear a lighter, non-resistant formula is often more comfortable. Save the water-resistant ones for sport, the beach and the pool.
Can you tell the exact 40 vs 80 minute rating from the ingredients?
No. That figure comes from a regulated in-water SPF test, not the ingredient list, so we do not invent it. Our score estimates whether a formula is built to resist water and roughly how strongly, from its film formers, waxes and any label claim. Reading the official drug-facts minutes from openFDA for US products is a planned upgrade.