The Data — Skincare
SPF: What the Number Actually Measures
SPF is a tested figure under a published protocol, and it measures one thing — sunburn, caused by UVB. The rays that age skin are covered by a separate designation most buyers never read.
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SPF stands for sun protection factor and it is measured, not claimed. A panel of volunteers is exposed to a solar simulator with and without the product, and the factor is the ratio between the doses that produce visible redness.
This page reads the FDA test method against owner reports on 6 sunscreens, ranked by rating and then by number of ratings on the method in how we choose. No product was applied or tested.
EltaMD UV Daily Broad-Spectrum SPF 40
Good fit You want a daily face sunscreen rather than a beach one
Not for You need water resistance for swimming
Neutrogena Clear Face Broad-Spectrum SPF 50
Good fit Sunscreen has caused breakouts before
Not for You want a mineral filter
EltaMD UV Clear Broad-Spectrum SPF 46
Good fit You want the deepest owner record here
Not for You are covering a body, not a face
Neutrogena Ultra Sheer Dry-Touch SPF 70
Good fit You want a body sunscreen that does not feel greasy
Not for You are paying for the number expecting proportional protection
CeraVe Hydrating Mineral Sunscreen Sheer SPF 30
Good fit You want mineral filters without a heavy finish
Not for You spend hours outdoors at midday
Blue Lizard Sensitive Mineral Sunscreen SPF 50
Good fit Chemical filters sting or irritate
Not for A visible cast would stop you wearing it
The number is a UVB number
Redness is sunburn and sunburn is caused by UVB. So the entire SPF scale measures protection against 1 band of ultraviolet light, and it says nothing about the other one.
UVA penetrates deeper, does not burn, and drives photoageing and pigmentation. A product can post a high SPF while filtering UVA poorly, which is precisely why a second designation exists.
Broad-spectrum is that designation. In the United States it requires passing a critical-wavelength test, which checks that the product absorbs across the UVA range rather than only the burning band. A sunscreen without those two words is a sunburn product.
| Label | What it certifies |
|---|---|
| SPF number | UVB protection, measured on skin |
| Broad-spectrum | UVA coverage across the range |
| PA+ to PA++++ | UVA grade used in Asia, 4 tiers |
| Water resistant 40 or 80 min | Tested through immersion for that time |
EltaMD UV Clear Broad-Spectrum SPF 46
70,691 ratings makes this the most-reviewed sunscreen here, and the reports are about texture rather than protection.
Current price shown on Amazon. We may earn a commission.
| SPF | 46, broad-spectrum |
|---|---|
| Evidence | 70,691 ratings |
| Owners praise | Light on sensitive skin |
70,691 ratings makes this the most-reviewed sunscreen here, and the reports concentrate on how it wears rather than on whether it works. Owners describe it as light enough for sensitive skin and unobtrusive under makeup.
That focus is the useful signal. Once a product is broad-spectrum at 30 or above, the remaining variable is whether you will actually put it on every morning, and texture decides that.
Buy it if
- You want the deepest owner record here
- Sensitive or reactive skin
Don't buy it if
- You are covering a body, not a face
Where the scale flattens
SPF 15 blocks about 93% of UVB. SPF 30 blocks about 97%. SPF 50 blocks about 98%.
Doubling from 30 to 60 does not double anything. It moves roughly 1 percentage point of transmitted UVB, which is why regulators in several markets cap the printed number at 50+ rather than letting it climb.
The band worth buying is 30 to 50. Below 30 the margin for imperfect application disappears; above 50 you are paying for a number rather than a difference you can measure.
Neutrogena Ultra Sheer Dry-Touch SPF 70
SPF 70 against SPF 30 is a difference of roughly one percentage point of UVB blocked, and 40,124 ratings say the texture is why people buy it.
Current price shown on Amazon. We may earn a commission.
| SPF | 70, broad-spectrum |
|---|---|
| Filters | Chemical |
| Owners praise | Dry finish |
SPF 70 sits above the point where the curve flattens, and against SPF 30 the difference is about a percentage point of UVB. That is the arithmetic, stated plainly.
It is still a sensible purchase, for a reason the number does not capture: 40,124 ratings praise the dry, non-greasy finish, and a sunscreen people reapply generously outperforms a higher-SPF one they use sparingly.
Buy it if
- You want a body sunscreen that does not feel greasy
- A high number reassures you into applying it
Don't buy it if
- You are paying for the number expecting proportional protection
The test assumes more product than anyone uses
The protocol applies 2 milligrams per square centimetre of skin. For a face and neck that works out to roughly a third of a teaspoon, and for a whole body in swimwear it is around 30 millilitres — a shot glass.
Most people apply between a quarter and a half of that. Protection does not fall linearly with the shortfall, so a thin layer of SPF 50 can deliver something closer to the teens in practice.
Applying more of an SPF 30 beats applying a smear of an SPF 70, and reapplying every 2 hours outdoors matters more than either.
CeraVe Hydrating Mineral Sunscreen Sheer SPF 30
SPF 30 is the floor the American Academy of Dermatology recommends, and this is the sheer mineral version of it.
Current price shown on Amazon. We may earn a commission.
| SPF | 30, broad-spectrum |
|---|---|
| Filters | Mineral, sheer |
| Watch | Newer listing, fewer reviews |
SPF 30 is the floor the American Academy of Dermatology recommends, and this is the sheer mineral version of that floor with a hydrating base.
4.5 across 3,859 ratings, a newer listing with fewer reviews yet. For daily indoor-and-commute exposure it is enough; for a day at the beach, buy higher and reapply.
Buy it if
- You want mineral filters without a heavy finish
- Dry skin that needs the base to hydrate
Don't buy it if
- You spend hours outdoors at midday
Mineral filters against chemical filters, and the white cast
Mineral filters are zinc oxide and titanium dioxide. They sit on the surface, work immediately on application, and are the usual recommendation for reactive skin. Their historic problem is a white cast, which is worse on deeper skin tones and is the reason people abandon them.
Chemical filters absorb ultraviolet and convert it to heat. They are cosmetically elegant, disappear on every skin tone, and are the ones most likely to sting around the eyes.
Neither is more effective as a class, and the FDA monograph treats both as acceptable filters. The choice is about which one you will wear, and reactive skin decides it faster than any other factor. Of the 6 products here, 2 are mineral.
Blue Lizard Sensitive Mineral Sunscreen SPF 50
A mineral formula at SPF 50 across 21,598 ratings, for skin that reacts to chemical filters.
Current price shown on Amazon. We may earn a commission.
| SPF | 50, broad-spectrum |
|---|---|
| Filters | Mineral |
| Watch | White cast on deeper skin tones |
A mineral SPF 50 at 4.4 across 21,598 ratings, in a filter type many people only reach for after a reaction to a chemical one.
The cast is the thing to check in daylight rather than in a bathroom mirror. Mineral formulations have improved substantially, and they still show more on deeper skin tones than a chemical filter does.
Buy it if
- Chemical filters sting or irritate
- You want the filter sitting on the surface
Don't buy it if
- A visible cast would stop you wearing it
Neutrogena Clear Face Broad-Spectrum SPF 50
4.6 on an oil-free formula built for skin that breaks out, which removes the most common reason people skip sunscreen entirely.
Current price shown on Amazon. We may earn a commission.
| SPF | 50, broad-spectrum |
|---|---|
| Formula | Oil-free |
| Rank here | Joint highest rated |
4.6 puts this joint top of the page on rating, on an oil-free formula aimed at skin that breaks out. That matters more than it sounds — sunscreen causing spots is a common reason people stop wearing it.
SPF 50 in a light texture is the right end of the band. If a previous sunscreen ended up in a drawer because of how it felt, this is the category of formula that solves it.
Buy it if
- Sunscreen has caused breakouts before
- You want a high number in a light texture
Don't buy it if
- You want a mineral filter
Daily use is a different purchase from beach use
EltaMD UV Daily Broad-Spectrum SPF 40
4.6 across 44,856 ratings, and SPF 40 rather than a headline number — which is the point of the arithmetic below.
Current price shown on Amazon. We may earn a commission.
| SPF | 40, broad-spectrum |
|---|---|
| Owners praise | Wears under makeup |
| Rank here | Joint highest rated |
4.6 across 44,856 ratings, at SPF 40 rather than a headline figure, and owners specifically report it sitting well under makeup. That is a daily-wear product rather than an outdoor one.
Read the absence of a big number as a design decision. A facial sunscreen is competing on texture and finish, because those decide whether it gets used 300 days a year.
Buy it if
- You want a daily face sunscreen rather than a beach one
- You wear makeup over it
Don't buy it if
- You need water resistance for swimming
What to check on the bottle
Confirm broad-spectrum, confirm SPF 30 or higher, and then stop reading numbers and start reading texture. Check the water-resistance minutes if you swim, because that claim is tested and time-limited rather than absolute.
Then apply a third of a teaspoon to the face and reapply outdoors. Sun protection is also the non-negotiable half of any retinoid routine, which what the retinoid percentage means works through. The products that do it well are in the sunscreen shortlist, and two formulations at the same SPF are set against each other in EltaMD UV Clear against UV Daily. The same gap between a printed figure and a real-world one shows up in what the earbud spec sheet hides.
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