What we score, and what we refuse to score
SPF Guide scores formulation categories. A formulation category is a type of sunscreen defined by its filter system and its physical format, for example a high load zinc oxide cream, a photostable organic filter fluid, a tinted mineral base or an alcohol driven aerosol spray.
We do not score, rank, recommend or name individual products, brands, ranges or retailers. This is a deliberate structural choice rather than a limitation we are working to remove. A guide that names products has to keep buying them, keep retesting them as formulations quietly change, and keep resisting the commercial pressure that follows any published ranking. A guide that scores categories can tell you something durable: which kinds of formulation deliver protection reliably, and which kinds fail, and why.
Every score on this site therefore rates a category against published testing standards and public evidence. No score has ever been applied to a named product. No company can buy, influence or preview a score. We take no affiliate commission on sunscreen sales.
The five criteria
Every category is scored out of 100, built from five weighted criteria. The weights are fixed across the site, with one exception noted below.
| Criterion | Weight | What it measures |
|---|---|---|
| Broad spectrum evidence | 25 | Whether the filter system covers UVB and long UVA, and whether that coverage is demonstrated by the UVA in a circle mark or an equivalent rating rather than asserted |
| Realistic dose delivery | 25 | How much product actually reaches skin in normal use, compared with the two milligrams per square centimetre used in SPF testing |
| Wear and reapplication | 20 | Whether the film survives sweat, water, friction and time, and whether the format encourages reapplication or discourages it |
| Tolerability | 15 | Recorded rates of irritant, allergic and photoallergic reaction associated with the filter class and typical supporting ingredients |
| Label transparency | 15 | Whether the format usually carries the information a buyer needs: filter names, UVA rating, water resistance claim and period after opening |
The exception is that in two reviews we shift ten points of weight. In the sensitive skin review, tolerability is weighted upward because it is the reason the reader is there. In the deep skin tone review, cosmetic acceptability is folded into dose delivery, because a formulation that leaves a visible cast will not be worn and therefore delivers nothing. Where a weighting is altered, we say so on the page.
What the score bands mean
- 85 to 100. A category we would choose ourselves for the job in question. Protection, delivery and wear all hold up.
- 70 to 84. Sound with a known trade off. Usually cosmetic acceptability, durability or cost.
- 55 to 69. Works, but a better option exists for the same job at a similar price.
- 40 to 54. Structural weakness. Usually the delivered dose is far below the tested dose.
- Below 40. Should not be relied on as a primary sunscreen.
Why dose delivery is weighted as heavily as protection
SPF is measured at two milligrams of product per square centimetre of skin. Published measurements of ordinary use land consistently below that, often between a quarter and a half of the test dose, and the relationship between film thickness and protection is not linear. Halving the dose costs more than half the protection.
This means a category's laboratory performance and its real world performance can diverge sharply. A brush on powder contains perfectly good filters and delivers a small fraction of a protective film. An aerosol spray loses part of its plume to the air before it lands. A stiff mineral cream is rationed because it drags. In each case the chemistry is fine and the outcome is not, so our framework scores the outcome. The full arithmetic is set out in our application guide.
What evidence we use
Our scores draw on published international testing standards for SPF, UVA and water resistance; the permitted UV filter list that applies in the UK, including its concentration limits; published safety opinions from European scientific committees; peer reviewed literature on filter photostability, contact and photocontact allergy, and visible light effects on pigmentation; and public guidance from the NHS, the British Association of Dermatologists, Cancer Research UK, the British Skin Foundation and the World Health Organization.
We do not run our own laboratory testing, and we say so plainly rather than implying otherwise. Independent SPF testing costs several thousand pounds per product and would only produce a result about the specific batch of a specific product, which is precisely the kind of claim this site is built to avoid making.
Money, and the absence of it
No brand pays for placement here, because there is no placement to pay for. We do not name products, so there is nothing to buy. We take no affiliate commission on sunscreen sales, accept no sponsored content, and do not run advertising from sunscreen manufacturers.
The site is funded by its publisher, Northbank Media. If that ever changes, the change will be described on this page before it takes effect, not after.
Corrections
Standards change, filter permissions are revised and evidence moves. If you find something on this site that is out of date or wrong, tell us through the contact page and we will correct it and note the date of the change. Reviews carry a last reviewed date in the footer, and a page that has not been checked recently should be treated accordingly.
This is not medical advice
SPF Guide is a consumer buyer's guide. It is not a clinical service and nothing on it is medical advice. If you have a skin condition, a reaction to a product, or a mole that is changing in size, shape or colour, speak to a pharmacist or a GP rather than a website. UK guidance for the public is published by the NHS and the British Skin Foundation.