How We Rate

1. What a rating is

Every rated product in Decify gets a number out of 100. It answers one question: how good is this product, for what it is?

The rating is worked out from the product's ingredient list and nothing else. It does not use brand, price, advertising, popularity or any commercial relationship. No brand can pay for a rating, or for a change to one.

It is our own editorial assessment, produced by the same method for every product, so that two products of the same kind can be compared fairly.

2. Where the information comes from

• Ingredient lists are taken from what is printed on the pack, or published by the brand or a retailer. Where the two differ, we prefer the pack.
• Ingredient assessments (what an ingredient does, and whether it deserves care) are prepared by our team from published research, and reviewed before they are used.
• Submissions from people using the app are never treated as fact until we have checked them.

3. How a rating is built

Each rating combines two scores, each out of 100:

• Efficacy: does the formula contain what a product like this needs in order to do its job, and at a sensible level?
• Tolerability: how likely is the formula to cause trouble, based on the ingredients in it that deserve care?

The two are blended, and the blend depends on the type of product. For an exfoliant or a treatment, whether it works counts for more. For a cleanser or a moisturiser, being gentle counts for more.

The type of product matters in a second way. A cleanser does its job through cleansing agents rather than "active" ingredients, and an exfoliant needs an acid that is, by nature, more likely to irritate. So each score is measured against what is reasonable for that kind of product. That is what "for what it is" means, and it is why a rating compares products of the same kind far better than products of different kinds. A 78 moisturiser and a 78 cleanser are each good examples of their kind. They are not interchangeable.

4. What moves a rating

Ingredients that do the product's job

Products earn efficacy credit for the ingredients that give them their purpose. The strongest few count most. Adding more of the same kind of ingredient adds less each time, so a long ingredient list cannot outscore a short one on length alone.

Position on the list

By law, ingredients are listed from the highest amount to the lowest. So for ingredients that deserve care, higher up the list means more weight. Active ingredients are the exception: they are effective in small amounts, so their credit does not fall away when they sit lower down.

Amounts, where we know them

When a pack states how much of an ingredient it contains, we compare that with the range generally used for that type of product. Being within the range earns credit. Being clearly below it earns less, because it may be too little to do much. Being above it is not marked down for efficacy, because more can be the whole point of a product.

Ingredients that deserve care

Each ingredient in a product carries a coloured dot. A dot shows how much care an ingredient deserves in that product. It is not a judgement that the ingredient is unsafe. The more weight a flagged ingredient carries, and the less it contributes to the product's purpose, the more it costs tolerability. An ingredient we cannot assess costs a small amount. That reflects uncertainty, not harm.

An ingredient can be flagged and also be the reason a product exists. For example, an acid in an exfoliant. In that case its cost to tolerability is small, because its purpose is already credited under efficacy.

5. A worked example

This product is made up, and so are its numbers. It shows how the parts fit together, not a real rating.

Take out the fragrance and its tolerability would rise. Swap in a stronger cleansing agent and its efficacy would. In both cases the product would move by a few points, and only because of the ingredients in it.

6. The four bands

The rating is shown as a number and as one word:

The words describe how the formula scores on our method. They do not say a product is unsafe or that it should not be used. See section 8.

7. When there is no rating

We would rather show no rating than a wrong one. A product is left unrated when we cannot stand behind the number. That happens when its ingredient list is missing or incomplete, or when too many of its ingredients are ones we have not yet been able to assess. Unrated products still show whatever we do know about their ingredients.

8. What a rating is not

• It is not medical advice, and it does not take your skin, allergies or health into account. Analysis is general-skin only.
• It is not a safety finding, a laboratory measurement or a regulatory rating.
• It does not say that a product will or will not work for you, or that it is unlawful, unsafe or unsuitable for anyone.
• A lower rating does not mean a brand or a product is bad. It means the formula scores lower on this particular method.

If you have a skin condition or a known allergy, check the full ingredient list against advice from a doctor or pharmacist.

9. Known limits

• Formulas change, and the same product can differ between countries. If the pack in your hand differs from what we show, trust the pack, and let us know.
• Our assessments can be wrong or out of date. We keep them under review and fix them when we find a mistake.
• Ingredient amounts are often not published. Where they are not, the position on the list stands in for them.
• Ratings compare products of the same kind much better than products of different kinds.
• Method changes over time as we learn. When they do, ratings are recalculated and this page is updated with a new version.

10. Ask us for a correction

Anyone can ask us to correct a product, including the people who make it. We review every request.

Email support@decifyapp.com with the subject line Correction request, and include:

• the product name and, if you can, its barcode;
• what you believe is wrong (the ingredient list, an ingredient's assessment, the product's category, or something else);
• the evidence: a photograph of the pack, the brand's official ingredient list, or a published source.

What happens next:

• We check what you send against the pack and the sources.
• If we find a factual mistake, such as a wrong or outdated ingredient list, we correct it, and the rating updates with it.
• If the disagreement is about our judgement of an ingredient, we will look at it again and tell you what we decided and why. We may change the assessment for every product it affects, not just yours.
• Whatever we decide, we will tell you.

Two things we will not do. We will not change a rating because of who asks, or in return for payment, sponsorship or advertising. And we will not change a rating without a reason that applies equally to every other product. The method is the same for everyone.

Change log