How the Dupe Finder Works
Our dupe rankings come from comparing real published ingredient lists, not brand claims or price. Here is exactly how we score a match, and what a match does and does not mean.
1. The data
We work from full INCI ingredient lists (the standardised list on every product's packaging). Our database currently holds 2748 products, of which 2127 are classified into a product type we can compare.
2. Weighted ingredient overlap
INCI lists are ordered by concentration (highest first, until the 1% line). We give earlier ingredients more weight, then measure how much two products' weighted ingredient sets overlap. Two creams that share water, glycerin and the same emollients near the top score far higher than two that only share a preservative at the very end.
3. Shared key actives
Ingredient overlap alone is not enough, so we separately check a curated list of the actives that actually define a product: niacinamide, vitamin C, retinoids, peptides, ceramides, AHAs and BHAs, ferments, UV filters and more. A dupe needs to deliver the actives that make the original worth buying.
4. The blended score
The match percentage is 60% weighted ingredient overlap and 40% shared-actives coverage. We then only ever compare like with like: a serum is only matched against serums and essences, an SPF only against other SPFs, and so on.
5. Price tiers
The £, ££ and £££ labels are an indicative price tier based on where each brand sits in the UK market, not a live price. They exist so a "dupe" is always a cheaper alternative to a pricier original. Always check the current price before buying.
6. What a match does and does not mean
A high match means the formulas are genuinely similar on paper. It does not mean the products are identical. Exact concentrations are rarely disclosed, and pH, fragrance, preservative system and texture all affect how a product performs and feels. Where two products share actives but clearly differ in richness, we flag it as a texture note. Always patch test.
7. Why some pages are not indexed
Where the best available match is weak or there are too few credible alternatives, we keep the page out of search results rather than publish a low-confidence comparison. We would rather show fewer, stronger dupes than overstate a match.