How The Formula Finds Dupes

What “match %” actually means

The match score reflects how similar two products' formulas are — based on what ingredients they share, what those ingredients do, and where they appear in the formula. It does not compare concentrations, which brands rarely disclose.

Why ingredient order matters

Ingredients are listed by concentration, highest first. A product where niacinamide appears second is very different from one where it appears twentieth — even if both technically “contain” niacinamide. We weight earlier ingredients more heavily to reflect this.

Hard rules we always enforce

Some matches are never shown regardless of score:

• SPF products only match other SPF products. A sunscreen is never a dupe for a moisturizer.
• Prescription actives (tretinoin, adapalene, azelaic acid, benzoyl peroxide) only match products with the same active — no substitutions.
• Body, hair, and lip products never match face skincare.

Why some searches return few results

A high match threshold means we'd rather show you one genuinely similar product than ten loosely related ones. Some products — especially unique vitamin C formulas or prescription treatments — have few true dupes. That's an honest answer, not a gap in our database.

What we can't tell you

We don't know exact concentrations. We don't know if a formula has changed recently (though you can flag this on any product page). We don't factor in price, availability, or brand reputation — just the formula.