K-Beauty ingredient percentages: ask what the number measures
Understand percentages and ppm using a simple calculation, while keeping ingredient blends and finished formulas distinct.
A percentage is useful only when you know what it measures. On a beauty page, a large number may describe an ingredient, an extract solution or a named blend. Write down the noun beside the number before comparing two products. The larger figure is not automatically the larger amount of the same substance.
A calculation with an explicit denominator
Consider an invented formula containing 10% of a premixed ingredient solution. Suppose the manufacturer explicitly states that this solution contains 2% of substance X by mass. Under those assumptions, X contributes 0.2% of the finished formula by mass: 10% multiplied by 2%. Without the second figure and the shared measurement basis, the calculation cannot be made. This is an arithmetic example, not a claim about any named cosmetic.
On the same basis, one percent equals 10,000 parts per million. Thus 5,000 ppm equals 0.5%. A conversion does not reveal whether the figure refers to a dry ingredient, a liquid extract, a mixture or the finished product. Preserve the original wording and ask the brand when the basis is missing.
What an ingredient list can tell you
For U.S. cosmetics, FDA guidance describes a generally descending ingredient order with exceptions, including ingredients at one percent or less and color additives. A position in the list therefore does not disclose an exact concentration. Do not estimate a precise percentage simply by counting how far down a name appears.
Make a comparison card
- Copy the exact ingredient or blend name and the stated number.
- Record whether the unit is percent, ppm or another measure.
- Note the basis and the source of the figure, if supplied.
- Mark unknown details as unknown instead of filling them in.
- Compare performance only using evidence for the finished product and stated use.
THE CAST recommends keeping this numerical worksheet beside the complete product label. It helps you ask a precise question without turning a concentration claim into a promise of suitability or results.