Tools / Cosmetic formula calculator
Cosmetic formula calculator: percentages to grams
Enter the finished-formula percentages and the batch size you will actually weigh. The calculator multiplies each line by batch mass and shows how much of the 100% budget is still free — by phase and in total.
This is scaling arithmetic: grams = % ÷ 100 × batch size. It does not choose ingredients or approve a formula.
Grams—
Grams—
Grams—
Add percentages and a batch size to see grams.
- Total %
- 0
- Remaining %
- 100
- Remaining g
- 100
Use the supplier TDS/COA for the real raw-material concentration, water content, and process limits. A line that says “2% active” on paper may be 2% of a 10% solution.
How the calculation works
Each ingredient line is treated as a mass fraction of the finished batch. If a serum line is 3.00% and the batch is 250 g, that line is 7.50 g. Phase totals are the same fractions grouped by the phase label you type. Remaining percent is 100 minus the sum of the lines you entered. Remaining grams uses that leftover fraction on the same batch size.
Worked example
A 100 g leave-on gel with water 88.00%, glycerin 5.00%, polymer 0.40%, preservative 1.00%, and a water-phase active 2.00% leaves 3.60% unassigned. On a 250 g batch those lines become 220.00 g, 12.50 g, 1.00 g, 2.50 g and 5.00 g, with 9.00 g still free. The leftover is not a recommended filler — it is simply the mass not yet allocated.
Common mistakes
The usual error is treating a supplier solution as 100% active, then scaling as if the bottle were the molecule. Another is letting the sheet run to 102% because “a little extra water will be fine” — the weigh-up will not match the written formula. A third is mixing weight percent with volume percent on viscous or oily lines. Weigh, do not assume 1 g = 1 mL unless the material is specified that way.
When the datasheet still wins
If the TDS gives a use range, a maximum temperature, or a dilution already built into the trade name, that document controls the bench decision. This page will happily scale a number you should not have used. Challenge tests, stability, and compatibility sit outside the arithmetic.