How to Calculate Cosmetic Formulation Amounts from Percentages

Asked by: af4646 On: May 21, 2017 Product Type: Cosmetics Answered

Question

How do I calculate the required amount of each ingredient in a cosmetic formulation based on its percentage? For example, if I want to make 50 grams of a serum with the following formula:

  • Water: 95%
  • Substance A: 3%
  • Substance B: 2%

How do I calculate the weight in grams for each ingredient?

Answer

Calculating the amount of an ingredient based on its percentage in a formulation is quite straightforward. The percentage tells you what proportion of the total weight of your final product should be that specific ingredient.

The basic formula is:

Ingredient Weight = (Ingredient Percentage / 100) * Total Formulation Weight

Let's use the example you shared to illustrate:

Suppose you want to make a serum with a total weight of 50 grams, and the formula is:

  • Water: 95%
  • Substance A: 3%
  • Substance B: 2%
    (Note: The percentages should add up to 100%)

Here's how you calculate the weight for each ingredient:

  • Water (95%):
    (95 / 100) * 50 grams = 0.95 * 50 = 47.5 grams

  • Substance A (3%):
    (3 / 100) * 50 grams = 0.03 * 50 = 1.5 grams

  • Substance B (2%):
    (2 / 100) * 50 grams = 0.02 * 50 = 1.0 gram

To check your calculation, add up the weights of all ingredients:
47.5 g (Water) + 1.5 g (Substance A) + 1.0 g (Substance B) = 50 grams

This total matches the desired total weight of your serum, so the calculations are correct.

This method applies to any ingredient in your formula. Just take its percentage, divide by 100, and multiply by the total weight of the batch you want to make.

Answer Update
Updated Review: May 2026

This section was added after reviewing the original answer against current product availability and formulation knowledge at the stated point in time.

As of May 17, 2026, while the fundamental calculation remains the same, many formulators now prefer using ready-to-use bases to simplify the process. For example, using a pre-stabilized base like Silky Serum Base or ANR Serum Base allows you to focus on adding specific active ingredients without worrying about complex emulsification math. If you are looking to replicate a specific commercial product, professional services such as "Develop the Make Up formula to be the same as the original" are also available to handle technical analysis and matching for you.

Tags

Amount Calculation Cosmetic Formulation Ingredient Ratio Serum Usage Percentage