Calculating Ingredient Percentages by Weight for Cosmetic Formulas
Question
How to calculate ingredient quantities for a cosmetic formula based on percentages, such as 30% total ingredients and 70% water, to make a specific amount like 100 grams or 50 grams of cream? Should the calculation be based on volume (ml) or weight (grams)?
Answer
Thank you for your question.
Your understanding of calculating ingredient quantities based on percentages is close, but there's an important point to consider.
Generally, the proportions of ingredients in cosmetic formulations are calculated by weight (grams), not volume (ml). This is because each ingredient has a different density, and using volume can lead to inaccurate actual weight proportions.
Therefore, if a formula specifies 30% total ingredients and 70% water, and you want to make 100 grams (not 100 ml) of cream, the correct calculation would be as follows:
- Total Ingredients: 30% of 100 grams = 30 grams
- Water: 70% of 100 grams = 70 grams
- Total: 30 grams + 70 grams = 100 grams (total weight of the cream)
If you want to make 50 grams of cream, the calculation would be:
- Total Ingredients: 30% of 50 grams = 15 grams
- Water: 70% of 50 grams = 35 grams
- Total: 15 grams + 35 grams = 50 grams (total weight of the cream)
In summary: Your percentage calculation method is correct, but the unit used for calculation and weighing ingredients should be weight (grams) to ensure accurate proportions according to the formula.
I hope this explanation is helpful! Please feel free to ask if you have any further questions.