If you’ve ever looked at professional skincare formulas, you’ve probably noticed that they are written in percentages instead of grams or ounces.
At first, this can seem confusing. Many DIY recipes online list ingredients in grams, tablespoons, or teaspoons.
However, cosmetic formulators almost always write formulas using percentages.
Using percentages makes it possible to scale formulas, adjust ingredient levels, and maintain the correct balance between ingredients.
Once you understand how percentages work, it becomes much easier to create and modify skincare formulas.
If you’re new to making skincare products, start with our guide:
Skincare Formulation for Beginners
Why Cosmetic Formulas Use Percentages
Percentages allow a formula to work at any batch size.
Instead of being tied to a specific amount of ingredients, the formula simply describes how much of each ingredient should be present relative to the total formula.
For example:
| Ingredient | Percentage |
|---|---|
| Water | 70% |
| Carrier Oil | 20% |
| Emulsifier | 5% |
| Additives | 5% |
This formula will always add up to 100%.
Because the ingredients are listed as percentages, you can easily make:
100 grams
500 grams
1 kilogram
The ratio between ingredients remains exactly the same.
Why Grams Are Still Important
While professional formulas are written in percentages, you still need to convert them into grams when making the product.
Grams are used during production because they allow for accurate measurement.
Weight-based measurement is far more precise than measuring ingredients by volume (like teaspoons or tablespoons).
This is especially important when working with ingredients such as:
preservatives
emulsifiers
active ingredients
Using too much or too little of these ingredients can affect product stability and safety.
Learn why preservatives are essential in water-based formulas here:
Why Preservatives Matter in DIY Skincare
How Percentages Work in Skincare Formulas
A percentage represents the portion of the total formula that an ingredient occupies.
For example:
If a formula contains 10% oil, it means that oil represents 10% of the total product weight.
If your batch size is 100 grams, then:
10% oil = 10 grams.
If your batch size is 500 grams, then:
10% oil = 50 grams.
The ratio remains consistent.
This flexibility is the reason percentages are used in professional formulation.
How to Convert Percentages to Grams
Converting percentages into grams is simple.
Use this formula:
Ingredient weight = total batch size × percentage
Example:
If you want to make a 200g lotion with the following formula:
| Ingredient | Percentage |
|---|---|
| Water | 70% |
| Oil | 20% |
| Emulsifier | 5% |
| Preservative | 1% |
| Other ingredients | 4% |
You calculate each ingredient like this:
Water
200 × 0.70 = 140g
Oil
200 × 0.20 = 40g
Emulsifier
200 × 0.05 = 10g
Preservative
200 × 0.01 = 2g
Other ingredients
200 × 0.04 = 8g
Now you have the full formula in grams.
Example Lotion Formula Conversion
Let’s walk through a simple lotion example.
Percentage Formula
| Ingredient | Percentage |
|---|---|
| Distilled Water | 72% |
| Carrier Oil | 15% |
| Emulsifier | 6% |
| Glycerin | 4% |
| Preservative | 1% |
| Fragrance | 2% |
Total = 100%
Now we convert this formula to grams.
100g Batch
| Ingredient | Weight |
|---|---|
| Water | 72g |
| Oil | 15g |
| Emulsifier | 6g |
| Glycerin | 4g |
| Preservative | 1g |
| Fragrance | 2g |
If we increase the batch size to 500g, we simply multiply each percentage again.
This scaling ability is one of the biggest advantages of percentage-based formulas.
Why Percentages Make Formulation Easier
Using percentages allows formulators to:
Scale formulas easily
Adjust ingredient levels
Maintain formula balance
Compare formulas quickly
For example, if you want a richer lotion, you might increase the oil phase from 15% to 20%.
If the formula were written in grams, it would be harder to see the relationship between ingredients.
Understanding Formula Structure
Most skincare formulas follow a basic structure.
Water Phase
The water phase typically contains:
distilled water
hydrosols
aloe vera juice
glycerin
These ingredients provide hydration.
Oil Phase
The oil phase contains ingredients such as:
carrier oils
plant butters
oil-soluble vitamins
Carrier oils play a major role in skincare products.
Learn more in our guide:
Carrier Oils in Skincare: How to Choose the Right Oil for Your Skin
Emulsifier
If a formula contains both oil and water, it needs an emulsifier to keep the phases mixed.
Learn more here:
Emulsifiers in Skincare: What They Are and How They Work
Cool Down Phase
The cool-down phase contains heat-sensitive ingredients.
Examples include:
preservatives
essential oils
fragrance oils
active ingredients
These ingredients are added once the formula has cooled.
Common Beginner Mistakes with Percentages
Learning to work with percentages takes practice. Beginners often make a few common mistakes.
Not Adding Up to 100%
A proper formula should always total 100%.
If the percentages add up to more than 100%, the formula needs adjustment.
Forgetting to Recalculate When Changing Ingredients
If you increase one ingredient, you must decrease another so that the total remains 100%.
Using Volume Instead of Weight
Skincare ingredients should always be measured by weight.
Volume measurements can be inconsistent and lead to inaccurate formulas.
When to Use Percentages vs Grams
| Situation | Best Method |
|---|---|
| Writing a formula | Percentages |
| Producing the product | Grams |
| Scaling batches | Percentages |
| Measuring ingredients | Grams |
Professional cosmetic formulation uses both methods together.
Percentages define the formula, while grams are used during production.
Why Percentages Are Important for Stable Products
Maintaining the correct ratios between ingredients is critical for product stability.
For example:
Too little emulsifier can cause a lotion to separate.
Learn more about this problem here:
Why Some DIY Skincare Separates and How to Fix It
Using percentages helps ensure that ingredients stay within safe and effective ranges.
Tips for Beginners Learning Percentages
If you’re new to formulation, these tips can help.
Start with 100g test batches.
This makes percentage conversion simple.
Use a digital scale that measures grams.
Keep a formulation notebook to track changes and improvements.
Over time, working with percentages becomes second nature.
FAQ
Why do cosmetic formulas use percentages?
Percentages allow formulas to be scaled to any batch size while maintaining the correct ratio between ingredients.
How do you convert percentages to grams?
Multiply the total batch size by the ingredient percentage.
Example:
200g batch × 10% = 20g ingredient.
Do DIY skincare recipes need percentages?
Using percentages is not required for simple recipes, but it becomes extremely helpful when developing or modifying formulas.
Why is weight better than volume in skincare formulation?
Weight measurements are more precise and consistent than volume measurements, which can vary depending on ingredient density.
One thought on “Percentages vs Grams in Skincare Formulation (Beginner Guide)”
Comments are closed.