How to write cosmetic formulas?

May 3, 2023 | The basics

Writing and understanding cosmetic formulas is an essential skill that is quite easy to learn. After getting some knowledge on how to read and write these formulas, you will be a more confident formulator. Also, you will be able to distinguish if the found cosmetic formulas are good to try or not.


1. Simplified cosmetic formulas

Every cosmetic formula has its structure which is more or less the same. It can be a very basic with just a few things or it can be a little more complicated, but definitely worth the additional work. The simplified cosmetic formulas consist of name of ingredients, phases and percentages. While the more advanced cosmetic formulas includes everything from simplified version plus INCI name, manufacturer, function of the ingredient. 


Depending on the ingredient you may write the common name, trade name or other. If it is a butter or an oil or other very known ingredient I tend to write the common name. 

However, for preservatives, emulsifiers and some other ingredients I tend to use the trade name or the name given by the supplier. As these can vary I also try to add a link to the ingredient where I have bought it, so everyone can look at the INCI as well.


We start by looking at the whole structure of the formula. Good cosmetic formulas are always divided in several phases (if needed). You cannot just randomly write ingredients that you want, you have to assign them to the phases and write these ingredients next to each other.

The number of the phases depends on the product that you want to create. For a simple hair oil or mist you will need one phase, but for a bit more complicated cosmetic formulas such as lotions, gels, scrubs you will need more phases. Typically we will need 3 phases for a lotion – water phase, oil phase and cool down phase. But there could be more phases if needed.

To each phase we assign a letter – A, B, C, D, E, F etc. As many as we need. Then to each phase we assign the ingredients we want to use. 

Here you can see how I present my formula in three different phases. This is for the formulation for “Hair serum with caffeine”.

Phase A

80.8 g | 80.8 % Water

2 g | 2 % Caffeine

3 g | 3 % Trimethylglycine

3 g | 3 % Vitamin B3

Phase B

4 g | 4 % Vegetable silicone

1 g | 1 % Chamomile extract

1 g | 1 % Cucumber extract

1 g | 1 % Horsetail extract

1 g | 1 % Centella asiatica extract

1 g | 1 % Biogard 221 / Cosgard

Phase C

2 g | 2 % Pentylene glycol

0.1 g | 0.1 % Xanthan gum

This makes 100 g of the product.

Hair-serum-with-caffeine-and horsetail-extract-diy

Want to take better care of your hair?

Join an Oily Hair Mask Challenge and learn how to make natural oils suited for your hair!

1.2.1. How to know which ingredient goes to which phase?

This depends on ingredient solubility, heat and shear stability. Water soluble ingredients such as glycerin, sodium lactate, hyaluronic acid, niacinamide, urea and other ingredients are water soluble ingredients. They will dissolve in water, but they cannot dissolve in oil.

On the other note oils, emulsifiers, ceramides, coenzyme Q10, essential oil, fragrance oils and other ingredients are soluble in oil and will not dissolve in water. The only exception is emulsifiers which have oil and water loving parts in their structure. And depending on the technique, emulsifiers can sometimes be used in a water phase as well.

1.2.2. How to know the solubility of an ingredient?

When we formulate with ingredients we have to do at least a basic research about them in order to prepare ourselves and get to know them. In this way it will be much easier to formulate with them and we will save a lot of ingredients and money by not throwing all our creations to the trash bin.

If you want to know how to research ingredients, here is a post about it:

The main things about each ingredient should be provided by the supplier. It can be written in suppliers’ page or the supplier can provide additional data sheets were this information is written. Solubility should be mentioned here as well.

So, when we have already assigned ingredients to the phases, we should look again and see it there are any heat or sheer sensitive ingredients. These are usually the ones that can be degraded or altered when we use them in higher temperatures.

The most common heat sensitive ingredients are: preservatives, hyaluronic acid, essential and fragrance oils, heat sensitive carrier oils, vitamin E, coenzyme Q10. These ingredients will go to the cool down phase (depending on the product you are making).

Information about heat sensitivity should also be given by your supplier. However, if it is not written, you should look at different suppliers that have the same ingredients. You can also check google scholar or ingredient research database (this one needs a company e-mail address to sign up).


1.2.3. Does the order of the phases matter?

When I make a lotion I usually write all my water phase ingredients to phase A and all oil phase ingredients to phase B. I have seen many doing the other way around (water phase B, oil phase A) and I don’t think there is much difference between these two.

But you can write what is more convenient to you. The main rule is that water soluble ingredients should go to one phase and oil soluble ingredients will make up the oil phase.

You can write your ingredients in the phase as you like. But it would be much easier to write them in order of addition. For example, if an ingredient needs to be dissolved prior to other ingredients, then it should be written higher.

In this way you will see this ingredient sooner and will know that it needs to be dissolved first. This is just for convenience, but there isn’t a rule that it only can be written like this.

1.3. Percentages

To make a cohesive and easy to read formulas we write them in percentages. All added ingredients in the formula should add to 100%. Even when the formula calls for 0.1% of an ingredient, we still have to include it and write it in a formula.

Some ingredients have very low usage rates and still are very potent. So, in order to be consistent, we need to include all ingredients. Unless these ingredients are used in very very very small amounts that even our scales doesn’t pick the numbers (we use at least 0.01g increment scales). These can include micas, iron oxides etc.

In the formula we assign percentage to each ingredient. Think of the product that it has 100 parts. And when we finally make it we can tell that this product has 50 parts of one ingredient, 25 parts of other ingredient and so on until the sum of all ingredients are up to 100. Or you can imagine a pie that is divided in different ratios. It is the same thing just shown a bit differently.

For example:

50 parts of castor oil

25 parts of hemp seed oil

24.5 parts of rice bran oil

0.5 parts of vitamin E

The word parts is just a way of expressing %. So now we will right this properly with percentages.

50% castor oil

25% hemp seed oil

24.5% rice bran oil

0.5% vitamin E

We use percentages in our formulas because it gives more clarity, structure and ease. When all formulators use the same principle it will be much easier to understand a formula and may see some areas that can be improved.

It is hard to tell if a cosmetic formula is good when the measurements are different g, ml and %. Good cosmetic formulas will only have percentages and then on the side of that grams or ounces for the specific batch size.

If you ever find a cosmetic formula that uses different measurement types such as ml, g and ounces in one formula – please just don’t use it. It is not worth your time, your ingredients and patience. Just find a better starting formula.

Another reason why we use percentages is that all of the ingredients have specific usage rates and they are written in percentages. This way it is far easier to add them into a formula which uses percentages.


To make consistent products we need systematic measurements and this is why we always use weight not volume. Please forget ml, cups, spoons, drops and other inaccurate measurements. Also, we weight ingredients depending on the batch size and we never pour ingredients from a feeling that this is enough.

Volume is not a valid measurement because the density of each ingredient can vary greatly. Also, I was always curious what to do if the formula calls for 1 cup of cocoa butter (or similar ingredient). Cocoa butter is a brittle butter that can come in pellets, chunks or the whole block of butter.

So, how do we measure 1 cup of cocoa butter? Do we just add to the measuring cup until it is full? What about those gaps between pellets or chunks? Should we melt the butter and measure then?

But then again, how much should we melt so it will be just the right amount? This type of measurement makes more questions than it needs to be. And this is why we stick to the weight (oz or grams).



As mentioned before, the advanced cosmetic formulas will have all things from the simplified cosmetic formulas and will have some additions. Such as:

2.1. INCI name

Some ingredients in the common name may not be very specific in describing what exactly the ingredient is. For example extracts. They can be oil based, glycerin based, alcohol based on can be made with some other solvents. 

So, when you include the INCI name, you also include every other material that is in the extract. For example my Centella Asiatica extract INCI is Glycerin, water, Centella Asiatica extract.


This is an example of a more advanced cosmetic formula.


I know this can be frustrating to hear, but not ingredients are the same even when their INCI matches. Each ingredient can be made by a bit different method or can use a different variety of the starting material.

For example one carrier oil may not be the same as the other carrier oil from a different supplier. Their quality highly depends on the raw material, method of extraction, the weather, soil and many other things.

So to avoid the confusion, some formulators also write the manufacturer where they got the ingredient from (not the supplier as they may change their manufacturer).

2.3. Function

For easier formulation reading some formulators decide to write the function of the ingredient. It does help a lot even when you are a more experienced formulator as you can see a bit of reasoning why each ingredient was added.

For example for the Glyceryl stearate SE or Olivem 1000 or Polawax one can write the function as “Emulsifier”, for hyaluronic acid, glycerin – “Humectant”, Inulin – “Humectant, conditioning agent” etc.


  1. Potent

    What a great read. You always write great copy. Thank you so much. You do an amazing job.

    • Vaida

      It is very nice to hear that you found it useful. Thank you very much for the kind words – they keep me going forward. 🙂


Submit a Comment

Your email address will not be published. Required fields are marked *