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How to Dilute 40/30/20 Volume Developer?

aida turner

Published by Aida Turner

Fact checked by Annie

Coloring or bleaching your hair is a complex process involving deciding the shade and choosing the right hair developer. The developer contains hydrogen peroxide and is used to open up your hair cuticles so that the color deposit on your hair shaft is permanent.

The best way to dilute hair developer is by mixing it with distilled water or tap water in the right proportion, until the components are fully combined. I don’t recommend using shampoo or conditioner for diluting a developer because it can disrupt the chemical balance of the mix, diminish color effectiveness, and cause uneven coloring or hair damage. You can dilute a higher-level developer to a lower level, not vice versa.

The strength of the developer is measured either as a percentage (3, 6, 9 or 12% hydrogen peroxide) or in volume units (10, 20, 30 or 40 Vol.). A higher number signifies a stronger developer, enabling it to lighten the hair more effectively. This means buying a 40-volume developer is sufficient to get the effects of a 40, 30, 20, or 10-volume developer.

Now you must be wondering if you can buy developers of different strengths, why bother diluting them at all? In this article, I will show you why it is a good idea and how you can quickly dilute different developer volumes.

Why Should You Dilute a Developer?

There are several reasons why you want to buy a higher volume developer and dilute it, here are the five most important ones:

  • More flexibility: Buying a higher-level developer, such as a 40-volume developer, allows you to dilute it to lower levels as needed. This means that a single purchase can serve multiple purposes, providing the effects of a 40, 30, 20, or 10 volume developer as required.
  • Lack of availability: You might don’t find the needed developer volume in a strore, so your only option is to buy a stronger one and dilute it.
  • Hair Health Consideration: Hair developers are known for easily damaging your hair, so if your hair is already dry or breaking, diluting the developer to a lower level gives your hair a higher protection.
  • Desired Color Change: When your goal is a mild color shift, a potent developer might be overly aggressive. Weakening it gives you the subtle effect without overly lightening or damaging the hair.
  • Saves you money: Buying a higher-volume developer and diluting it as needed can be more cost-effective than buying multiple developers of different volumes

How to dilute different developer volumes?

To dilute specific developer volumes, mix the hair developer with water in the below proportions:

40 volume developer to 30

To get a 30 from a 40 volume developer , combine 3 parts of 40 volume developer with 1 part of water – in a 3:1 ratio 

40 volume developer to 20

Combine 1 part of 40 volume developer with 1 part of water to get a 20 volume one. The ratio followed is 1:1.

We are basically diluting half part 40 volume developer with half part water to get a 20 volume developer.

40 volume developer to 10

To get a 10 volume developer from a 40 volume one, we need to significantly dilute the 40 volume developer, in a ratio of 1:3 – that is mixing one part of water with 3 parts of 40 volume developer.

30 volume developer to 20

The ratio for getting a 20 volume developer from a 30 volume one is 2:1. This means mix 2 parts of 30 volume developer with 1 part water.

30 volume developer to 10

Mix 1 part of 30 volume developer with 2 parts water to get the 10 volume developer from a 30 volume one.

The ratio is 1:2.

Using the 30 volume developer only is recommended if you have a dark hair tone. In case, you have previously bleached or your hair is relatively brittle, it is best to use a low-volume developer. 

20 volume developer to 10

To dilute a 20 volume developer to 10, combine 1 part of 20 volume developers with one part water. The ratio is 1:1.

This means mixing equal parts of a 20 volume developer with equal parts of water will give you a 10 volume one.

10 volume developer to 5

To dilute a 10 volume developer to a 5 volume one, use a 1:1 ratio of developer to diluent.

How to make a 15 volume developer?

To make a 100ml of 15 volume developer with diluting only, you have three options:

  • mix 37.5 ml of 40-volume developer with 62.5 ml of water (or a 0-volume developer)
  • mix 50 ml of 30-volume developer with 50 ml of water, in an 1:1 ratio
  • mix 75 ml of 20-volume developer with 25 ml of water, in an 3:1 ratio

How to make a 25 volume developer?

To make a 100ml of 25 volume developer with diluting only, you have two options:

  • mix 62.5 ml of 40-volume developer with 37.5 ml of water
  • mix 83 ml of 30-volume developer with 17 ml of water

What to watch out for when diluting a developer?

When diluting a developer for hair dye, there are several factors to consider to avoid mistakes and potential damage to your hair and scalp. Here are some key points to watch out for:

  • Choose non-metallic tools: Utilize non-metallic containers and utensils, like plastic or glass, to avoid unwanted chemical reactions that can impact the color result.
  • Protect Your Skin and Eyes: The California Board of Barbering and Cosmetology recommends using gloves, safety glasses, and aprons when working with chemicals like developers. They also suggest using good ventilation to reduce exposure to harmful fumes.
  • Blend Thoroughly: Ensure a uniform mix of the developer and dye or conditioner to avoid uneven color application and to safeguard against potential hair damage.

What are the risks of not diluting developer properly?

Improper dilution of hair developer during the dyeing process can pose several risks, such as achieving a lighter, short-lived color, and experiencing uneven, patchy results. Putting too much developer in hair dye can damage hair cuticles and lead to a dull, dry, and brittle texture, while an overly strong developer can excessively lift the cuticle.


Can I dilute an oil-based developer?

Yes, you can dilute an oil-based developer, but the materials used and the process differ from diluting a water-based developer.

Can I mix different brands of developer when diluting?

Yes, technically you can mix together different brands of developer when diluting, but I don’t recommend itunless you’re well-versed in using hair dyes. Different developers can have varying ingredients and strengths, which might lead to unexpected and undesirable results, like an inconsistent mixture or patchy color. Always prioritize using the same brand to ensure consistent and reliable results in your hair coloring process.

Can I dilute semi-permanent hair dye?

Yes, you can dilute semi-permanent hair dye, too. It will give you a lighter, more subtle color, which is great if you’re going for a soft pastel look. Plus, it can make your dye last longer, so it’s a bit friendlier on the wallet. But keep in mind, not all dyes are meant to be diluted. Some, especially those two-part dyes where you mix color and developer, or box dyes, are meant to be used just as they are.

Can I use hair dye without a developer?

No, I don’t recommend you to use hair dye without a developer, unless you are using with semi-permanent hair dye products.

aida turner

Author of this article: Aida Turner

Founder & Hair Care Consultant

Aida is a cosmetologist and hair care consultant with over 7 years of experience in the beauty industry. Aida has worked with various top salons and smaller hair care brands, offering her product development, formulation, and testing expertise.

Her extensive knowledge of hair care ingredients and their effects on hair health enables her to provide thorough, well-researched, and unbiased reviews on a wide range of shampoos and hair care products. In her spare time, Aida enjoys experimenting with new hair care routines, blogging about her experiences, and helping others achieve their hair goals.