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How to dilute 40 volume developer to 30/20?

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.

In the realm of hair coloring, achieving the perfect shade often requires the precise use of developers. However, situations may arise where you need to adjust the volume of your developer for various reasons. This comprehensive guide will delve into the process of diluting a 40 volume developer to 30 or 20 volumes, ensuring you understand the steps involved and the potential outcomes. 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
  • Controlled Lightening: Diluting the developer allows for more controlled lightening. It slows down the lightening process, giving you more time to monitor the color change and prevent over-processing.
  • Reduced Sensitivity: Diluted developers are often less harsh on the scalp, reducing the likelihood of irritation or sensitivity reactions during the coloring process.
  • Customization: Different hair types and colors may require different developer strengths. Diluting the developer allows for customization, ensuring that the lightening process is tailored to the specific needs of the hair.

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 

Diluting a 40 volume developer to 30 volume involves a straightforward process. Here’s a step-by-step guide:

  1. Gather Your Materials: You’ll need a measuring cup, 40 volume developer, distilled water, and a mixing bowl.
  2. Measure the Developer: Pour the desired amount of 40 volume developer into the mixing bowl. Be precise in your measurements to ensure the desired outcome.
  3. Add Distilled Water: Gradually add distilled water to the developer, stirring gently as you go. The ratio of developer to water will determine the resulting volume. To dilute to 30 volume, you’ll typically mix equal parts of 40 volume developer and distilled water.
  4. Mix Thoroughly: Stir the mixture thoroughly to ensure that the water and developer are well combined. This will ensure an even distribution of the active ingredients.
  5. Test the Mixture: Before applying the diluted developer to your hair, perform a patch test on a small section to ensure that it achieves the desired lightening effect without causing excessive damage or irritation.

By following these steps, you can effectively dilute a 40 volume developer to 30 volume, allowing for a gentler lightening process while still achieving the desired hair color results.

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.

Gather Your Supplies:

  • 40 volume developer
  • Distilled water
  • Mixing bowl
  • Measuring cup

Calculate the Dilution Ratio:

  • Determine the desired ratio of 40 volume developer to distilled water. For example, a 1:1 ratio will result in a 20 volume solution, while a 1:2 ratio will result in a 10 volume solution.

Measure the Developer:

  • Pour the desired amount of 40 volume developer into the mixing bowl. Use the measuring cup for precision.

Add Distilled Water:

  • Gradually add an equal amount of distilled water to the mixing bowl. For example, if you poured 2 ounces of developer, add 2 ounces of distilled water.

Mix Thoroughly:

  • Use a stirring tool to mix the developer and distilled water thoroughly. Ensure that the mixture is uniform and free of any clumps or streaks.

Perform a Patch Test:

  • Before applying the diluted developer to the entire head, perform a patch test on a small section of hair. This will help you assess the lightening effect and ensure that it meets your expectations.

Adjust as Needed:

  • If the patch test results are satisfactory, proceed with applying the diluted developer to the entire head. If not, adjust the dilution ratio accordingly and repeat the process until the desired results are achieved.

Monitor Processing Time:

  • Keep a close eye on the hair’s lightening progress during the processing time. Since the developer is diluted, it may take longer to reach the desired level of lightness compared to undiluted developer.

Rinse and Condition:

  • Once the desired lightening level is achieved, rinse the hair thoroughly with lukewarm water and apply a deep conditioning treatment to restore moisture and nourishment.

Repeat as Necessary:

  • Depending on the initial hair color and desired lightening level, multiple applications of diluted developer may be necessary. Repeat the process as needed, always prioritizing the health and integrity of the hair.

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
  • After adding the distilled water, mix the solution thoroughly to ensure even distribution. It’s crucial to maintain accuracy in measurements to achieve the desired volume accurately.

    Before applying the 15 volume developer to your hair, perform a patch test to check for any adverse reactions and to gauge the lightening effect. Adjust the dilution ratio if necessary based on the results of the patch test.

How to make a 25 volume developer?

Creating a 25 volume developer involves a precise blending of 40 volume developer with a suitable amount of distilled water to achieve the desired potency. To start, gather the necessary materials: 40 volume developer, distilled water, a measuring cup, and a mixing bowl. Begin by measuring out the required amount of 40 volume developer into the mixing bowl. Next, calculate the dilution ratio; for a 25 volume solution, you’ll need to mix one part 40 volume developer with one part water. Gradually add the distilled water to the mixing bowl, ensuring a thorough blend with the developer. Stir the mixture well to ensure uniformity. Before use, conduct a patch test to evaluate the lightening effect and ensure compatibility with the hair. Adjust the dilution ratio if necessary based on the patch test results. With careful measurement and testing, you can create a customized 25 volume developer tailored to your specific hair coloring needs.

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.

Hair Damage: Undiluted developer, especially high-volume ones like 40 volume, can cause excessive damage to the hair. It can lead to over-processing, resulting in dryness, breakage, and even hair loss. Without proper dilution, the developer may strip the hair of its natural oils and weaken its structure, leaving it brittle and prone to damage.

Scalp Irritation: Concentrated developer can be harsh on the scalp, causing irritation, redness, and discomfort. The strong chemicals in undiluted developer may cause chemical burns or allergic reactions if they come into direct contact with the scalp. Proper dilution helps to reduce the risk of scalp irritation and ensures a more comfortable coloring experience.

Uneven Results: Using undiluted developer can result in uneven color results and patchiness. The high potency of the developer can cause certain sections of the hair to lighten more quickly than others, leading to an uneven or splotchy appearance. Diluting the developer allows for more controlled and even lightening, resulting in consistent color results throughout the hair.

Unpredictable Color Outcome: Without proper dilution, the color outcome may be unpredictable and may not match the desired shade. The potency of the developer can alter the intended color, leading to unexpected or off-tone results. Diluting the developer ensures that the color outcome is more predictable and aligns with the desired shade.

Overall, failing to dilute developer properly can result in various risks, including hair damage, scalp irritation, uneven color results, and unpredictable outcomes. It’s essential to follow the recommended dilution ratios and procedures to minimize these risks and achieve the desired hair color safely and effectively.

Is it Possible to Dilute Developer with Conditioner?

Yes, it is possible to dilute developer with conditioner, although it’s not the most common method. While conditioner can help mitigate some of the harsh effects of the developer, it may not provide the precise dilution needed for consistent results. Additionally, the conditioner may contain ingredients that could potentially interfere with the chemical process or alter the final color outcome. For best results, it’s recommended to dilute developer with distilled water, as it ensures a more accurate and controlled dilution without introducing any additional variables that could affect the color result.


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 dilute developer with any type of water?

It’s recommended to use distilled water to dilute developer as it lacks impurities found in tap water, ensuring a more precise mixture.

Will diluting developer affect color results?

Diluting developer may slightly alter color results, but it’s a necessary compromise to minimize damage, especially on previously processed hair.

Is it safe to dilute developer at home?

Diluting developer at home is generally safe if done correctly. However, it’s crucial to follow instructions carefully and perform patch and strand tests to avoid unwanted outcomes.

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.