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How to Dilute Developer | Step-by-Step Guide

You’ll need a high-quality hair developer to get the job done when you’re lightening your hair. There are several developer volumes to choose from, like 10, 20, 30, and 40. Each volume developer has a slightly different job, and its strength increases as the numbers increase.

Developers help lift your hair by various levels depending on the level, your hair’s current level, and how long you leave it on your hair.

Most people think you can only use a developer when bleaching your hair, but many hair stylists also use it when applying hair color. There are many reasons why you might need to dilute your hair developer.

Maybe you found a 40-volume under your sink and don’t want it to go to waste. Or, perhaps you were at a hair supply store, and all they had was a 40-volume, and you’re in a rush to do your hair. 

Regardless of your reason for needing to dilute your hair developer, knowing how to do so can be life-saving for your hair.

The good news is that diluting your hair developer is surprisingly much easier than you might think. If you find yourself in the position where you need to do so, here’s how you can dilute developer to use on your hair. 

Diluting Hair Developer: A Summary

Diluting your hair developer isn’t as hard as you might think it is. What you’ll need to dilute the developer is a developer, water or conditioner, a bowl, and a brush you’ll use to apply it and mix it.

Once you’ve gathered your supplies, all you’ll need to do to dilute the developer is: 

  1. Measure your developer
  2. Pour the developer into the bowl
  3. Measure your water or conditioner
  4. Pour the water or conditioner into the bowl 
  5. Mix to combine

For the sake of this article, we’ll focus on how to dilute 40-volume developer to 20-volume. That being said, if you have 30-volume and want to dilute it to 10-volume, you can do so with the exact same steps as you would with changing 40 to 20-volume. 

Even if you have a 20 or 10-volume developer, you can dilute it further if you want, but that’s less likely than diluting 40 and 30-volume developers.

Using a 10-volume developer is ideal if you’re depositing hair color and not looking to lift the hair. It can provide minimal lift, but depending on your current hair color, you might not see any lifting at all. 

If you have 40 and 10-volume developers but are looking to have a 30-volume, you can dilute the 40-volume by adding two parts of the 40-volume to one part of the 10-volume.

Using 40-volume and 10-volume to cut to 30-volume is much less common but worth mentioning in case you have these products on hand. If you aren’t sure which level is best on your hair, read our guide on “which hair developer to use.”

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How to Dilute Developer in 5 Steps

You don’t need to be a mathematician or hair stylist to learn how to dilute hair developer. You’ll want to use a ratio of 1:1 when diluting hair developer. Here’s how you can cut your 40-volume developer to 20-volume in only five quick steps. 

1. Measure Your Developer

The first thing you’ll want to do when diluting your developer is to measure how much of the developer you’ll need. How much you’ll need will depend heavily on how much of your hair you’re trying to lift and how long your hair is.

It also depends on if you’re mixing your diluted developer with bleach or a hair pigment. For the purpose of this tutorial, let’s say you’ll need 100 ml of the developer to lighten your hair. You’ll want to measure out 100 ml of developer into a measuring cup.

If you’re using a scale and converting the milliliters to grams, you’ll still measure out 100 grams. Keep in mind that you can change the amount of developer you need based on your hair. 100 ml might not work for everyone.

You’ll want to research the amount you’ll need, or you might find yourself with an excess of diluted developer or having to remix some in the middle of applying, which can cause an uneven application since you’re pausing.  

2. Pour the Developer Into a Bowl

Once you’ve measured out the amount of developer you’ll need, you’ll want to pour it into a bowl that’s large enough to fit the developer and water or conditioner later on. 

3. Measure Your Water or Conditioner

Now it’s time to measure out your water or conditioner, whichever you’re using to dilute the developer. Most people use water, but you can use a conditioner if you choose. So, if you measured out 100 ml of the developer, you’ll measure out 100 ml of either liquid. 

While it’s possible to use conditioner to dilute your developer, most people opt for water because using conditioner might cause your lifting or color to come out uneven.

Read Next: How to Mix Hair Dye With Conditioner

4. Pour the Water or Conditioner Into the Bowl 

Next, you’ll want to pour your water or conditioner into the same bowl you added your 40-volume developer. Be careful pouring the liquid into the bowl because if you pour it too fast, it could splash and slightly change the ratio of the developer to water or conditioner.

5. Mix to Combine

After you’ve poured the developer and your water or conditioner into the bowl, it’s time to mix. You’ll want to mix them with a dye stir or applicator brush. How long it will take to combine the two depends on how fast you stir and how well they blend. 

You’ll want to keep mixing until you have an even consistency. If you don’t have an even consistency, when you apply it to your hair, some pieces might get more water than the developer, or vice versa.

If this happens, you probably won’t be thrilled about how your hair looks when you rinse the product. Now you’re ready to mix the diluted developer with a lightener or hair color and apply it to your hair! 

Frequently Asked Questions

Image for a piece titled how to dilute hair developer featuring a woman pouring conditioner into her hand


It’s normal to have several questions when it comes to mixing hair products due to the chemicals. If you’re still curious about diluting developers, here’s what others are asking about the process. 

Can you mix conditioner with a developer?

Absolutely! You can mix conditioner with a developer to make it slightly less damaging to your hair. Remember, if you choose to do this, you’ll dilute the developer, so you might need to change how long you let it sit on your hair. Using conditioner rather than water can also cause your hair color’s life span to decrease.

Can you add water to the hair developer?

Yes, you can. You can add water to the hair developer if you want the color to be a typical deposit-only gloss. You’ll pour out half the developer and add the same amount of water back into the bottle or bowl. You’ll mix it and distribute it throughout your hair before rinsing. Using water is more common than conditioner.

Do you have to dilute the developer?

You don’t have to dilute the developer, but most people do so when they want to lower the developer’s potency. It’s a good idea to avoid frying your hair, but if you’re comfortable working with a higher volume developer, you don’t need to dilute the product.

Can a 20-volume developer lighten hair by itself?

Yes, it can. Putting a 20-volume hair developer on your hair alone can lighten it, but it will only do so by about one level. For example, if you have a level 4 light brown, using this developer by itself can lighten it to only a level 5 dark blonde. Using a 20-volume developer is fine if that’s your end goal, but if you want it lighter, you’ll need a higher volume developer.

What happens if you put a developer on your hair by itself?

When using a developer, you should always mix it with a lightener to get the best results. You can still put hair developer on your hair by itself, but you won’t get the results you’re looking for. If you do this, the product will open the cuticle, and some of the hair’s melanin will come out and lighten the hair, but it won’t look that great.

So, How Do You Dilute Developers?

Diluting developers is more common than you might think. It’s helpful when you can’t find the volume you want or need for a specific hair color or bleach. You don’t need to be a hairdresser to learn how to dilute developers or have any special skills.

As long as you remember the ratio of 1:1, you’ll be good to go. To dilute hair developer, you have to know how to measure using a measuring cup or scale.

Regardless of which volume developer you need to dilute, you’ll want to use water or conditioner in a 1:1 ratio. Once you do this, you’ll be ready to apply it to your hair and get your hair looking how you want.