How Long To Leave Hair Dye In: The Ultimate Guide

How Long To Leave Hair Dye In: The Ultimate Guide

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Are you wondering how long to leave hair dye in?

We have all been there.

You desired to make a change, so you went to the store to get some dye. But then you realized something. You missed this important detail.

Should you leave it too long or not?

How long to leave hair dye in?

Because you feared leaving it too long. It might end up bad. Or leaving it in a shorter period could lead to equally devastating results.

Perhaps it would end up in uneven color. Who wants that anyway?

So what do you do?

Woman in salon chair having her hair dyed

Wondering how to make sure the process went well without having to experiment with yourself a couple of times?

Well, I have great news for you.

If you want to know how long exactly to leave each hair color to get the best results, then this post is for you.

In this article, we will look into the secrets of the experts. How come they know how long to leave hair dye in?

Go ahead and check out this quick guide.

It lists everything.

From how long the waiting time is before you wash out the hair dye to when it will start fading away.

With this post, I hope you get a deeper understanding of everything you need to know down to the last detail.

Because there’s simply no need to agonize over simple decision-making processes.

Why proceed with hair dyes aimlessly or waste money on products that don’t give the results they promised?

In this guide, I got you covered.

So sit back and let this post lead you to the simple steps. Because, like me, I want you to enjoy gorgeous tresses every day of your life without hassle.

How Long to Leave Hair Dye On?

Here’s a quick set of pointers on how long to let dye sit in hair.

Want the short answer?

If it’s permanent or semi-permanent, you can leave the dye for around 30 to 45 minutes.

But if it’s henna, it will be longer. Around two to six hours of waiting.

Now, for the longer answer.

How long to leave hair dye in will depend on a couple of factors.

For one, the length and thickness of your hair.

You also need to consider what look are you trying to achieve.

Lastly, the brand or product you will use.

Typically, DIY coloring your hair at home should not take too long.

Generally speaking, here are the periods for each segment of the entire hair-coloring process.

  • 30 minutes, if you’re doing an all-over application on virgin hair
  • 30 minutes, if you want to include the roots on dyed hair
  • 30 to 40 minutes, waiting time for the dye to develop
  • 90 minutes or more, which accounts for the entire process

It will probably take more time to complete the process if your hair was dyed before.

Woman looking in the mirror dying her hair at home

How Long to Leave Hair Dye In for Different Hair Types

To truly give a close to a definitive answer on this subject, we need to go through the different hair types. I feel it’s only fair that we consider how certain hair types react to various chemicals.

That’s because permanent hair dyes have certain chemicals. These substances activate at particular time intervals after their application to your hair.

So you need to consider the specified time for these chemicals to sit on your hair so the hair dye can do its work.

For this reason, we will examine how long should permanent hair dyes be left in for the different hair types.

Grey Hair

Did you know it’s the most resistant to new pigment?

That’s because grey hair tends to have a dry and coarse texture. This means it’s naturally lacking in sebum, which is the natural oil we produced on our scalp.

As a result of the dryness and coarseness, this prolongs the process of depositing color on grey hair.

So if you sport grey or white hair, then prepare for a lengthy color change. Say 45 minutes.

Please note that in the first 15 minutes of the hair-coloring process, there’s a lot of chemical activity involved. Particularly, the main chemicals of the hair act to penetrate the cuticle layer of each strand. These chemicals include ammonia and peroxide.

In the last 30 minutes, this is when the hair dye’s chemical molecules develop. As a result, it imparts a new color to each strand.

If you’re working to cover the gray roots, it also follows the same chemical process.

Root Touch-Ups

Root touch-ups require a different processing time. More so, as it depends on the color you chose and your hair type.

However, in general, you need to leave the hair dye in for about 45 minutes if you are focusing on the roots.

Now, you may encounter a couple of stubborn grey strands that are resistant to color. Here’s what you can do.

Experts refer to this process as pre-pigmentation. This also requires 45 minutes to complete. Here, you will need to open the cuticle layer before applying the developer. For this purpose, you will use ammonia.

By focusing on pre-pigmentation first, you pave the way for the hair dye to penetrate deeper into each strand. When done right, the result is a vibrant color that lasts long.

Touch-Ups for Roots with Highlights

Same, 45 minutes. This is ample time to allow the touch-up to reach up to the roots if you have highlights.

It requires the same length of time because your roots need a longer processing time than ends or mid-lengths.

Plus, the roots with highlights are typically smoother and closed. That’s due to the chemicals previously applied to it. This is why there’s a longer processing time for roots with highlights.

What’s more, the chemicals used in the touch-ups require more time to penetrate through and inject the new hue.

Dark Virgin Hair

Do you have dark tones on your hair that’s never been processed before?

Then that makes for a quick color change.

Dark virgin hair only requires around 30 minutes of waiting time for the hair dye to settle in. That’s because this type of hair retains new color easier on account that it hasn’t been processed before.

Pre-Colored Hair

This one, however, takes a little bit longer than dark virgin hair to process.

Because it was previously processed, pre-colored hair already has synthetic pigments injected into it. So the new hair dye takes longer to settle in.

For pre-colored hair, you need to leave the hair dye for about 35 to 45 minutes.

How Long to Leave Hair Dye In Before Rinsing It Off?

Unfortunately, there is no exact length of time as to how long before you rinse the mixture off.

However, I can give you a general answer.

I’d say a good 30-minute window works for me. Plus or minus. It will depend on the hair color and type of hair dye I picked.

The good thing though is that most hair dye products come with instructions on its bottle or box. So you might want to refer to it for more specific information on how to use or apply it.

The package or container didn’t come with instructions on how long to leave hair dye in?

Here’s my rule of thumb.

Just keep checking on the dye at five-minute intervals until it looks or feels right.

You’ll know it’s right when you notice the change in color.

Test as often as you need until enough time has passed. And when you think it’s done, that’s the time to wash it out.


close up of hair dye being applied to roots by hair dresser

What Happens If You Leave Hair Dye in Too Long?

Apparently, there is some sort of time limit on how long to leave hair dye on. The longer the time passes, the higher the likelihood that the dye starts to lose its effectiveness.

What’s the time limit, you ask.

Well, it varies from brand to brand.

For instance, L’Oreal suggests letting the hair dye stay for about 30 minutes before washing it off.

On the other hand, Clairol recommends letting the color stay for about an hour before rinsing it out.

So what if you keep it longer, letting the hair dye stay beyond the recommended period?

To put it succinctly, it’s not a good idea.

Did you know leaving it too long can cause hair dryness?

You could also develop an allergic reaction due to the overstaying hair dye.

There’s also the itching of your scalp. If your scalp starts tingling, then there’s a good chance the hair roots are burned or saturated with the color.

In addition, you may suffer from hair breakage. Prolonged exposure to the hair dye (or any harsh chemical) can also cause your hair to become brittle.

This is why I strongly urge you not to leave any chemical treatment longer than is necessary.

Will Hair Dye Become Darker If You Leave It In Longer?


Your hair dye will not be darker in color even if you keep it in longer.

Rather, it’s the strength of the hair dye that determines whether it will be lighter or darker on your hair.

The processing time for hair dye is constant. So even if you leave your hair dye for two hours, it won’t result in a darker shade.

However, it can result in damage to your hair. That’s because prolonged exposure to harsh chemicals can do that to your locks.

Personally, I leave the hair dye in for less time. So if the instruction says to leave it in for 30 minutes, I just let it stay for 20 to 25.

Is Leaving Boxed Hair Dye More Effective?

No, it won’t have any substantial positive effect though.

Leaving your hair dye on overnight won’t deliver a darker finish.

Instead, it can lead to a large mess. The boxed hair dye will dry out. So washing it off your hair will only be more difficult.

As for your hair, it will tend to become dry.

Just follow the manufacturer’s instructions and you’ll be okay.

If you really want a darker shade, just go ahead and buy one from the store.

Will Leaving the Hair Dye In for a Shorter Time Result in Lighter Color?

Not necessarily.

However, one thing I would say about this is that the hair dye won’t permeate the hair.

Your hair dye requires a certain time to settle in. If you leave it for a shorter time, the color won’t develop completely.

But what if you wanted a lighter shade; what do you do?

You can add conditioner to the hair dye. That way, you dilute the formula. Just do this until you get the desired color. Then apply it on your hair and leave it in for the same recommended time as indicated in its instructions.

By diluting the hair dye, you get better results than leaving it for a shorter time.

How Long Do I Keep Hair Dye In?

Here’s what the experts are saying on how long to keep hair color in.

The American Academy of Dermatology recommends leaving the color in for about 20 minutes before you rinse it off.

At 20 minutes, your hair dye won’t cause damage to your hair. It won’t also irritate your scalp.

But if you’re looking for a quick color change, you can leave it on for about 10 to 15 minutes. That way, you don’t have to wait too long to get the desired hue for you hair.

However, please note that thick or curly hair, it’s a longer time frame. You may need to leave the hair dye on for 30 to 40 minutes.

Conclusion: How Long to Leave Hair Dye In?

Having new colors for the hair is cool. This explains why hair coloring is a trendy procedure that seemingly never goes out of style.

What’s great is that you can do this at home. Are you looking to color your hair at home too?

In all of these, you may need to undergo a lot of trial and error.

Because to truly comprehend how long to leave hair dye on involves multiple attempts. You can’t expect to perfect your hair-coloring technique in one go.

And if you don’t feel confident in coloring your own hair yet talk with your local hair dresser first. 

In time, you will find what works for you within your resources.

Hope this post answered your question on how long to leave hair dye in.

Here are some fun hair dye ideas: 

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