How Long to Leave Hair Dye in for Best Results

how long to leave hair dye in

Raise your hand if you have either thought of or tried to change your hair color at home. We’ve all been there, and it always seemed like a good idea at the time. Yes, DIY hair coloring can be fun, but it can quickly turn bad if you do not know how hair dyes work. Today, I will tell you more about the hair coloring process and exactly how long to leave hair dye in your hair!

I personally love going to the hairstylist — the joy of having a new, professionally done hairstyle is irresistible. I love feeling pampered, but there are also those days when I just do not have the time or the funds to have a professional do my hair for me. On those days, I turn to the internet and my go-to hair blogs to teach me how to achieve perfect hair without the help of a professional.

If you are thinking about coloring your hair at home, you have come to the right place. I’ll explain everything you need to know about the process, how long to leave hair dye in, what to avoid, and how to take care of your new hairstyle once you are finished. I will tell you all about the basics of hair dyeing and help you achieve the hair color you have been dreaming of!

Choosing Your Hair Dye

how long to leave hair dye in

If you want to change your hair color, you will need a cosmetic product that I’m sure you’ve heard of: hair dye. There are various types of hair color to choose from, as well as many colors to consider. When it comes to the types of hair color, you should know the differences between semi, demi, and permanent hair colors:

Semi-Permanent Hair Dyes

This type of hair dye lasts about three weeks, depending on how often you wash your hair. If you are still not sure you want to commit to a certain hair color, you can use this type of hair dye to give it a try but ultimately go back to the original color after a few weeks.

One of the best things about semi-permanent hair dyes is that they do not contain peroxide or ammonia, so you will not damage your hair if you choose to go with this type of hair dye.

Demi-Permanent Hair Dyes

Demi-permanent hair dyes are also ammonia-free, but they can last up to a month or even more if you wash your hair less often. This type of hair dye is usually used for toning or refreshing colored hair, but you can also use it to enhance your natural color if you still have completely natural hair.

Permanent Hair Dyes

Unlike the previous two options, permanent hair dyes contain both ammonia and peroxide. This type of hair dye permanently changes the color of your hair, and it is a common choice for covering grey hairs.


With this type of hair dye, you will need to repeat the dyeing process every two months to make your hair more vibrant. At the same time, you will need to retouch the roots once new hair starts growing.

It is crucial to understand the basic rules of applying permanent hair dye. Depending on how thorough you are and how long you leave the hair dye in, you can either achieve the results you want or make your hair an absolute disaster. To avoid hair catastrophe, I will tell you more about how long you should keep hair dye in your hair when changing your hair color!

How Long to Leave Hair Dye in

When you purchase a hair coloring kit, it will almost always come with detailed instructions on how to use the hair dye as well as how long to keep it in your hair. My first advice is to check the instructions on your specific type of hair coloring kit and follow those instructions.

The general rule of hair dyeing is to keep the hair dye in your hair anywhere from 30 to 45 minutes. Anything less than that will result in a hair color different from the one you are expecting, while anything more will unnecessarily damage your hair.

It takes 30 minutes for the hair dye to permeate your hair — simply said, to fully develop. The following 15 minutes allow the peroxide and ammonia to seep into your hair strands. After 45 minutes, your hair has changed color and the hair dye can be rinsed out.

Keep in mind that the hair dyeing process is not one-size-fits-all. Even if you follow the instructions, the state and texture of your hair can influence the final results. To avoid any unwanted mix-ups, I will also tell you about the factors that play a part in how long you should leave dye in your hair.

Hair Color History

Natural Hair Color

Natural hair is hair that has never before been chemically treated or colored. Before dyeing natural hair for the first time, you should consider the color that you have as well as your skin tone to determine which color will suit you best.

When dyeing natural hair, you can leave the hair dye in for 30 minutes for finer hair and 45 minutes for more textured hair. Leaving the hair dye on for longer can lead to hair damage.

Hair that has never been dyed before tends to be easier for dyeing, and following the dye kit instructions will be enough to get the color you want. However, you should be aware that the hair dye will damage your hair. It could be months or years before you can grow out the colored hair and return to your original hair color, so you should be prepared for that as well!

Current Hair Color

If your hair has previously been dyed, that can affect your next hair dyeing. The best practice is to use a color remover to remove the existing artificial color before using the new hair dye.

Also, be careful if you have hair that is colored in some areas and natural in others. Using a new hair dye on these varied parts will give you different results, so you should consider trimming the part with artificial color or using color remover before adding the new color.

When dyeing already colored hair, you should leave the hair dye in your hair for 45 minutes to get the best results.

Gray Hair

Father Time catches up with all of us at some point — if you are starting to see some grey hairs pop up and you want to get rid of them, you should use permanent hair color to cover them.

I recommend leaving the hair dye in for about 45 minutes before you rinse it out. That should be enough to target those grey hairs and create a seamless, grey-free look.

Hair Thickness

Finer hair tends to damage faster. As a result, you might need to rinse your hair dye out after only 30 minutes. Leaving the dye to process for 45 minutes might lead to over-processing and damage.

On the other hand, if you have thicker hair, you will need to leave the hair dye to process for the full 45 minutes. Make sure that you cover your entire hair with the dye, and don’t be afraid to use more of the product if you want to avoid spotting!

Hair Porosity

Hair porosity simply means your hair’s ability to absorb moisture. If you have very porous hair that absorbs the dye quickly, you can rinse the hair dye after only 30 minutes of processing. However, if your hair has low porosity, you will need to leave the hair dye on for 45 minutes.

What If You Leave Hair Dye in for Too Long?

There is a common misconception that leaving hair dye in for longer will result in better hair color. This is not true — leaving the hair dye for too long will not give you any special result; it can only unnecessarily damage your hair.



Some hair dye kits can automatically deactivate after 45 minutes. That means that they will not do anything more to your hair once they are done with the processing time.

However, some will damage your hair and leave it looking burnt and dreadful.

Maybe you did not know that you were not supposed to leave the hair dye in your hair for longer than instructed — it happens, and there is no need to worry. You can do several things to bring the glory back to your hair.

Pamper Your Hair

You can do this even if your hair is not damaged or colored at all — it is always nice to nourish your hair and make it look even better.

Some of the best hair treatments you can give yourself are DIY natural hair masks with coconut oil, extra virgin olive oil, or any kind of nourishing oil you like. They will make your hair smoother and shinier in no time!

Steer Clear of Hot Tools

If you dyed your hair recently and you find it looking a bit damaged, you should definitely consider parting ways with your hot tools for some time. That means no flat irons, curlers, or hairdryers!

Get a Trim

If your hair looks damaged beyond repair, getting a trim might be the only solution for you. You can either cut the ends only or try a shorter hairstyle that you have always thought about but never got to do. Once you get that trim, you can start using nourishing treatments to make your hair look healthier.

Hair Dye FAQs

Even after reading everything and anything hair dye-related you could get your hands on, there might still be some lingering questions in the back of your mind. So, let’s see what other people asked that you might also be asking yourself:

Can I leave hair dye in for two hours?

As mentioned previously, most hair dye kits tend to deactivate after 45 minutes of processing. This means that leaving the dye on your hair for two hours or longer will do absolutely nothing positive to your hair. It might only damage it unnecessarily. Be sure to read the instructions on your dye to confirm that your dye is safe to leave on for that time.

Why do stylists hate boxed hair color?

If you seek advice from a professional before dyeing your hair, they will inevitably advise you not to use boxed hair dye because of the high amounts of henna, ammonia, and metallic salts. Most of the chemicals used in boxed hair dyes can lead to skin rashes or other types of reactions and could also damage your hair.

A healthier, less damage-prone option is to have a professional dye your hair with a professional hair dye or try using such a hair dye by yourself. It will give your better results than boxed dye while also saving your hair from damage.

Can you get your hair professionally dyed after box dye?

You should wait at least a few days, preferably a few weeks, before you color your hair again after using box dye. You can turn to a professional to help you achieve the color you want, but using box dye might make that a bit harder.

When you use box dye, you do not actually know what you are applying to your hair. What level of developer does the dye use? How many chemicals does it contain? This is why a professional hair dye is better — it can be tailored to your hair, less damaging, and easier to maintain.

You Can Dye Happy

If you followed this article closely from beginning to end, you are ready to dye your hair and do it in the best, safest way possible. By now, you should know how long to keep hair dye in your hair and how to avoid damaging your hair.

Thank you for sticking with me through this article. If you have any interesting hair dyeing stories or tips for those still contemplating a change of hair color, please share them in the comments below!

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