How Long to Leave Bleach in Hair? Plus Proper Steps

Bleaching your hair at home seems like a daunting task, but it’s not, as long as you know what you’re doing. The most important thing you should know is how long to leave the bleach in your hair. If you leave bleach in your hair for too long, it can damage it and make it much lighter than you want.

How long to leave bleach in hair? Bleach should be left in your hair for any time between 15 and 30 minutes. The amount of time varies depending on your hair’s current color, the thickness of your hair, and how light you want it to become. You should first do a small strand test to know exactly how long to leave it in for.

For example, if you have black hair and you want to go full-on blonde, you will need to leave bleach in your hair longer. If you have brown hair and want to go a few shades lighter, it will only take a few minutes for the bleach to lighten your hair.

Keep reading to learn more about how long to leave bleach in hair, as well as some useful tips to help you safely and successfully change your hair color at home!

What is Hair Bleaching?

Hair bleaching is a process involving the use of chemicals to remove the natural color of hair.

Bleaching also works in removing artificial hair color, for example, if you want to remove previous hair dye and you want to start over. This is a required step to prepare the hair for coloring, usually for lighter shades. For example, if you dyed your hair dark brown and you want to go blonde, you need to bleach your hair first to remove the dark brown dye, and then proceed to coloring your hair blonde.

How Long to Leave Bleach in Hair? Plus Proper Steps

how long should you leave bleach in hair

Bleaching is a serious process that your hair will go through. The bleaching chemical works by penetrating your hair shaft and oxidizing the pigments that give your hair its natural color.

You’re basically damaging your hair through this process, which is why you really need to prepare your hair before bleaching it. If your hair has been damaged from a previous treatment, it’s best to get your hair into a healthy state before bleaching. To get your hair into a healthy state, it’s essential to use a good conditioner.

My wife swears by the R+Co Television Perfect Hair Conditioner (click to see price and reviews on Amazon) for keeping her hair soft, hydrated and healthy all year long. This conditioner is formulated for giving body, shine, and strength to dry, damaged, tangled, or frizzy hair.

If you condition your hair and really take care of it for a few months before bleaching it, your hair should be just fine. If it’s already in a healthy state, keep conditioning it for a week or so before bleaching.

The top-rated hair bleach on Amazon is the Clairol Professional BW2 Lightener (click to see price and reviews on Amazon). It is an extra-strength bleach, which means it doesn’t take as long to get to the brighter shade you desire. It has a creamy consistency and is dedusted which means there won’t be any excess powder flying off your hair. Clairol recommends using it with a 10 or 20-volume developer.

To bleach your hair, you will need a developer for the bleach to lighten your hair. Developer contains hydrogen peroxide which opens up the cuticle of your hair, allowing the bleach to hold and strip the natural color away. You also need a developer if you use a hair dye to color your hair a different color.

The top-rated hair developer on Amazon is the Schwarzkopf Professional Blonde Me Premium Developer (click to see price and reviews on Amazon). The 20 volume option is a safe choice as 30 or 40 can damage your hair fairly quickly. I’ve bleached my hair before using a 30 developer and my hair was much too dry after using it.

After your hair is well-conditioned and in a healthy state, it’s time to bleach it. Here are the steps you need to follow:

  1. Change into some old clothes that you won’t care about getting bleach on. Also, put on your gloves.
  2. Divide your hair into sections so that you can get the bleach in your hair evenly. This also means you can work with your hair easier.
  3. Prepare your bleach powder and the developer. The general ratio is two parts of the developer to one part of bleach. Mix well so that there are no lumps.
  4. Apply the solution from the middle to the tips of your hair, since the middle takes a longer time to lighten. You can undo the hair sections you did earlier as you go along. You can then apply bleach to your roots to get an even color.
  5. Leave the bleach in your hair for approximately 15 to 30 minutes depending on how bright you want it to be. Set a stopwatch or a timer so that you don’t lose track of time.
  6. When you’ve finished all of your hair, cover it with a shower cap or a plastic bag. Leave the bleach on depending on the results of your strand test, or depending on what you want to achieve. Either way, you should not leave bleach in your hair for more than 30 minutes.
  7. Wash and condition your hair and let it air dry. You’re done!

Bleach works best for virgin hair. If you have black or dark hair, or if it has been colored before and you want to go several shades lighter, you may need to bleach your hair several times before you get the shade you want. You’ll need to schedule these bleaching sessions around a month apart so that you avoid permanently damaging your hair.

Even if you have virgin hair but it’s very thick or very fine, or if it was permed or damaged from a previous treatment, it would be best that you have your hair bleached by a professional. In this way, the results will be as close as what you want it to be, and to avoid unnecessary damage to your hair.

The below video gives a great tutorial on how to bleach hair at home, including how long to leave the bleach in your hair:

Why You Should Do a Strand Test

What is a strand test? Well, simply put, a strand test is when you apply the bleach on a few strands of your hair and carefully keep an eye on the time until you get the results you want. Basically, what you need to do is to prepare a small amount of bleach, and then dab it on a couple strands of hair. Choose the ends, because you can always cut it out if you don’t like it. 

Keep checking your hair every 2-3 minutes to see the shade it’s turning into until you get the shade you want. Keep a note of how long you’ve had the bleach in your hair as well – this will be the time that you’ll use when you bleach the rest of your hair.

Do you really need to do a strand test? No, not really, especially if you already bleached your hair before and you know what you’re doing. But if you’re new to this, or if you want to go lighter than you’ve gone in the past, then a strand test is a must. The last thing you want is severely damaged hair or much lighter hair than you desire.

What to Do If You Left Bleach in Your Hair for Too Long

So maybe you accidentally dozed off, or you forgot to set an alarm and left the bleach in too long – what do you do? Here are a few things you should do if you left bleach in your hair for too long.

  1. Don’t shampoo your hair for a day or two. Bleaching will dry your hair out, and you want to save as much of your natural oils as possible. If you shampoo your hair, you’ll lose these oils. It is safe to condition your hair though.
  2. Use an intensive hair conditioning treatment with every other wash like hair oil or cream mask before you shampoo. Or, you can apply the treatment and then wrap your hair in a towel and then go to sleep. Rinse it in the morning and you can shampoo and style your hair as you normally would.
  3. Use a leave-in conditioner every day to help keep your bleached hair moisturized. This will help keep any frizz under control.
  4. Use a protein mask for a week after bleaching your hair, especially if it’s very brittle. You can make your own protein mask by mixing one egg and a spoonful or two of yogurt. You’ll need to leave the mask for 30 minutes, and then rinse with cold water.
  5. Dry your hair with an old shirt or a microfiber towel. Don’t brush it if it’s still wet. You should also avoid rubbing your hair with a towel and just let it air dry.
  6. Take a flaxseed oil supplement or fish oil capsules to promote healthy hair growth.

If possible, you should have as much of the damaged hair cut off. If your hair is breaking in the middle, ask your stylist for a haircut that will help hide the different lengths of your hair. If you don’t want to go super short, you can always have about a quarter of an inch trimmed off every month so you can get the damaged parts out.

Also, avoid exposing your hair to too much sun, as well, skip blow dryers, hot irons, and curlers while you give your hair time to heal. A simple hairstyle that won’t pull or tug at your hair excessively would also be ideal.

Common Mistakes When Bleaching Hair at Home

how long to leave bleach in hair 20 vol
Damaged hair from leaving bleach in too long

Most professional hairstylists do not recommend bleaching your hair at home, as it is very easy to make a mistake and damage your hair. But if you’ve done it before, or you know what you’re doing, you should already be familiar with common mistakes when bleaching hair at home. Avoid the below mistakes when bleaching your hair DIY-style.

1. Not Having Everything You Need Ready and On-hand

You should have old clothes, gloves, mixing bowl, dye brush, powder or cream bleach, hair clips to part your hair with, developer, toner, conditioner. The last thing you want is multiple trips to the store because you keep forgetting something.

2. Not Reading Labels and Instructions

Make it a habit to always read the labels and instructions of the products you use, even if you’ve used them before. This helps in ensuring you won’t make any mistakes when bleaching your hair.

3. Not Performing the Strand Test

The strand test gives you the exact time you need to leave bleach in hair to get the results you want. Moreover, the strand test also helps you discover whether you’re allergic to any of the products you’ll be using before you use them on your entire head.

4. Bleaching Your Hair by Yourself

A second pair of eyes and hands never hurt anyone. Having someone over when you bleach your hair will make sure you don’t miss any spots, you don’t forget the time, and you get all the hard to reach places.

5. Leaving Bleach in Your Hair for Too Long

Always follow the instructions on the products you use. If you know someone who left bleach in their hair for a really long time and it worked for them, don’t do it. Your hair is different, and you might not get the same results. If you leave the bleach in for a really long time, you could burn your scalp and have permanent hair damage.

6. Not Deep Conditioning Your Hair Before Bleaching

Your hair will thank you if you start deep conditioning it weeks before you bleach your hair. It will help strengthen your hair and balance out the damage bleaching causes.

7. Not Checking Your Hair’s Condition and Texture

If you’ve recently bleached your hair or if you’re in doubt as to whether it can handle bleaching, you should check your hair first before doing anything. You can ask a professional and follow their advice. If you’re told to wait for a few months, and regularly condition your hair first, just do it. Doing so will ensure you get great results and your hair will thank you.

If you have damaged hair, getting a professional’s advice is the best way to go. You should avoid using any blow driers, hair straighteners, or curling irons that could cause more damage. Regularly use deep conditioners, coconut oil, and hair masks to help condition and strengthen your hair.

Conclusion – How Long to Leave Bleach in Hair

Bleaching your hair at home seems like a daunting task, but it’s not, as long as you know what you’re doing. As long as you know how long to leave the bleach in your hair, that is most important. This is to avoid any unnecessary hair damage and so that you get the results you want.

How long to leave bleach in hair? You can leave bleach in your hair between 15 to 30 minutes. This time varies depending on how thick your hair is, as well as the current color, and how light you want it to become.

If you have black hair and want to go full blonde, you will need to leave the bleach in your hair for longer – closer to the 30-minute maximum time. If you have brown or strawberry blonde and are looking to get a few shades lighter, the bleach will only have to stay in your hair for a few minutes.

To properly bleach your hair, follow these 7 steps:

  1. Wear old clothes.
  2. Divide your hair into sections.
  3. Prepare your bleach powder and developer.
  4. Apply from middle to the tips.
  5. Leave the bleach in the hair for about 15 to 30 minutes depending on how light you want it.
  6. Cover with a shower cap or bag.
  7. Wash and condition your hair.

Remember to set a timer and by following the above tips, you will get the exact shade of hair you want every time.