How Long To Leave Bleach In Hair? Here's The Answer 2023 (2023)

As summer kicks off, many of us are looking for ways to get a lighter, sun-kissed glow in our hair. But figuring out how long to keep a bleaching solution on without damaging your hair can be tricky. Striking that perfect balance between blonde hair and maintaining hair health is key.

Read on to learn how long to leave bleach in hair and ways to deep condition hair after bleaching. Perfecting your bleaching time can help you get your dream summer hair while keeping your locks happy and healthy.

How Long Should You Leave Bleach On Your Hair?

The amount of time you leave bleach on your hair depends on many factors, such as:

  • Current hair color.
  • Desired level of blonde.
  • Bleach product used.

While the processing time generally ranges from 20 to 45 minutes, closely monitoring color development during bleaching is crucial. Leaving bleach on for too long can lead to over-processed and damaged hair.

What Is Hair Bleach?

Hair bleach is a chemical product[1] designed to lighten your natural hair color. It typically has ingredients that break down melanin,[2] or the color particles, inside the strand of hair. The most common bleaching ingredients are:

  • Hydrogen peroxide.
  • Ammonia.
  • Persulfates.

Hair bleach can be used for techniques like highlights or full-head bleaching. It comes in powder or cream forms that can be applied by a professional hairstylist or at home.

How To Know When It Is Time To Remove Bleach

Maybe you are asking yourself, how long should I leave bleach in my hair? Luckily, here are a few things that can help you learn the ideal bleaching time for your hair.

Color Development

How Long To Leave Bleach In Hair? Here's The Answer 2023 (1)

Monitoring your color development during bleaching is vital to get the best results and avoid mishaps. As the bleach works its magic, the color will progress through various stages. Try checking your hair at least every 10 minutes so you know when to stop.

Hair Condition

How Long To Leave Bleach In Hair? Here's The Answer 2023 (2)

Regularly checking the hair’s condition helps determine the optimal timing for bleach removal. During the bleaching process, excessive dryness, brittleness, or breakage can occur. Quickly remove bleach if any signs of adverse reactions happen.

Factors That Affect Bleaching Stages

Several factors can influence the stages of hair bleaching:

Natural Hair Color

Your natural hair color helps determine how many bleaching stages are needed to get the blonde level you want.

Bleaching removes the natural melanin in the hair strands, which takes more time and effort for dark hair. But people with lighter hair colors, such as blonde or golden brown, may need fewer bleaching stages for the desired level of lightness.

Hair Type And Texture

Hair type and texture significantly impact bleaching stages in the hair-lightening process.

  • Fine or thin hair may bleach more quickly than coarse or thick hair. Thinner hair strands are smaller in diameter with fewer cuticle layers[3] allowing the bleach to penetrate easier. This results in faster color change.
  • Coarse or thick hair may require more time and multiple bleaching stages to achieve the desired lightness. The density and texture of the hair may affect how evenly the bleach spreads, requiring additional care and attention to avoid patchiness or uneven color.
  • Curly or tightly coiled hair may have more resistance to the bleaching process due to the structure of the hair strands, requiring longer processing times or more potent bleaching formulations.

Bleach Strength And Developer Volume

The bleach’s strength and the developer’s volume impact the stages of the bleaching process.

Bleach strength is the potency of the bleach, while the developer volume indicates the concentration of hydrogen peroxide solution. Volume 10, 20, or 30 developers are commonly used to lighten hair shades. The higher numbers are used to lighten dark brown or black hair.

Stronger products can increase the risk to your hair. To determine how long to leave volume 30 bleach on hair, check the progress every 5-10 minutes. Limiting the bleaching time to 30 minutes may help reduce risks and save your lovely locks.

Application Technique

The application technique can impact the stages and overall outcome, resulting in different color lift and distribution degrees.

For example, applying bleach with foils or using a highlighting technique can create dimension with lighter strands while maintaining a natural look. On the other hand, evenly applying bleach all over the hair can lead to an overall blonde and more consistent result.

Proper application technique, careful monitoring, and timing are a dynamic trio to help prevent damage while lightening your locks.

Hair Condition And Health

Healthy, well-maintained hair responds better to bleach and withstands processing times with little damage. Damaged hair is more susceptible to over-processing, leading to breakage, brittleness, and uneven color results.

It’s important to assess the condition of your hair before bleaching and take necessary precautions. A deep conditioning treatment or another product to repair hair health can help improve and restore hair before bleaching.

Professional Bleaching

While DIY options may be tempting, seeking the help of hair professionals has its benefits too. Many salons offer a bleach bath that can reduce the steps and time needed to lighten hair. A bleach bath may not lighten hair as much as other bleaching techniques but can give your hair a slight, sun-kissed look. A hair stylist can evaluate your hair type and decide how long to leave a bleach bath on your hair.

What Happens If You Leave The Bleach On For Too Long?

Leaving bleach on your hair for too long can severely damage your hair. As bleach breaks down the hair’s natural pigment,[4] these things can occur:

  • The hair cuticle becomes more porous and spongelike.
  • The hair shaft becomes swollen.
  • There is increased brittleness due to porosity and swelling.

Over-bleached hair can appear dry, frizzy, less shiny, or patchy in color.

Common Mistakes To Avoid When Bleaching Hair At Home

When bleaching your hair at home, it’s important to avoid these common mistakes:

  • Not conducting a patch test[5] — a hair dye or bleach mixture may cause an allergic reaction, so a patch test is necessary.
  • Incorrectly measuring and mixing bleach — proper measuring and mixing can help get the blonde you want without ruining your hair.
  • Overlapping the bleach — applying bleach on previously treated hair can result in over-processing. Avoid overlapping the bleach onto already lightened sections, and focus on new growth instead.
  • Using the wrong developer strength — different hair types and desired results require specific developer strengths. Too strong of a developer can lead to excessive damage, while a weak developer may not give sufficient lift.
  • Neglecting hair conditioning and aftercare — bleaching can dry out and damage your hair. After bleaching, use a deep conditioning treatment or a nourishing hair mask to help restore moisture.

Ways To Take Care Of Your Hair Post-Bleaching

Proper hair care after bleaching is a must for stronger, healthier, more vibrant hair. Here are some essential tips for caring for your hair after bleaching:

  • Moisturize and hydrate — bleaching can strip the hair of its natural moisture, so deep conditioning treatment or using a hair mask weekly can be helpful to restore moisture and nourish your hair.
  • Minimize heat styling — use blow dryers, curling irons, and flat irons as little as possible, and protect hair with a heat protectant spray.
  • Avoid harsh chemicals — after bleaching, avoid chemical treatments, such as perming, relaxing, or coloring, to allow your hair time to recover and regain strength.
  • Protect from the sun — UV rays can damage bleached hair and cause color fading. Avoid extra damage by wearing a hat or using UV-protective hair products.
  • Use gentle hair care products — choose sulfate-free shampoos and conditioners specially designed for color-treated or damaged hair.
  • Consider adding collagen — a collagen supplement can help support[6] healthy hair, especially after damage caused by bleaching.

Remember, everyone’s hair is unique, so take some time to understand your hair’s needs. Consistent and gentle hair care practices will help strengthen your hair and maintain your beautiful locks.


Answering the burning question of how long do you leave bleach in your hair comes down to meeting your hair’s specific needs. Hair type, color, and condition help determine how long bleach should stay on your hair.

Bleaching comes with risks, like drying out your hair or ruining your color. Luckily, you can follow our tips to minimize any damage. Combining knowledge, proper techniques, and regular hair care lets you enjoy the benefits of hair bleaching while keeping your locks luscious and healthy.

+ 6 sources

Health Canal avoids using tertiary references. We have strict sourcing guidelines and rely on peer-reviewed studies, academic researches from medical associations and institutions. To ensure the accuracy of articles in Health Canal, you can read more about the editorial processhere

  1. Guerra-Tapia, A. and E. Gonzalez-Guerra (2014). Cosméticos capilares: tintes. [online] 105(9), pp.833–839. doi:
  2. Mostert, A.B. (2021). Melanin, the What, the Why and the How: An Introductory Review for Materials Scientists Interested in Flexible and Versatile Polymers. [online] 13(10), pp.1670–1670. doi:
  3. Baltenneck, F., Genty, G., Elias Bou Samra, Richena, M., Harland, D.P., Clerens, S., Leccia, E., M. Le Balch, Doucet, J., Michelet, J.-F. and Commo, S. (2022). Age-associated thin hair displays molecular, structural and mechanical characteristic changes. [online] 214(4), pp.107908–107908. doi:
  4. Guerra-Tapia, A. and E. Gonzalez-Guerra (2014). Hair Cosmetics: Dyes. [online] 105(9), pp.833–839. doi:
  5. Lee, H., Kim, W.-J., Jun Suk Kim, Kim, H.-S., Kim, B.-G., Kim, M.-B. and Ko, H.-C. (2016). Patch tests with commercial hair dye products in patients with allergic contact dermatitis to para-phenylenediamine. [online] doi:
  6. JDDonline – Journal of Drugs in Dermatology. (2022). A Six-Month, Randomized, Double-Blind, Placebo-Controlled Study Evaluating the Safety and Efficacy of a Nutraceutical Supplement for Promoting Hair Growth in Women With Self-Perceived Thinning Hair – JDDonline – Journal of Drugs in Dermatology. [online] Available at:


How Long To Leave Bleach In Hair? Here's The Answer 2023? ›

There's a misconception that bleach will work better the longer you leave it on. The maximum amount of time you should leave bleach on your hair is 30 minutes. Any longer than that and you run the risk of serious damage, including brittle strands.

How long do you leave bleach on roots? ›

It's important not to start at the scalp, as it processes quicker from body heat. Once the rest of the hair is done, go back and apply bleach to the roots. Let bleach process between 20-45 minutes, depending on your hair color, desired results, and package directions.

How long does 20 volume developer take? ›

Generally, a 20 volume developer can be left on for up to 30 minutes, but always read the instructions on the box and do a strand test beforehand to make sure that your hair can handle it.

How many levels does 20 volume developer lift with bleach? ›

When used with bleach, 20 volume is a powerful tool lifting 1-9 levels depending on the bleach, method of application, and hair type/history. 20 volume is the highest level of developer that should be used on the scalp with bleach as the scalp produces more heat and increases the power of the developer.

How long to leave bleach on black hair? ›

Wait for the bleach to work – Place a plastic bag over your hair and wait for around 40-60 minutes, while checking the colour once every 10 minutes. When bleaching black hair, you'll see your hair transition from its natural dark colour to orange, before finally turning light yellow.

How long do hairdressers leave bleach in? ›

How long do you need to leave bleach on hair to color it?
Hair color and textureHow long to leave on
blonde hair15 to 20 minutes
dark hair30 minutes; it's recommended you split the process into several sessions
fine hair10 to 15 minutes; this type of hair will process faster since it has a thinner cuticle layer
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Sep 21, 2020

What is the longest time to leave bleach on roots? ›

The hair at the roots, because of body heat from the scalp, lift quicker. Therefore, the roots take less time to bleach than the rest of the hair. Keeping it any longer than 20-25 minutes could damage the roots.

What happens when you put 30 volume developer in your hair? ›

The release of oxygen will indeed allow the hair to lighten. And 30 Vol will definitely do this to a greater extent than 20 Vol. But we don't recommend that you apply just developer to the hair. You will get an uncontrolled lift, without any re-coloration and you will end up damaging the hair.

Does 20 developer lift more than 30? ›

For up to 3 levels lift, use bleach with 20 Vol developer. For greater than 3 levels lift, use bleach with 30 Vol developer. For second time bleach applications, use only 20 Vol developer. Otherwise you will damage the hair excessively.

When should I start timing my hair bleach? ›

After your roots at the front are covered in bleach, paint the mixture on to the fine strands around your hairline. Once the front of your head is covered in bleach, set a timer for either 30 minutes or 45 minutes, depending on your hair shape, texture and the results of your strand test.

How long can you leave 20 vol bleach in? ›

For 20 and 30 Vol developer, the time taken can vary from 15 minutes up to 30 minutes. Please note, however, there is no fixed development time with bleach - you need to check every few minutes and rinse when the hair is lifted.

What happens if you use too much developer when bleaching hair? ›

If there's too much developer in your bleach mixture, it will be too runny. A runny product can drip and get everywhere, including your face and arms. Aside from the mess, this can also cause skin irritation.

What is the strongest hair developer? ›

40 Volume Developer / 12% Peroxide

This is the strongest volume that can lift your hair up to 7 levels. It is ideal for lightening or bleaching hair and requires experience in developer application techniques to handle it safely. It is also recommended to conduct a sensitivity test for such hair developers.

Which bleach is best for dark hair? ›

The award-winning Wella Blondor Multi Blonde Powder is a favourite with many hairdressers across the world. It provides controlled and reliable lightening of up to 7 levels, making it ideal for bleaching dark hair.

Do you shampoo after bleaching? ›

Avoid washing your hair for the first 48-72 hours after bleaching it. Give your hair ample time to seal in its new color. Because bleaching is such a volatile process, your cuticles remain open for longer immediately following a bleaching session.

Can you go platinum blonde in one day? ›

It probably won't happen in one sitting.

You'll pretty much have to carve out half a day to get your hair colored, thanks to the multiple steps required to get such a light shade, especially if you're starting with darker hair.

How long should I leave 20 developer bleach on my roots? ›

For 20 and 30 Vol developer, the time taken can vary from 15 minutes up to 30 minutes. Please note, however, there is no fixed development time with bleach - you need to check every few minutes and rinse when the hair is lifted.

Do roots bleach faster than ends? ›

Roots need less time than ends as the heat from the head speeds up the process,” explains Gallacher. “Once the hair has an even tone, the bleach is rinsed off and toned to the desired shade, but some hair will need more than one service to achieve the colour wanted.”

Can I use 30 vol on roots? ›

When applying 30 Vol, be aware that it will process very fast on the root area because of the heat coming from the scalp. In most cases it would be a good idea to apply 30 Vol to that area last. Or better still: use 20 Vol for that area.

Should I use 20 or 30 developer with bleach? ›

Developer Choice Going Lighter With Bleach

For up to 3 levels lift, use bleach with 20 Vol developer. For greater than 3 levels lift, use bleach with 30 Vol developer. For second time bleach applications, use only 20 Vol developer. Otherwise you will damage the hair excessively.


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