How Long Do You Leave Bleach in Your Hair?

How Long Do You Leave Bleach in Your Hair?

Sooner or later, most of us tend to let curiosity get the best of us, and we experiment with hair dye. It’s all fun and games until you want to go lighter. Going blonde IS fun, but you have to do it right.

That being said, I’m not going to beat a dead horse here. I’ve told you guys before that when it comes to bleaching, especially if you have really dark hair, you should have it done by a colorist to keep from damaging it.

Ah, but we’ve all been there. I know I have. So, if you’re determined to bleach your own hair, then I hope you’ll read all my other posts so you can minimize damage and do it right.

Every box of hair bleach has general instructions on it, but see, the thing is, the box doesn’t know you.

Your stylist knows you. They can look at your hair type. Is it fine? Is it coarse? Is it super-dark? All these things come into play when determining how long to leave bleach in your hair.

So, you’re probably asking yourself, how long do you leave bleach in your hair? Well, keep reading to find out.

How Long Do You Leave Bleach in Your Hair?

Bleach gets activated with heat, but once it starts to dry, which is usually after 45 minutes it gets deactivated. So, leaving it on for longer than that won’t do anything more in terms of lifting color.

Generally, you should leave bleach in your hair for no more than 20 minutes, but how long you need to leave bleach in your hair depends on a number of factors, including your hair color and type.

If you have very dark hair, then you should leave the bleach in for up to 30 minutes. If you have very light hair, then 10 minutes is usually enough.

However, it’s always best to consult with a professional before bleach your hair at home. They will be able to give you specific instructions on how long to leave the bleach in, as well as what type of bleach to use.

It’s more than just your type of hair and its current color. It’s also how bright you want that blonde to be. And if you’re expecting to go from dark to platinum in one go, nope!

Go read my post about what to consider before bleaching your hair if you don’t want to give yourself an orange clown-haired look!

You should never leave bleach on too long. You have to plan this accordingly, especially when using developer at volumes of 20 or 30.

If not, you’ll have damage, and your hair will come out an unfavorable shade than you planned, whether orange (if your current strands are dark brown or black) or even too light (if you already had a lighter brown or darker blonde shade).

The best way to keep from bringing yourself to tears and stapling a hat to your head is to do a teensy little strand test. This will help you get the best timing for bleaching on your own head of hair.

Always follow the instructions in your bleaching kit and never go longer than what it recommends. Again, that’s usually going to be anywhere from 15 to 30 minutes, but I’ll cover this in much greater detail further on, so follow me!

4 Factors to consider before bleaching your hair

Factor 1: Your hair color

Factors to consider before bleaching your hair Factor 1 Your hair color

The first thing you need to consider here is your current hair color. The darker your hair, the longer you need to leave the bleach in. That will also result in greater damage, so it’s wise to be realistic about the shade you want to go.

You might find lightening it a few shades every month is a better way to achieve your blonde ambitions. For hair that is already light or that has been bleached before, you won’t have to leave bleach in your hair for very long.

Factor 2: The color you’re aiming for

Factors to consider before bleaching your hair Factor 2 The color you’re aiming for

Now, let’s talk about those hair goals. What shade do you want to see? If you’re only going to lighten a few shades, you’ll only need to leave the bleach on a short while.

This will also be less damaging. And if you want something more dramatic, you’re going to need it to stay on longer. This allows the bleach to lift out the pigments in your hair shaft to lighten it up.

Factor 3: Your hair type

Factors to consider before bleaching your hair Factor 3 Your hair type

If you have never before colored your hair much less dyed it, it’s virginal. And you need to be extra gentle with it, or you’ll lose that luscious luster.

Virgin hair lightens up more quickly, so you should really keep tabs on the time. And honestly, if this is your first time bleaching and your hair is dark, I can’t stress it enough that you will thank me later if you go to a colorist.

Factor 4: The type of developer you’re using

Factors to consider before bleaching your hair Factor 4 The type of developer you’re using

First-time dyers and bleachers tend to go with the kits. They provide everything you need in one box that makes it easy to mix the developer with the bleach.

It also tells you how long to do it. You can buy these things separately, but if you don’t know a thing about color, bleach, or developer, a box is a better way to go to avoid buying the wrong shade.

At the salon, your colorist mixes these things together and leaves it on for a specified amount of time-based on your current color, your hair type, the shade you desire, and the condition of your hair.

In general, for those that will leave the hair bleach on for longer, a lower volume of developer will be used to minimize damage.

How to know when it’s time to remove bleach

How do you know it’s time to remove the bleach

Never just wing it when it comes to bleaching. You should set a timer and make sure you’re looking at your hair every so often while it’s lifting so you can see whether or not you need more time.

You don’t want to come back 30 minutes later and have your jaw smash into the floor. Again, a strand test can really help you see how things are going to turn out and how long you should let the bleach sit.

Here’s how to perform a strand test:

  • Mix up just a little bit of bleach mixture.
  • Take the bleach mixture and dab it on just the ends of a few strands on the underside of your head.
  • Check every couple of minutes while keeping time.
  • Once you get to a shade you like, that is the magic time to set for your whole head!

I recommend just a few ends on the underside of your head because if you hate it, you can snip those off, and no one will ever see it. But if you love it, then you will be ready to go for the whole bleaching session.

It’s not mandatory to do the strand test, but if you’ve never bleached before, I think you should do it, or else you might wind up with a color you didn’t bargain for.

Like what, you may ask? Oh, sweetie, keep reading!

What happens if you leave bleach in your hair for too long?

You do not, I repeat, DO NOT want to leave the bleach on your hair too long. There are a number of reasons you should avoid this at all costs:

  • Damage! Bleach is a damaging process. If you let it outstay its welcome, you’re going to do horrible things to your hair that will make you cry. Follow the directions and don’t overdo it. If you want to go lighter than the results you get (remember, aim for 2 shades lighter when going from dark and work your way down to the blonde you want over time), you need to wait about 14 days at minimum before giving it another go.
  • Too light! If you didn’t want platinum blonde, you will be in for a shock if you leave bleach on too long. And remember, damage!
  • Orange! This is even worse than just damage. Because your hair will be damaged AND orange. I wrote a detailed article on how to fix orange hair after bleaching, so spare yourself the trauma and follow the rules.

Also, you should know that bleach stops doing its thing after some time. Once it starts drying, it stops processing, and you won’t get any lighter.

Instead, you’re just damaging until it dries up and then making your hair into the texture of hay rather than having that sexy California beach blonde hair you wanted.

What to do if you left bleach in your hair for too long

What to do if you left bleach in your hair for too long

I once had a friend who tried to bleach her hair on her own, then got into a massive blowout with her horrible boyfriend on the phone. After 45 minutes, she realized she’d left the bleach on too long. It was a disaster.

Please, if you’re going to do this, pay attention. But if you’re reading this in a panic because you accidentally zoned out while binge-watching Netflix or got lost in the pages of a book, here’s what you can do to remedy the situation:

  • No shampoo! Just for a day or 2. Your hair is already dried out from the bleach, and you need to let those natural oils from your sebum build-up. You CAN condition it though, so go for it.
  • Go intensive! A deep hair conditioning treatment such as a cream mask or hair oil done every other wash prior to shampooing can do wonders. You can also sleep on it though wrap your hair gently, so you don’t suffer breakage and keep it from getting all over your pillow. Rinse it and style it in the morning.
  • Leave-in love! A leave-in conditioner is ideal daily to keep your hair hydrated. It will also keep it from looking like a frizzed up, dried-out witch’s hairdo too.
  • Stock up on protein masks! You should use them for the week after you bleach your hair. The more brittle it is, the more often you should do this. You can even use an egg with a spoonful of yogurt to make a protein mask. Or buy one like Moroccanoil Restorative Hair Mask. Whichever you do, leave it in for 30 minutes and cold-water rinse.
  • Don’t brush wet hair! This is a cardinal sin in hair care, even if you didn’t bomb your hair out with bleach. Instead, use a microfiber towel, or in the absence of that, an old soft t-shirt to gently wrap it and let it dry naturally.
  • Supplement! Healthy hair also begins inside, so start taking the right supplements to nourish from within. Fish oil capsules are great, but if you’re vegetarian or vegan, or you don’t want to burp fish stink all day, use flaxseed oil.

You’re likely to notice a bit of damage at the ends, so it’s wise to get a cut to get rid of it before it becomes worse. Go to your stylist ASAP and have that done professionally, especially if your hair is breaking mid-length.

And if lobbing off all your hair sounds like the kiss of death (it is), you can always get a quarter of an inch trimmed each month, which will slowly but surely get rid of the damage.

Don’t forget to minimize sun exposure, watch out for heat styling tools, and simply let your hair get healthy again, or you will make things even worse.

Common mistakes when bleaching your hair at home

There’s a reason why professional colorists insist you not bleach on your own. Bleaching requires a tender touch and a lot of know-how, something they all were trained for professionally.

Again, please see your stylist, but if you’re not going to listen to me, at least look at these mega-mistakes that people most commonly make when bleaching at home so you can avoid them.

– Not being prepared and ready

Common mistakes when bleaching your hair at home Not being prepared and ready

Have you ever tried to cook a recipe and you don’t have what you need all gathered around? It’s like chasing a headless chicken around your kitchen.

The same goes for bleaching your hair. You want to make sure you have everything there ready to go. If not, you’ll wind up having to run to the store or even worse, wing it, because you forgot something.

– Ignoring instructions

Common mistakes when bleaching your hair at home Ignoring instructions

I always read the instructions for hair color and bleach, and you should too. I do it every time, even though I’ve read them countless times.

This ensures you don’t forget something. I almost forgot to add developer one time because I was distracted. That would have been a huge mistake!

– Skipping strand testing

Common mistakes when bleaching your hair at home Skipping strand testing

Unless you have bleached your hair before and know exactly how long it takes to get to your desired shade of blonde, don’t skip the strand test.

And even if you have bleached before, it’s easy to get haughty about it and not realize that what worked when you were a darker shade of blonde might be too much now. Just check yourself first!

– Doing it alone

Common mistakes when bleaching your hair at home Doing it alone

I had one friend that attempted to bleach her hair by herself and missed a bunch of places on the back of her head.

The result was very spotty and rather embarrassing. If only she’d waited until her roommate was home first, she would have pointed it out and saved her the embarrassment.

– Leaving bleach on too long

Common mistakes when bleaching your hair at home Skipping strand testing

Again, the 15 to 30-minute time bracket I gave at the beginning is all contingent upon different factors that I laid out earlier. Don’t leave it in too long. Just don’t. You will come to regret it.

– Forgoing deep conditioning prior to bleaching

Common mistakes when bleaching your hair at home Forgoing deep conditioning prior to bleaching

If you’re really set on bleaching your hair at home or even if you plan on getting it done professionally, deep conditioning in the weeks leading up to the bleaching can work wonders.

It will keep your hair strong and minimize the damage. You can also use coconut oil. I’ve got a whole post devoted to how long you have to leave coconut oil in your hair before bleaching.

– Not paying attention to texture and condition

Common mistakes when bleaching your hair at home Not paying attention to texture and condition

So, you bleached your hair, and it didn’t arrive at the shade you wanted quite yet. You may want to bleach it again, but you should look over your hair first. If it feels brittle or breaks off, not a good idea to do more bleaching.

Consulting with a professional can give you a better timeline of when you can get back to it, but in the meantime, get busy on deep conditioning.

– Over-styling your hair after bleaching

Common mistakes when bleaching your hair at home Over-styling your hair after bleaching

If you pushed your hair to the brink with bleaching, you’re not doing it any favors by cooking it in high heat.

Even with heat protection spray (which you should ALWAYS use no matter what kind of hair you have), you can ruin your hair.

– Doing your whole head instead of just the roots

Common mistakes when bleaching your hair at home Doing your whole head instead of just the roots

Now let’s say you’ve bleached your hair already with some success, or you went to a pro. But now, those roots! Whatever you do, just touch up the roots and don’t apply bleach to your whole head.

– Not using toner

Common mistakes when bleaching your hair at home Not using toner

When you wind up with brassy hair, you need to use toner. If it’s orange, it needs to be bleached a little longer. Never skip toner and go for another bleaching.

Again, I cover orange hair problems after bleaching in another post. As for toner, it adds color back in after it was stripped away. It won’t lift your hair shade though.

You also need to use the right toner. Purple should be used very lightly as it can stain your bleached hair and leave you with purple hair. Unless you want purple hair as the final outcome, don’t!

You can also use ammonia-based toners, but they are mixed with developers and tend to be way harsh. One of the best options is purple shampoo because it keeps your cool tones and is very gentle.


You never should leave bleach on for longer than any bleach kit recommends. Always test out a strand to see how long it will take for your hair because we’re all different.

My hair could take 20 minutes to get to that perfect shade of blonde, but it might only take you 15. Five minutes doesn’t seem very long, but when you’re bleaching, things can escalate very quickly.

Take care of your hair and follow the instructions so you’ll wind up with fabulous hair rather than hair that makes you cry!


My name is Hajer and welcome to my site. This is my little haven, my outlet, where I can express myself, and show you everything I've learned about makeup, skincare, hair tips, and so much more, as well as the different beauty mistakes I've made so that you can avoid them.

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