How to Dilute Hydrogen Peroxide

Odds are high that you might already have hydrogen peroxide or H2O2 in your kitchen. It is one of the most popular disinfectants. Hydrogen peroxide is also used in beauty and health purposes including bleaching hair, mouthwash, treating acne, disinfecting small wounds and for many other medicinal purposes.

It comes in different concentrations. Hydrogen peroxide available at drug stores is generally 3% concentration. This generally recommended concentration for many medicinal uses. You will have to dilute hydrogen peroxide before its use if it is higher concentration than required for your intended specific use.

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What is Hydrogen Peroxide Good for and Why do You Need to Dilute it?

Hydrogen Peroxide is a chemical compound with a formula H2O2. It is easily mixable with water with formula H2O.

It comes in different concentrations. You will generally get it at 3% concentration at drug stores in a brown bottle.

3% or less is generally used for disinfectant, cosmetic and medicinal purposes. A 6% concentration is used for removing stains.

Most online stores will not sell more than 12% concentrated hydrogen peroxide as higher than 12% is considered a hazardous chemical in shipping. It requires special handling.


You can sometimes get 35% concentrated hydrogen peroxide at your nearest grocery store. First of all you will need to dilute and use it. Second, it is dangerous to handle. It can even cause death. The only advantage of high concentration is that it will take less storage space. But for household purposes the trade off is not worth considering the dangers.

Higher than 50% are used for Industrial purposes such as rocket fuel which requires special handling.

Our focus in this article is use of hydrogen peroxide for cosmetic and medicinal purposes.

Sometimes the Cosmetic and beauty industry uses different nomenclatures for the concentration of hydrogen peroxide. For example V10 is 3% and V40 is 12%.

Sometimes it is sold as parts per million or ppm as a unit for very specific requirements.

How to Dilute Hydrogen Peroxide?

When we consider diluting hydrogen peroxide it is always diluted with water.

Depending on the application you can dilute it in different proportions of water.

Diluting hydrogen peroxide is simple mathematics.

For example if you want to dilute 6% hydrogen peroxide to 3% then simply add equal amount of distilled water.

In a 100ml of 6% hydrogen peroxide there is 6 ml of H2O2 and 94 ml of water.

When you add an equal amount of 100 ml water, then the water has become 194ml and hydrogen peroxide remains 6ml but the total volume is 200 ml. So 6 ml in 200 ml is exactly like 3 ml in 100 ml.

1. Dilute to 3% Hydrogen Peroxide for Disinfecting Small Wound

  • Dilute it in equal amount of water if you have 6% H2O2 in your stock
  • If you have 3% in stock then no need to dilute
  • Clean the wound with 3% solution and cotton swab

2. Dilute to 1.5 % for Mouthwash

  • Take 1 teaspoon of 3% hydrogen peroxide in a small bowel
  • Add 1 teaspoon of water and mix well to make mouthwash
  • Gargle
  • Do it 2-3 times one after the other at the sametime.


3. Dilute Lower for Hair Lightening

Lightening of hair has many variables. How dark is your hair and how light you want are the two main variables. Start with lower concentration first to reduce the risk of making them too light and prevent damage.

Depending on whether you want to lighten hair for highlighting or completely change to lighter looks, use it as under.

  • Wash your hair with mild shampoo
  • Apply conditioner as you generally do and rinse
  • Dry your hair with towel
  • Wait for 30 minutes to completely dry hair
  • Take 1 part if 3% hydrogen peroxide and 2 parts of water to make it approximately 1% dilute
  • Apply on hair strands by strand
  • Leave it for about 30 minutes before rinsing
  • Wash your hair thoroughly and apply conditioner
  • Rinse and allow your hair to dry naturally

Other Uses of Hydrogen Peroxide

  • Clear up acne
  • Disinfect small wounds
  • Antiseptic mouth rinse
  • Bleach your hair or just add highlights
  • Whiten your nails
  • Whitening tooth
  • Remove ear wax
  • Prevent ear infection during swimming
  • Heal boils
  • Soften corns & calluses

Tips and Precautions

A 3% or lower hydrogen peroxide is generally safe. However take the following precautions during storage and use

  • Keep it labeled with % dilution data to avoid confusion
  • Can give sore throat, nausea, vomiting and abdominal pain if ingested in higher concentration or large quantities of diluted hydrogen peroxide
  • Gives eye strain, redness and blurred vision if exposed to eyes
  • Consult your doctor if you want to ingest hydrogen peroxide for any illness
  • Store it in dark container and away from light otherwise it will breakdown fast.
  • Keep it in the freezer for longer shelf life

Always use the right dilution ratio for every specific use to get the best results from hydrogen peroxide.