Hydrogen Peroxide Dilution Calculator

This hydrogen peroxide dilution calculator will work for diluting any concentration of hydrogen peroxide. A lot of the charts you’ll find online are only for diluting 35% peroxide down to 3%. That didn’t seem very useful since a lot of people are trying to convert different concentrations, such as 28% and 31%.

Use the calculator to dilute from any concentration, down to any concentration, and in any quantity. In the video below I show exactly how I use the dilution calculator to dilute 35% peroxide down to 6% for cleaning my hydroponic media. The video is set to start at the calculation.

Warning: Hydrogen peroxide in concentrations above 6% is caustic and can result in injury if it comes into contact with skin or eyes. Also, don’t swallow it….That would be bad.

How to the Use Calculator

Initial H2O2 Concentration: Enter the starting concentration here. Example: 35
Desired Dilution To: Enter the desired final dilution. Example: 3
Total Diluted Volume: Enter the desired total volume. Example: 3.8

There is no calculate button, the calculations will be performed automatically as you enter values.

Initial H2O2 Concentration Normal “Food-Grade” hydrogen peroxide concentration range from 28-35%.
Desired Dilution To For hydroponic gardering, the most common dilution is 3%.
Total Diluted Volume Enter the total volume (in Liters) of diluted H2O2 you want to produce.
Example: For 1 Gallon, enter 3.8
0% H2O2
0% H2O2 Solution
0 Liters
My Source for Hydrogen Peroxide
35% Food Grade Hydrogen Peroxide 1 Gallon

I get emails all the time asking where to buy 35% hydrogen peroxide. This is where I get it. It's excellent for hydroponic applications.

What I like:

  • Zero stabilizers - Zero additives - Fast shipping
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Common Volume Conversions

These conversions make it a easier to convert metric to U.S. standard volume. The values are close approximations.

1 Gal = 3.8 L1/2 Gal = 1.9 L1 Qt = .96 L1/2 Qt = .48 L
 1 Pt = .48 L1/2 Pt = .24 L 
Gal = Gallon | Qt = Quart | Pt = Pint | L = Liter

Why Metric Measurements?

Being from the United States of America, I totally get the preference for pints, quarts, gallons, etc. The problem with these measurements rears its head when you start breaking out the 1/4 cup, 1/2 cup, 3/4 cup, cup, tablespoon, teaspoon, and half teaspoon measurements. I'm not a fan of having a drawer full of measuring cups.

Premium Measuring Cylinder Set - 25ml, 50ml, & 100ml

I use this graduated cylinder set all the time for small measurements. They're well-marked and work great for diluting hydrogen peroxide and mixing nutrient solutions.

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02/18/2024 03:06 am GMT

Using metric volume makes dilution measurement really easy.

Example: 35% H2O2 diluted to 1 pint of 3% H2O2

(2 TBSP + 1TSP 35% H2O2)+(1 3/4 CUPS + 4 TSP Water) = 1 Pint 3% H2O2
(41ml 35% H2O2) + (439ml Water) = 480ml 3% H2O2 (approx. 1 Pint)

The simplicity of using metric measurements is why I chose to go that route with this calculator. Big box stores sell mixing cups (usually near the paint section) that have milliliter and liter markings. Personally, I buy 1 quart cups, 1 liter, and 3 liter buckets and have found them to be extremely useful for diluting liquids.

Common Uses of H2O2 in Hydroponics

Hydrogen peroxide is an effective tool for gardeners, especially hydroponic gardeners. Some of the most common uses in hydroponic gardening are:

When used as a nutrient additive in hydroponic systems, 30-45ml 3% H2O2 per gallon of nutrient solution should provide benefits without posing any risk to the plants. Always start with a low dose and increase slowly to ensure plant health.

Household Cleaning

Did you know that hydrogen peroxide is more effective than chlorine bleach at sanitizing and sterilizing porous surfaces?

Peroxide can be used as a household cleaner and sterilizer. Be careful using concentrations above 6% as it can damage surfaces. Hydrogen peroxide can oxidize metals, so keep that in mind as you clean.

Of course, if you’re wanting to make new metal look rusted and aged, hydrogen peroxide is the quick ticket to instantly-aged looking DIY projects.

Happy Diluting!

I hope you find this calculator helpful for diluting hydrogen peroxide. It’s one of the tools on this website that I return to frequently for my own use. If you like it, please share it!