How It Works
This calculator works in 4 steps.
Enter the stock percent
Type the H₂O₂ percent on the label, such as 35%.
Enter the target percent
Type the specified working strength, such as 3%.
Enter the final volume
Type the volume in mL, L, or US fl oz.
Read the amounts
The calculator returns peroxide volume, water volume, and the parts ratio.
The Formula
The formula applies C₁V₁ = C₂V₂ and reports the water parts per peroxide part.
V₁ = C₂ × V₂ / C₁X = C₁ / C₂ − 1V_water = V₂ − V₁- C₁ / C₂:
- Stock and target percent
- V₂:
- Final volume
- X:
- Water parts in a 1:X mix
1 L of 3% from 35% stock needs 85.7 mL peroxide and 914.3 mL water, a 1:10.67 ratio.
Conversion Table
The conversion table gives peroxide and water per 1 L (33.8 US fl oz) for 6 dilutions.
| Stock | Target | Ratio (H₂O₂:water) | Peroxide per 1 L | Water per 1 L |
|---|---|---|---|---|
| 35% | 3% | 1:10.7 | 85.71 mL | 914.3 mL |
| 35% | 6% | 1:4.83 | 171.4 mL | 828.6 mL |
| 12% | 3% | 1:3 | 250 mL | 750 mL |
| 6% | 3% | 1:1 | 500 mL | 500 mL |
| 3% | 0.5% | 1:5 | 166.7 mL | 833.3 mL |
| 50% | 3% | 1:15.7 | 60 mL | 940 mL |
What Is the Hydrogen Peroxide Dilution Calculator?
The Hydrogen Peroxide Dilution Calculator is a tool that dilutes a hydrogen peroxide (H₂O₂) stock to a specified target percent and returns the peroxide and water amounts. 35% H₂O₂ diluted to 3% needs 1 part peroxide to 10.67 parts water.
Concentrated hydrogen peroxide at 30% to 35% is a strong oxidizer that burns skin and reacts with organic material. The calculator lists the target only as the user specifies it and prints the handling note: wear gloves and eye protection, add peroxide to water, and store in a vented, opaque container. Values use % w/w labels with water-like density, which is close for 3% to 12% products.
Common Uses
There are 5 main uses of this calculator.
Surface cleaning
Users dilute concentrate to labeled cleaning strength.
Lab reagents
Labs prepare 3% H₂O₂ for catalase tests.
Hydroponics
Growers dilute peroxide for system cleaning per product directions.
Aquarium care
Hobbyists dose diluted peroxide per product guidance.
Laundry
Users dilute peroxide for stain treatment.