Ozone Formulas and Conversions

Accurate ozone calculations are essential for proper system design, performance verification, and safe operation. This technical reference compiles commonly used ozone output and concentration conversions.

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Fundamental Properties of Ozone

Understanding the nature of the “activated oxygen” molecule is the first step in any ozone application.
Chemical Formula O3
Molecular Weight 48 g/mol
Gas Density at STP 2.14 kg/m3
Solubility in Water ~13x higher than Oxygen
Oxidation Potential 2.07 V

Common Ozone Measurement Units

Ozone is measured differently depending on whether it is in a gas or liquid phase.

Concentration Units (Gas & Liquid)

mg/L Milligrams per Liter Used for dissolved ozone in water.
g/m3 Grams per Cubic Meter The standard for measuring ozone concentration in a gas stream.
PPM Parts Per Million
  • 1 ppm is approximately 1 mg/L.
  • In air: 1 ppm by volume is 2.14 mg/m3.
% Weight Common for generator specifications.

  • 1% by weight in Air = 12.8 g/m3
  • 1% by weight in Oxygen = 14.3 g/m3

Flow Rate Units

LPM Liters Per Minute Standard metric for gas flow (oxygen or air).
SCFH Standard Cubic Feet per Hour Standard imperial unit for gas flow.
m3/hr Cubic Meters per Hour Used for high-volume gas or water flow.
GPM Gallons Per Minute Standard imperial unit for water flow.

Production & Pressure Units

g/hr Grams per Hour The standard measure of ozone generator output capacity.
lbs/day Pounds per Day Common in large-scale industrial ozone specs.
psi Pounds per Square Inch Measure of back-pressure on the system.

Key Formulas & Conversions

Ozone Generator Output

Estimates generator output based on feed gas flow and concentration
Output (g/hr) = (Flow (LPM) × 60 × Dosage (g/m3)) ÷ 1000
Capacity is expressed as mass produced per unit time. Essential for equipment sizing and comparison.
1 g/hr = 24 g/day
1 lb/day = 18.9 g/hr
1 kg/hr = 2.2046 lb/hr
1 mg/hr = 0.001 g/hr

Ozone Dosage Rate

This tells you how big your ozone generator needs to be to treat a specific flow of water at a specific target level.
Required O3 (g/hr) = (Flow (GPM) × 3.785 × 60 × Dosage (PPM)) ÷ 1000

Ozone Concentration

The conversion changes based on whether you are feeding the generator with Air or Pure Oxygen because oxygen is heavier.

Ozone Concentration in Air by Weight

100 g/m3 = 7.8% O3
1% = 12.8 g/m3 O3
 1% = 7284 ppm O3

Ozone Concentration in Air by Weight

 100 g/m3 = 6.99% O3
1% = 14.3 g/m3 O3
1% = 6520 ppm O3

Ozone Concentration in Air by Volume

1 mg/L = 1 g/m3 = 1 µg/mL = 467 ppm O3
1 ppm = 2.14 mg/m3 O3
100 pphm = 1 ppm

Ozone Concentration in Water

 1 mg/L = 1ppm = 1 g/m3 O3 (by weight)

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