Ozone output explained: mg/h, g/h and what size room you can treat

Ozone generator listings show output in mg/h or g/h, and coverage claims in square feet or square meters. The numbers sound precise, but they are usually rough. This guide shows how to read them and how to estimate what you need.

Use the calculator on the home page for a quick estimate, then follow the manual of the unit you buy.

mg/h vs g/h

mg/h means milligrams of ozone produced per hour. g/h means grams per hour. One gram is 1,000 milligrams, so 3.5 g/h equals 3,500 mg/h and 10 g/h equals 10,000 mg/h.

When you compare listings, convert everything to the same unit first.

Why the number is only a claim

Output depends on the plate, the driver board, humidity, temperature and the age of the unit. Sellers often print the maximum measured under ideal conditions, and cheap units can fall well below it. No independent test is attached to most listings.

From output to room size

Calculate your room volume in cubic feet: length times width times ceiling height. A 12 by 12 foot room with 8-foot ceilings is 1,152 cubic feet. As a rough planning rule, listings tend to rate output around 0.3 to 0.5 mg/h per cubic foot for ordinary odors and about 1 mg/h per cubic foot for heavy ones.

That puts a 12 by 12 foot bedroom at roughly 500 to 1,200 mg/h, which most home units exceed. The timer then sets how much ozone the room gets.

Square feet claims

A listing that claims a unit covers 1,500 sq ft should be read as a maximum for light duty. Ceiling height, how sealed the room is and the odor level all change the real result.

Why bigger is not always better

A very powerful machine in a small room raises ozone levels quickly and takes longer to clear. For one room, a mid-range unit with a timer is easier to control. Save high-output machines for large empty spaces.