Free calculator

Grow room CO₂ calculator

Enrichment is two problems: the one-time charge to raise the room to setpoint, and the continuous top-up that replaces what leaks out with every air exchange. The leak usually costs more than the charge.

Room & setpoint

Result

Room volume 800 ft³ (22.7 m³)

CO₂ to raise room 4201,200 ppm
32g
= 0.07 lb of tank CO₂
Ongoing loss to air exchange
32g/h
≈ 1.7 lb/day held at setpoint
Time to setpoint at injector rate
-
Enter an injector rate to estimate this.
A 20 lb tank (9.1 kg) holds setpoint for roughly 11.7 days, plus another 32 g each time you vent and re-enrich.

Plants consume CO₂ too (roughly 20–50 g/h per kW of light at full canopy), so real usage runs above the leakage-only estimate. Never enrich an occupied sealed room without a monitor: 5,000 ppm is the workplace exposure limit.

Exhausting air you just enriched? Check your fan CFM →

How much CO2 do you need to enrich a grow room?

Calculate grams of CO2 needed to raise your room from ambient (about 420 ppm) to a target like 1,200-1,500 ppm based on room volume, then account for ongoing loss to air exchange to size your injector's continuous output. Sealed rooms need far less CO2 per hour than vented ones, since every air exchange purges enrichment. Enter your room and target ppm above for grams needed and time-to-setpoint.