CO₂ Enrichment Calculator

CO₂ injection rate, tank consumption, generator vs tank economics, yield response by crop. Plus safety thresholds.

Calculate CO₂ needs

Greenhouse length (ft)

Width (ft)

Height (ft)

Target CO₂ (ppm) 800 ppm — light enrichment 1,000 ppm — typical 1,200 ppm — peak benefit 1,500 ppm — diminishing returns

CO₂ source Compressed CO₂ tank (50 lb / 100 lb / bulk) Propane CO₂ generator (combustion) Natural gas CO₂ generator Compost / mushroom by-product (passive) Dry ice (small / hobby)

Air changes per hour (leakage) 0.5 ACH — sealed 1 ACH — modern greenhouse 2 ACH — typical poly 4 ACH — leaky / older Higher = more CO₂ needed to maintain

Daily injection hours Daylight hours; CO₂ only when photosynthesizing

CO₂ enrichment basics

CO₂ level	Effect
~420 ppm (atmospheric)	Standard outdoor; growth-limiting in sealed greenhouse
700-900 ppm	Modest improvement (5-15% yield)
900-1,200 ppm	Sweet spot — 15-30% yield increase typical
1,200-1,500 ppm	Diminishing returns; 25-35% increase max
1,500-2,000 ppm	Marginal additional benefit; cost rarely justified
> 2,000 ppm	Plant damage in some species; not economically beneficial
> 5,000 ppm	⚠ Worker safety threshold (OSHA TWA)
> 30,000 ppm	⚠ Acutely dangerous to humans

Source comparison

Source	Cost	Pros	Cons
Compressed CO₂ tank	$0.10-0.30 per lb CO₂	Pure CO₂; no heat; simple	Tank delivery logistics; ongoing supply
Propane (LP) generator	$0.05-0.10 per lb CO₂ produced	Cheap; produces heat (winter benefit)	Heat AND humidity by-products; can overheat in summer; combustion contaminants
Natural gas generator	$0.04-0.08 per lb CO₂	Cheapest if natural gas available	Same as propane — heat + humidity
Compost / mushroom	~free	No equipment; biological; passive	Inconsistent levels; inadequate for full enrichment alone
Dry ice	~$1-2 per lb (very expensive)	Simple; portable	Logistics; cooling effect
Wood-burning stove	Variable	Multi-purpose heat + CO₂	Fire risk; particulate emissions; needs scrubbing

Critical: safety

Concentration	Effect on humans
1,000 ppm	Normal indoor; slight stuffiness possible
1,500 ppm	Drowsiness; mild headache after hours
2,500 ppm	Concentration impaired; OSHA upper recommendation
5,000 ppm	OSHA TWA limit (8-hour exposure max)
10,000 ppm	Headache, dizziness, fatigue within hours
30,000 ppm	Difficulty breathing; heart palpitations
40,000 ppm (4%)	Immediately Dangerous to Life and Health (OSHA IDLH)
100,000 ppm (10%)	Loss of consciousness in minutes; potentially fatal

Mandatory: CO₂ alarms (set at 5,000 ppm); ventilation before entry; combustion CO + CO₂ alarms if using generator (CO is more dangerous than CO₂).

Yield response by crop

Crop	Typical yield increase	Notes
Tomato	15-25%	Well-documented; commercial standard
Cucumber	20-30%	One of best responders
Pepper	15-25%	Similar to tomato
Lettuce	10-20%	Less than fruiting crops
Cannabis flower	15-30% (controversial; depends on light + nutrient sufficiency)	Most beneficial under high-light conditions
Strawberry	10-20%	Variable
Roses, ornamentals	10-25%	Standard for cut-flower production
Microgreens	10-20%	Marginal due to short cycle

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