Ventilation Calculator — Greenhouse Vent Requirements
Work out ventilation requirements for greenhouses and polytunnels.
How We Calculate This
The recommended vent area is 20% of the greenhouse floor area. This is a standard horticultural guideline for adequate air exchange.
Each standard greenhouse vent opening is approximately 0.4 m². The total vents needed = Required vent area / 0.4 m² per vent.
Volume is calculated as Length x Width x Height to give context for the air space being ventilated.
Frequently Asked Questions
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Last updated: February 2026
All calculations are estimates based on standard gardening guidelines. Results may vary with soil conditions, climate, and plant varieties.