Garden & outdoor
How much polytunnel or greenhouse cover film do you need?
Cover film m² and arch count for a garden polytunnel or small greenhouse from length, width and height — with spare for burial.
Quick answer
A garden polytunnel is a hoop frame plus clear film. The number that empties your wallet is cover area: length × the curved “developed” width of the hoop, plus end walls and a little extra to bury the edges so wind does not rip the sheet out. A 6 × 3 × 2 m hoop tunnel often needs on the order of 45–55 m² of film once ends and burial are included — more than the 18 m² floor footprint.
Advanced settings
Cover film needed
50 m²
- Floor footprint
- 18 m²
- Hoop arches
- 8
- ≈ meters of 4 m-wide roll
- 12.4 m
Related garden tools
Hoop cover ≈ length × (arc + 2×burial), plus two end panels, plus spare %. Arc uses a half-ellipse approximation — real kits vary. Use UV greenhouse film, tension clips, and anchor against wind. Not a structural engineering certificate for snow load.
How it works
The calculator approximates the hoop as a half-ellipse arc, adds two end panels, and a burial strip on both long sides. Arch count follows your spacing (0.5–1 m is common DIY). Buy UV-stabilized greenhouse film; cheap tarps cook plants and tear in a season. Pair with the vegetable-garden and irrigation calculators when you fill the tunnel.
The cover almost never fails in the middle. It fails where it rubs on the hoops: wind moves the film against bare metal thousands of times, and the metal gets hot in the sun, so the plastic thins and splits along the arcs first — wrapping each hoop with a strip of old hose, foam or purpose-made tape can add years to a cover for the price of an afternoon. The other thing to plan before buying film is ventilation: a closed tunnel in spring sunshine passes 45 °C easily, which cooks seedlings, so you want openings at both ends and not just a door.
Frequently asked questions
How much film for a 6×3 m polytunnel?+
With ~2 m height, burial and ends, plan roughly 45–55 m² of cover — check the calculator with your exact height. Floor area alone (18 m²) underestimates badly.
Polytunnel film vs greenhouse glass?+
Film + hoops is cheaper and DIY-friendly for vegetables; glass or polycarbonate greenhouses cost more but last longer and handle wind/snow better. This tool sizes film cover, not glazing bars.
How far apart should hoop arches be?+
Often 0.5–1 m center-to-center. Closer spacing stiffens the tunnel in wind and snow; wider spacing saves steel but flaps more. Follow the kit manual if you buy a set.
Do I need extra film for doors?+
End panels are included as solid sheets in the estimate. If you cut doors or buy framed door kits, keep 10% spare from the roll for patches and mistakes.
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