Greenhouse Film Calculator
Modelled as a half-cylinder tunnel: the curved surface (half-circumference × length) plus the two half-circle end walls. Add roughly 10% for tears and overlaps during install.
Your numbers
Film area
238.4m²
Area
216.8m²
Formula
Film area = (π×(House width÷2)×House length + π×(House width÷2)²) × (1+Waste allowance÷100)
A house with vertical side walls or a gable roof needs more film than this. If you have the frame's measured arc length, use that instead.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| House width (m) | 6 | 0.5 and up |
| House length (m) | 20 | 0.5 and up |
| Waste allowance (%)The extra bought to cover breakage and offcuts. | 10 | 0 ~ 30 |
Step by step
Quick reference table
Results when only House width (m) changes and everything else stays put.
| House width (m) | Film area (m²) | Area (m²) |
|---|---|---|
| 3 | 111.4 | 101.3 |
| 4.5 | 173 | 157.3 |
| 6 | 238.4 | 216.8 |
| 9 | 381 | 346.4 |
| 12 | 539.1 | 490.1 |
What each result means
| Result | At default values |
|---|---|
| Film area (m²)The curved surface plus both end walls of an arch-style house. | 238.4 |
| Area (m²)The space a shape covers — length squared. | 216.8 |
Common mistakes
A house with vertical side walls or a gable roof needs more film than this. If you have the frame's measured arc length, use that instead.
Glossary
- Waste allowance
- The extra bought to cover breakage and offcuts.
- Film area
- The curved surface plus both end walls of an arch-style house.
- Area
- The space a shape covers — length squared.
Frequently asked questions
QHow is Greenhouse Film Calculator calculated?
Film area = (π×(House width÷2)×House length + π×(House width÷2)²) × (1+Waste allowance÷100) — Modelled as a half-cylinder tunnel: the curved surface (half-circumference × length) plus the two half-circle end walls. Add roughly 10% for tears and overlaps during install.
QCan you walk through an example?
With House width 6m, House length 20m, Waste allowance 10%, the answer is Film area 238.4m².
QWhat do I need to enter?
Enter House width, House length, Waste allowance. The result recalculates as you type, and an empty box counts as zero.
QHow much does the answer move if I change a number?
Changing only House width (m) moves the answer to House width (m) 3 → Film area (m²) 111.4 and House width (m) 12 → Film area (m²) 539.1. The table below lays out five steps.
QHow are the numbers rounded?
Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.
QAnything to watch out for?
A house with vertical side walls or a gable roof needs more film than this. If you have the frame's measured arc length, use that instead.
Related calculators
Keep your length units consistent across inputs — mixing centimetres and metres throws results far off.