Insulation Calculator
Work out how many insulation boards or rolls you need.
Boards or rolls
11
- Coverage each
- 2.88 m²
v1.0 · Reviewed September 2026
How this is worked out
The area to insulate is divided by the coverage of one board or roll, multiplied by any waste allowance, then rounded up.
Worked example
- Area 30 m²
- Board 2.4 m × 1.2 m
- No waste allowance
30 ÷ 2.88 = 10.4, rounded up
11 boards or rolls
Assumptions and limits
- Counts by area only, so it does not allow for cutting to fit joist or stud spacings.
- The thickness needed to meet building regulations is a separate question from how many boards cover the area.