Insulation batts Calculator by Area
Work out how much insulation batts you need for a floor, wall or surface. Enter the length and width, the number of coats and a waste allowance.…
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Work out how much insulation batts you need for a floor, wall or surface. Enter the length and width, the number of coats and a waste allowance. Based on coverage of 7.8 m² per packs of 7.8 m².
Worked example
Example calculated from the starting values. Enter your own values and press Calculate to get your result.
With the default inputs (length = 5 m, width = 4 m, coats or layers = 1, waste allowance = %5), the results are: area covered 20.00 m²; insulation batts needed 3 packs of 7.8 m².
Quick reference: length vs result
Reference table based on the example values; it is not your calculation result.
| Length (m) | Area covered | Insulation batts needed |
|---|---|---|
| 2.5 | 10.00 m² | 2 packs of 7.8 m² |
| 5 | 20.00 m² | 3 packs of 7.8 m² |
| 10 | 40.00 m² | 6 packs of 7.8 m² |
| 25 | 100.00 m² | 14 packs of 7.8 m² |
| 50 | 200.00 m² | 27 packs of 7.8 m² |
| 100 | 400.00 m² | 54 packs of 7.8 m² |
Frequently asked questions
What formula does this calculator use?
Area covered = length × width; Insulation batts needed = ceil(length × width × coats ÷ cov × (1+waste ÷ 100)). Variables: length = length in m, width = width in m, coats = coats or layers, waste = waste allowance in %. Fixed values: cov = 7.8.
What do I need to enter?
You need length (m), width (m), coats or layers, waste allowance (%). Results update as you type.
What is an example result?
With the default inputs (length = 5 m, width = 4 m, coats or layers = 1, waste allowance = %5), the results are: area covered 20.00 m²; insulation batts needed 3 packs of 7.8 m².
What coverage does this assume?
It assumes one packs of 7.8 m² covers 7.8 m² per coat. Always check the coverage printed on your product, because it varies by brand and surface.
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