Insulation Calculator
Work out how much insulation you need — from the area and the coverage per pack — in packs and in cost.
Insulation is area divided by coverage, rounded up to whole packs. This calculator is that division, with the cost at your price per pack.
Enter the area and the coverage; the packs follow.
Your results
Enter your measurements and press Calculate.
Quantities are rounded up to whole tiles, planks, boxes or bags, after the wastage allowance. Cost appears only when you enter a price.
Formula
All lengths are converted to a single unit before the calculation: 1 ft = 0.3048 m, 1 in = 25.4 mm, 1 ft² = 0.09290304 m², 1 yd² = 9 ft². Material quantities are rounded up — you cannot buy part of a tile, plank or bag.
How to use this calculator
- Enter the area (length × width, or a known area).
- Enter the coverage per pack from the packaging.
- Enter the price per pack for the cost.
- Read the area, the packs needed and the total cost.
Worked example
| Wall | 4 m × 2.7 m = 10.8 m² |
|---|---|
| Coverage | 5 m² per pack |
| Packs | ceil(10.8 ÷ 5) = 3 packs |
| Cost | 3 × $25 = $75 |
Check it by hand: every step above uses the formula in the box. If your numbers match the example inputs but the calculator gives a different answer, please report it via the contact page.
Frequently asked questions
How much insulation do I need?
Measure the area, divide by the coverage per pack, and round up — you cannot buy part of a pack. A 10.8 m² wall at 5 m² per pack needs 3 packs.
What is the coverage per pack?
The area one pack covers, printed on the packaging. It depends on the product and the thickness — always use the figure for the thickness you are buying.
Do I need a vapour barrier?
It depends on the construction and the climate — insulation alone is not the whole job. Ask a professional or the product manufacturer.
Is this a substitute for building design?
No. This is a quantity calculation for planning. Insulation, structural requirements and building-code compliance vary by location — see the safety notice.
Related calculators
Estimates only. Results are for planning. Measure twice, confirm box coverage and tile sizes on the packaging you buy, and follow the manufacturer's instructions. See the disclaimer.