Expanding foam calculator: how many cans of PU foam?
How many cans of PU foam do you need? Enter windows and doors or the joint length – the calculation uses the joint yield according to the data sheet, not the free-foam volume.
–cans
Metres of joint per can apply to the standard joint according to the data sheet. Wider or deeper joints need correspondingly more. At a window, foam is only the insulation layer – a sealing layer is also needed inside and outside (RAL installation).
Calculation:
joint length [m] ÷ metres of joint per can (data sheet), rounded up. Joint length from window dimensions: number × 2 × (width + height).
Guide value according to the manufacturer's data sheet, as of 01.10.2026. Matching products
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The can usually states the free-rise volume. In the joint, however, 1K foam expands to only a fraction of that. This calculator therefore works with the joint yield in metres per can, as the manufacturers state it in the data sheet.