Insulation Calculator
Estimate insulation material for a rectangular area such as an attic, wall or ceiling. Enter the area and coverage per pack or roll.
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How the insulation calculator works
Estimate insulation material for a rectangular area such as an attic, wall or ceiling. Enter the area and coverage per pack or roll.
Required insulation = project area × (1 + waste%). Packs = required insulation ÷ package coverage, rounded up. The calculator is designed to give a useful first-pass material estimate while keeping the assumptions visible. For a purchase, compare the result with the product packaging or supplier quotation.
Common search terms for this tool include insulation calculator, insulation roll calculator, how much insulation do I need, loft insulation calculator. The wording is included naturally so the page answers the same questions people ask when planning a project.
Frequently asked questions
How much insulation do I need?
Measure the surface area and use the coverage printed on the product packaging.
Should I add waste?
Yes. Cutting and fitting around openings creates offcuts.
Does this choose insulation thickness?
No. Thickness and thermal performance depend on your climate, building design and local requirements.
Can I use it for loft insulation?
Yes, provided the product's coverage is entered correctly.