Insulation Calculator

Already ran Room Layout for this room? Keep this on Active project to skip re-entering area by hand.

Chained wall area

Run Room Layout first to prefill insulation with the active project's wall area.

Know the product's R-value already? Use Known R-value. Otherwise estimate from cavity depth and R-per-inch.

Areasq ftTotal wall area being insulated.Target RThe R-value you're aiming for, e.g. R-30 for an attic.Current RExisting insulation's R-value, if any. Enter 0 if there's none.Coverage per unitsq ftHow much area one bag, batt, or roll covers -- from the row of the bag's coverage chart for the depth you are installing, not the headline number on the front.Coverage is rated at RWhich R-value that coverage figure is quoted at. A bag covers far less area at R-49 than at R-30, so this is checked against the R you are installing.Cavity depthinDepth of the stud or joist cavity being filled.R per inchR-value gained per inch of thickness for the chosen product. The 3.2 default is an estimate, not a published table: fibreglass, cellulose and rigid foam all differ, so read it off the bag.

You'll need 0 units of insulation for — sq ft.

You'll need

Insulation results

Warnings

ERROR Enter the area being insulated, greater than zero.
INFO Reference estimate only. Use product-label coverage and locally applicable requirements.

Detail values

Delta R: —
Estimated R: —
Required depth: — in

Assumptions

R per inch: 3.2 per inch of thickness -- estimated. Read it off the product's own label: R per inch differs by material and by manufacturer, and no verified per-material table ships with this app.
Coverage: 50 sq ft/unit at R-30

Included: insulation coverage for the entered R-value target.

Not included: labor, delivery, permits, disposal of waste material.

Material List

About this calculator

Switch between known product coverage and an editable cavity estimate to size bags, rolls, or batts and check delta-R against a target.

FAQ

Is R per inch a product guarantee?

No. It is an editable estimate. Always confirm the R-value per inch printed on the actual product bag or roll label.

What does the insufficient cavity depth warning mean?

It flags when your entered cavity depth cannot reach the target R-value at the material's R-per-inch rate, so you can adjust depth, material, or target.

Does Mode A round up to whole bags or rolls?

Yes. Bag and roll counts are rounded up since insulation is purchased in whole units.

Disclaimer

Verify product specifications, climate zone requirements, and local code minimums before installation.