Insulation batt and roll calculator
Estimate insulation batts, rolls, and packages from wall or attic area, with openings and waste.
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Tool guide
Insulation batt and roll calculator: how it works
Practical information to understand the result and use this tool correctly.
About Insulation batt and roll calculator
Enter walls as length times height times how many walls you are insulating, an attic as length times width, or a known area. Openings (windows and doors) are subtracted before waste, and cannot be larger than the gross area.
Order area is the net area times 1 plus the waste percent. Pieces are that area divided by one batt, panel, or roll, rounded up. Packages are pieces divided by how many come in a bag, also rounded up. A US R-13 batt is about 15 in by 93 in (roughly 9.7 ft²); a common mineral-wool panel is 0.6 m by 1.2 m.
Presets set typical piece size and bag count for R-13 walls, R-30 attic rolls, and metric panels. They do not pick an R-value for your climate. Match the cavity depth (about 3.5 in / 89 mm for a 2x4 wall, 5.5 in / 140 mm for a 2x6) and the labeled coverage on the package you buy.
This is a material count, not a heat-loss or code check, and it does not replace the drywall sheet calculator or the wallpaper roll calculator. Nothing is uploaded. Zero, negative, and oversized areas are rejected.
How to use it
- 1Choose meters or feet, then walls, an attic, or a known area.
- 2Pick an R-13, attic-roll, or metric-panel preset, or enter piece size and pieces per pack.
- 3Subtract window and door area, set waste, and add an optional pack price.
- 4Review net area, pieces, and packages, then copy the order.
Frequently asked questions
- How is the insulation count calculated?
- Gross area is wall length × height × wall count, attic length × width, or the area you type. Net area subtracts openings. Order area is net × (1 + waste). Pieces are order area divided by one piece, rounded up. Packages are pieces divided by the bag count, rounded up.
- Does this replace the drywall or wallpaper calculator?
- No. Drywall counts sheets, joint compound, and screws. Wallpaper counts rolls from drop length. This tool only counts insulation batts, panels, rolls, and packages.
- Which R-value should I buy?
- The presets only set a common piece size. R-13 is a typical 2x4 wall batt and R-30 is a common attic roll in mild US climates; colder roofs often need more. Check the package coverage and local energy code before ordering.
- Does the calculation leave the browser?
- No. Areas, prices, and the order summary stay on your device.