Primary material
6 packages / bags
Batts, rolls, or blown-in
Use the count as a buying starting point, then confirm the exact product coverage, R-value, width, and faced vs unfaced before ordering.
Insulation calculator
Insulation calculator for batts, rolls, and blown-in.
Enter the area and R-value to estimate insulation packages or bags. A 500 sq ft section in R-13 batts needs about 6 packages. Coverage auto-fills from the R-value and form.
500 sq ft, R-13 batt
6 packages
~88 sq ft each
Attic R-value
R-38-60
DOE, by climate zone
Higher R
less / bag
more depth needed
Recommended R-value
How much R-value you need (DOE)
The U.S. Department of Energy sets recommended R-values by climate zone and location. Colder zones need more; warmer zones need less. Use these as a starting point and check your local code.
| Where | Recommended R | Notes |
|---|---|---|
| Attic / ceiling | R-38 to R-60 | Higher in cold climate zones (DOE 6-8) |
| Exterior walls | R-13 to R-21 | R-13/15 in 2x4, R-19/21 in 2x6 |
| Floors / crawlspace | R-25 to R-30 | Over unconditioned space |
Quick answers
12 x 12 room walls
5 packages (R-13 batts)
1,000 sq ft attic
23 bags (R-38 blown-in)
500 sq ft wall
7 packages (R-19 batts)
Shopping list
Insulation, barrier, and gear
The count updates from the calculator. Confirm product coverage, R-value, facing, and depth before ordering.
Faced vs unfaced
Vapor barrier and faced batts
Walls and crawlspaces often need a vapor retarder; attics over a finished ceiling usually use unfaced. Match the facing to your climate and assembly.
Blown-in
Blower rental and bags
Blown-in attics use a rented blowing machine plus loose-fill bags. Stores often lend the machine free with a minimum bag purchase.
Safety gear
Mask, gloves, and goggles
Fiberglass needs a rated respirator, gloves, long sleeves, and eye protection, plus baffles to keep soffit vents clear in an attic.
Formula shown
How the insulation estimate works
1. Area and R-value
measure the surface area; pick the target R for the location
2. Coverage per unit
batt package or blown-in bag covers fewer sq ft as R rises
3. Packages or bags
units = ceil(area x (1 + waste) / coverage per unit)
Coverage varies — check the bag
Package and bag coverage differs by brand, batt width, and the rated R. Blown-in bags also list a minimum install depth and bags per 1,000 sq ft for each R-value. Use those charts for the final order, and never compress batts below their rated thickness.
Sources
- DOE Energy Saver insulation — recommended R-values by climate zone and location
- NAIMA Insulation Institute — fiberglass batt coverage and compressed R-values
- Owens Corning / Johns Manville charts — batt package and blown-in bag coverage by R-value
Sources checked
Checked against
Sheet, compound, and insulation coverage checked against manufacturer specs and DOE R-value guidance.
How we check our numbersLast updated: June 26, 2026
Estimate only.
This calculator is not a quote. Verify product yield, price, delivery minimums, and local conditions with your supplier or contractor before buying materials.
FAQ
Insulation calculator questions
How much insulation you need, attic R-values, blown-in bags, batts vs blown-in, and faced vs unfaced.
How much insulation do I need? + -
Divide the area to insulate by the coverage of one package or bag at your R-value. A 500 sq ft section in R-13 batts (about 88 sq ft per package) needs roughly 6 packages with 5% waste. Coverage drops as R-value rises.
What R-value do I need for my attic? + -
The U.S. Department of Energy recommends about R-38 to R-60 for attics depending on climate zone — R-38 in warm south zones, up to R-60 in the coldest. Walls are usually R-13 to R-21 and floors R-25 to R-30.
How many bags of blown-in insulation for an attic? + -
Blown-in coverage per bag falls as R rises. A 1,000 sq ft attic at R-38 needs about 23 bags at roughly 47 sq ft per bag. Always check the bag chart for your product — it lists bags per 1,000 sq ft and the install depth for each R.
Batts or blown-in? + -
Batts and rolls suit open walls, floors, and new framing with standard cavity sizes. Blown-in loose fill is faster and better for attics and irregular spaces, but needs a blower. Many attics combine a batt layer with blown-in on top.
Faced or unfaced insulation? + -
Faced (kraft or foil) batts add a vapor retarder and suit walls, basements, and crawlspaces in many climates. Unfaced batts are common when adding a second attic layer or where a separate vapor barrier is used. Match the facing to your assembly and climate.