Insulation Calculators
Cut energy bills with the right amount of insulation. Use our tools as a wall insulation calculator, a whole house insulation calculator, or a blown-in insulation estimator. Enter your square feet and insulation type. You get material and installed-cost estimates for fiberglass batts, blown-in cellulose insulation, and spray foam. Each result includes the R-value target for your climate, so you can meet local building codes. Explore the tools and cost guides below.
Insulation calculators
What you can estimate
- Square footage to insulate (walls or attic)
- Cost by insulation type
- R-value targets for walls and attics
- Batt, blown-in cellulose, and spray foam pricing
How to estimate insulation
Insulation is estimated by the square foot of the surface you're covering — a wall, or the attic floor. Measure length × width for the area, then choose an insulation type based on the R-value your climate needs. R-value measures resistance to heat flow: most attics target R-38 to R-60, while walls need R-13 to R-21. Higher R-value means more material or a higher-performance product like spray foam.
Our insulation calculator converts your area and chosen type into a material and installed-cost estimate, so you can compare fiberglass batts, blown-in cellulose, and spray foam side by side before hiring a contractor or buying supplies.
Insulation types and cost
The three common options trade off price against performance. Batts are cheapest and DIY-friendly, blown-in is ideal for attics and retrofits, and spray foam delivers the highest R-value per inch while air-sealing at the same time.
| Type | Installed cost / ft² | R-value per inch | Best for |
|---|---|---|---|
| Fiberglass batt | $1.00 – $2.40 | R-3.1 | Walls, budget jobs |
| Blown-in cellulose | $1.00 – $2.50 | R-3.5 | Attics, retrofits |
| Closed-cell spray foam | $3.00 – $7.00 | R-6.5 | Air-sealing, rim joists |
Insulation tips
- The attic gives the biggest energy return — insulate it first.
- Air-seal gaps and penetrations before adding insulation for full effect.
- Don't compress batts; squeezing them into tight cavities lowers R-value.
- In cold climates, use a vapor barrier on the warm side of the wall.