Calculators

Insulation R-Value Calculator

Pick your climate zone and the assembly. Get the R-value code wants, the thickness each material needs to reach it, and which material makes sense where.

IECC residential climate zones. Kansas is Zone 5.
Leave blank to use IECC code minimum for your zone + assembly. Enter a higher R to see thickness for above-code.
Used for rough material-cost estimates below.

Target R-value

Code minimum (IECC)—

Thickness needed, by material

Price & Estimate Disclaimer Prices shown are estimates only, based on publicly observed pricing as of April 2026. Actual prices for batts, blown, rigid, and spray foam insulation vary by location, season, and market conditions and can change without notice. You are responsible for verifying current pricing with the retailer or installer before purchase. R-values are nominal and do not account for thermal bridging, air infiltration, or installation quality. See the full Terms of Use.

Built for Homeject — upscale living, self-made.

R-values and zone requirements verified from a real HOMEJECT insulation project. See the full build for context on assembly choices.

Related calculators: Insulating a new build? Start with the wall framing calculator to estimate your stud count, then use the concrete volume calculator for your foundation.

← Back to all Free DIY Home Calculators