Insulation R-Value Calculator

Calculate insulation R-values and required thickness instantly — built for contractors and builders.

Not sure if your wall insulation meets code for your climate zone? This calculator instantly converts between R-value and thickness for 9 common materials — and shows you IECC minimum requirements so you pass inspection the first time.

Select an insulation material, enter thickness to get R-value, or enter target R-value to find required thickness. Built-in IECC climate zone reference shows minimum R-values for walls, ceilings, and floors at a glance.

WHAT IT CALCULATES:

R-Value from Thickness:

• Select an insulation material from the built-in list
• Enter the installed thickness in inches
• Get the total R-value and U-factor instantly

Required Thickness:

• Choose your insulation material
• Enter your target R-value
• See the exact thickness needed to meet that R-value

MATERIALS INCLUDED:

• Fiberglass Batt (R-3.2/in)
• Fiberglass Blown (R-2.5/in)
• Cellulose Blown (R-3.5/in)
• Mineral Wool (R-3.3/in)
• XPS Foam Board (R-5.0/in)
• EPS Foam Board (R-3.8/in)
• Polyisocyanurate (R-6.0/in)
• Spray Foam Open Cell (R-3.6/in)
• Spray Foam Closed Cell (R-6.5/in)

IECC CLIMATE ZONE REFERENCE:

• Built-in IECC climate zone lookup (Zones 1 through 7-8)
• See minimum R-value requirements for walls, ceilings, and floors
• Quickly check if your insulation meets code for your zone

KEY FEATURES:

• Two-way calculator: R-value from thickness or thickness from R-value
• U-factor output for energy calculations
• 9 common insulation materials with accurate R-per-inch values
• IECC climate zone minimum requirements built in
• Works completely offline
• No account or login required

BUILT FOR THE JOB SITE:

Whether you are an insulation contractor, general contractor, home inspector, or energy auditor, InsulR Calc gives you quick R-value lookups and thickness calculations. Enter your material and thickness to get R-value, or enter your target R-value to find required thickness in seconds.

Supports all common residential and commercial insulation materials per IECC and ASHRAE standards.