Thermal Insulance (R-value) Converter
Convert insulation R-values between US R-value (ft²·°F·h/BTU), RSI (m²·K/W), clo and tog.
Convert thermal insulance (r-value)
Result
Thermal Insulance (R-value) units
Every unit below converts to every other one in the calculator. Values are relative to the base unit, the square meter kelvin per watt (rsi) (m²·K/W).
| Unit | Symbol | System | Value |
|---|---|---|---|
| Square meter kelvin per watt (RSI) | m²·K/W | SI | Base unit |
| R-value (US) | ft²·°F·h/BTU | US customary | ≈ 0.1761101837 m²·K/W |
| Clo | clo | other | = 0.155 m²·K/W |
| Tog | tog | other | = 0.1 m²·K/W |
Square meter kelvin per watt (RSI) quick reference
| Square meter kelvin per watt (RSI) | R-value (US) |
|---|---|
| 1 m²·K/W | ≈ 5.678263341 ft²·°F·h/BTU |
| 10 m²·K/W | ≈ 56.78263341 ft²·°F·h/BTU |
| 100 m²·K/W | ≈ 567.8263341 ft²·°F·h/BTU |
| 1000 m²·K/W | ≈ 5678.263341 ft²·°F·h/BTU |
Among the 4 thermal insulance (r-value) units on this page, the smallest is the tog (tog) and the largest is the square meter kelvin per watt (rsi) (m²·K/W).
More thermal insulance (r-value) conversions
About thermal insulance (r-value) units
Thermal insulance, usually called R-value, measures how well a layer of insulation, clothing or bedding resists heat flow per unit area. Higher is better. Its SI unit is the square meter kelvin per watt (m²·K/W), often written RSI. The R-values of layers stacked together add up.
US R-values use ft²·°F·h/BTU: one US unit is about 0.17611 m²·K/W, so R-13 is about RSI 2.29. Clothing uses the clo (0.155 m²·K/W) and bedding the tog (exactly 0.1 m²·K/W). The U-value is the reciprocal of the total R-value.
Frequently asked questions
- How do I convert a US R-value to RSI?
- Multiply by about 0.17611, or divide by about 5.6783. For example, R-19 is about RSI 3.35.
- What is the difference between R-value and U-value?
- The U-value is 1 ÷ total R-value. An assembly with RSI 4 m²·K/W has a U-value of 0.25 W/(m²·K). Higher R means better insulation; lower U means the same.
- How many tog is 1 clo?
- Exactly 1.55 tog, because 1 clo is 0.155 m²·K/W and 1 tog is 0.1 m²·K/W.
- How many R-value units (US) are in one square meter kelvin per watt?
- One square meter kelvin per watt ≈ 5.678263341 ft²·°F·h/BTU (R-value units (US)).