R-value (US) (ft²·°F·h/BTU)
US unit of thermal insulance: square foot degree Fahrenheit hour per BTU (IT). An "R-13" wall has 13 of these.
What is an R-value (US)?
- Symbol
- ft²·°F·h/BTU
- Quantity
- Thermal Insulance (R-value)
- Unit system
- US customary
- Definition
- US unit of thermal insulance: square foot degree Fahrenheit hour per BTU (IT). An "R-13" wall has 13 of these.
- Exact
- Yes, the value is exact by definition
- Source
- NIST Special Publication 811 (2008), Appendix B.8
Common applications
Printed on insulation products in the United States and used in building codes, as in R-13 wall batts or R-38 attic insulation.
R-value (US) in other thermal insulance (r-value) units
- 1 ft²·°F·h/BTU ≈ 0.1761101837 m²·K/WR-value (US) to Square meter kelvin per watt (RSI) converter
- 1 ft²·°F·h/BTU ≈ 1.136194733 cloClo
- 1 ft²·°F·h/BTU ≈ 1.761101837 togTog
R-value (US) quick reference
| R-value (US) | Square meter kelvin per watt (RSI) | Clo | Tog |
|---|---|---|---|
| 1 ft²·°F·h/BTU | ≈ 0.1761101837 m²·K/W | ≈ 1.136194733 clo | ≈ 1.761101837 tog |
| 10 ft²·°F·h/BTU | ≈ 1.761101837 m²·K/W | ≈ 11.36194733 clo | ≈ 17.61101837 tog |
| 100 ft²·°F·h/BTU | ≈ 17.61101837 m²·K/W | ≈ 113.6194733 clo | ≈ 176.1101837 tog |
| 1000 ft²·°F·h/BTU | ≈ 176.1101837 m²·K/W | ≈ 1136.194733 clo | ≈ 1761.101837 tog |
Where the R-value (US) fits
The next smaller thermal insulance (r-value) unit is the clo (clo). 1 ft²·°F·h/BTU ≈ 1.136194733 clo, and 1 clo ≈ 0.8801308179 ft²·°F·h/BTU.
The next larger thermal insulance (r-value) unit is the square meter kelvin per watt (m²·K/W). 1 ft²·°F·h/BTU ≈ 0.1761101837 m²·K/W, and 1 m²·K/W ≈ 5.678263341 ft²·°F·h/BTU.
Frequently asked questions
- How many square meter kelvins per watt are in one R-value (US)?
- One R-value (US) ≈ 0.1761101837 m²·K/W (square meter kelvins per watt).
- How many clo are in one R-value (US)?
- One R-value (US) ≈ 1.136194733 clo (clo).
- How many togs are in one R-value (US)?
- One R-value (US) ≈ 1.761101837 tog (togs).