BTU/(h·ft²·°F)
The BTU per hour square foot degree Fahrenheit is the US unit of heat transfer coefficient and U-factor, exactly 5.678263341 W/(m²·K). A double-glazed window has a U-factor of about 0.3–0.5.
Symbol: BTU/(h·ft²·°F) (ASCII: BTU/(h*ft2*F))
Quantity: heat transfer coefficient (h) and thermal transmittance (U-value)
SI relation: 1 BTU/(h·ft²·°F) = 5.678263341113 W/(m²·K) (exact)
Derivation: 1 BTU_IT/(h·ft²·°F) = 1055.05585262 J ÷ (3600 s × 0.09290304 m² × 5/9 K) = 5.678263341 W/(m²·K) (exact)
Exact: yes, by definition
Typical uses
- US window and building U-factors (NFRC, ASHRAE)
- Heat exchanger overall U in US practice
- R-value conversion (R = 1/U in h·ft²·°F/BTU)
Convert BTU per hour square foot degree Fahrenheit to other units
Open the Heat Transfer Coefficient Converter to convert any value between all units.
Sources
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "British thermal unit_IT per hour square foot degree Fahrenheit [Btu_IT/(h · ft² · °F)]".
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). BTU/(h·ft²·°F). Retrieved October 25, 2026, from https://scientificconverters.com/units/btu-per-hour-square-foot-fahrenheit/
IEEE
Scientific Converters, "BTU/(h·ft²·°F)," scientificconverters.com. Accessed: Oct. 25, 2026. [Online]. Available: https://scientificconverters.com/units/btu-per-hour-square-foot-fahrenheit/