Per Degree Fahrenheit (°F⁻¹)
Per degree Fahrenheit (1/°F, also written in/in/°F) is the US customary unit of the expansion coefficient. Because a Fahrenheit degree is smaller, the number is 1/1.8 of the per-kelvin value: steel is about 6.5 × 10⁻⁶ /°F.
Symbol: °F⁻¹ (ASCII: 1/°F)
Quantity: coefficient of thermal expansion (α, CTE)
SI relation: 1 °F⁻¹ = 1.8 K⁻¹ (exact)
Derivation: A Fahrenheit degree is 5/9 of a kelvin, so 1/°F = 1.8/K (exact)
Exact: yes, by definition
Typical uses
- US piping and structural codes (ASME B31, AISC)
- US material datasheets
Convert per degree Fahrenheit to other units
| Conversion | 1 °F⁻¹ equals | Reverse |
|---|---|---|
| per degree Fahrenheit to per kelvin | 1.8 K⁻¹ | per kelvin to per degree Fahrenheit |
| per degree Fahrenheit to ppm per kelvin | 1800000 ppm/K | ppm per kelvin to per degree Fahrenheit |
| per degree Fahrenheit to per degree Celsius | 1.8 °C⁻¹ | per degree Celsius to per degree Fahrenheit |
| per degree Fahrenheit to ppm per degree Fahrenheit | 1000000 ppm/°F | ppm per degree Fahrenheit to per degree Fahrenheit |
Open the Thermal Expansion 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, "degree Fahrenheit".
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). Per Degree Fahrenheit (°F⁻¹). Retrieved October 25, 2026, from https://scientificconverters.com/units/per-degree-fahrenheit/
IEEE
Scientific Converters, "Per Degree Fahrenheit (°F⁻¹)," scientificconverters.com. Accessed: Oct. 25, 2026. [Online]. Available: https://scientificconverters.com/units/per-degree-fahrenheit/