Convert cal/(s·cm²·°C) to BTU/(h·ft²·°F)

Formula

BTU/(h·ft²·°F) = cal/(s·cm²·°C) × 7368.450085268

Derivation from SI units:

• 1 cal_th/(s·cm²·°C) = 4.184 J ÷ (1 s × 10⁻⁴ m² × 1 K) = 41 840 W/(m²·K) (exact)
• 1 BTU_IT/(h·ft²·°F) = 1055.05585262 J ÷ (3600 s × 0.09290304 m² × 5/9 K) = 5.678263341 W/(m²·K) (exact)
• 1 cal/(s·cm²·°C) = 41840 W/(m²·K) ÷ 5.678263341113 W/(m²·K) per BTU/(h·ft²·°F) = 7368.450085268 BTU/(h·ft²·°F)

Both units are defined exactly, so the factor is exact. cal/(s·cm²·°C) definition: calorie per second square centimetre degree Celsius; BTU/(h·ft²·°F) definition: BTU per hour square foot degree Fahrenheit.

Worked examples

1. A reading of 0.001 cal/(s·cm²·°C) converts to 7.368450085 BTU/(h·ft²·°F).
   0.001 cal/(s·cm²·°C) × 7368.450085 = 7.368450085 BTU/(h·ft²·°F)
2. A value of 0.05 cal/(s·cm²·°C) is 368.4225043 BTU/(h·ft²·°F).
   0.05 cal/(s·cm²·°C) × 7368.450085 = 368.4225043 BTU/(h·ft²·°F)

Where it's used

cal/(s·cm²·°C) are used for older scientific and metallurgical literature, while BTU per hour square foot degree Fahrenheit appear in US window and building U-factors (NFRC, ASHRAE). Both measure heat transfer coefficient (h) and thermal transmittance (U-value), so the conversion is a fixed factor.

cal/(s·cm²·°C) to other heat transfer coefficient units

Frequently asked questions

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, "calorie_th".
• 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: 2026-10-15. Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.