\(\text{cal/(g·°C)}\) is the specific heat capacity expressed in calories per gram per degree Celsius. It tells how many calories are needed to raise the temperature of one gram of a substance by one degree Celsius.
\(\text{BTU/(lb·°F)}\) is the same property expressed in British thermal units per pound per degree Fahrenheit. One BTU is the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit.
Why Convert?
Engineering calculations in the United States often use BTU/(lb·°F) while many scientific texts use cal/(g·°C).
Accurate conversion is essential for thermal design of heat exchangers, HVAC systems, and material processing.
The conversion factor is very close to 1, but the slight difference can matter in high‑precision energy balances.
It means that raising the temperature of 1 g of the material by 1 °C requires 1 calorie of energy. In the U.S. system this is equivalent to about 0.9993 BTU per pound per °F, which is useful when sizing heating or cooling equipment.
The factor differs from 1 because the calorie, gram, and Celsius are defined in the metric system, while the BTU, pound, and Fahrenheit belong to the Imperial system. Their base definitions involve different energy, mass, and temperature increments, leading to the precise factor 0.9993312314894429.
"On fait la science avec des faits, comme on fait une maison avec des pierres ; mais une accumulation de faits n'est pas plus une science qu'un tas de pierres n'est une maison." "Science is built up of facts, as a house is built of stones; but an accumulation of facts is no more a science than a heap of stones is a house." — Henri Poincaré (French Mathematician, Theoretical Physicist & Mining Engineer)