How to Calculate BTU for Heat

Metals take less energy to heat than water does.
••• Hemera Technologies/PhotoObjects.net/Getty Images

The British thermal unit (Btu) is the heat needed to raise the temperature of a pound of water by a Fahrenheit degree. Other substances, however, absorb heat at different rates, with each having their own specific heat capacity. You can use Btus to calculate their heat requirements as well, but you must take into account their heat capacities and masses.

    Subtract the substance's current temperature from the temperature you want it to reach. If, for instance, the substance is currently at 22 degrees Celsius, and you want to heat it to 31 degrees Celsius: 31 - 22 = 9 degrees.

    Multiply this temperature rise by the substance's specific heat capacity. For a list of specific heat capacities, see the first link in "Resources." If, for instance, you are heating copper, which has a heat capacity of 0.386: 9 x 0.386 = 3.474.

    Multiply the answer by the substance's weight, measured in grams. If it weighs, for instance, 1,500 grams: 3.474 x 1,500 = 5,211. This is the heat requirement, measured in joules.

    Divide this answer by 1,055, the number of joules in a Btu: 5,211 ÷ 1,055 = 4.94, or approximately 5. The substance needs 5 Btus for you to heat it to 31 degrees.

Related Articles

How to Convert Wattage to Degrees
How to Calculate Heat Absorbed by the Solution
How to Calculate Heat of Sublimation
How to Convert Joules to Kelvin
How to Calculate a Final Temperature
How to Calculate Molar Heat Capacity
How to Calculate Heat Absorption
How to Calculate the Amount of Heat Transferred
How to Calculate the Amount of Heat Released
How to Calculate Joules of Heat
How to Calculate Time to Heat Water
How to Find Heat Reaction When Zn Reacts With HCl
How Do You Convert HSFP to COP?
How to Mix Calcium Chloride and Water
How to Convert ATM Pressure to Celsius
How to Convert From BTU to Fahrenheit
How to Calculate Temperature From BTU
How to Calculate the Time to Heat an Object
How to Calculate the Change in Temperature