Amount of energy needed to raise the temperature of 1 lb of water 1°F.
A unit of heat equal to the quantity of heat required to raise the temperature of 1 pound of water by 1° Fahrenheit. 1 British thermal unit = 1055 joules.
The amount of heat necessary to raise the temperature of 1 lb of water from 39°F to 40°F.
The amount of heat necessary to raise the temperature of one pound of water by one degree Fahrenheit at standard atmospheric pressure is approximately 252 gram-calories.