Convert Foot-pound to british thermal unit

The British thermal unit, the heat that warms a pound of water by one degree Fahrenheit (1,055 J), is now mostly an American unit. US gas bills are in therms of 100,000 Btu (29.3 kWh), wholesale gas is priced per million Btu (MMBtu), and national energy statistics are in quads, 10¹⁵ Btu: the US uses about 100 quads a year. The ton-hour is the cooling delivered by one refrigeration ton over an hour, 12,000 Btu.

The foot-pound is the work of a one-pound force over one foot, 1.356 J. It is used in the US for the muzzle energy of firearms and airguns (a .22 rifle delivers about 100 ft·lb, a hunting rifle 2,000–3,000) and for the impact energy of tools and hammers. Do not confuse it with the pound-foot of torque: the same product of force and distance, but nothing moves, so it is not energy.