How many calories are in 1 British thermal unit?

1 British thermal unit equals 252.164 cal.

How do I convert calories back to British thermal units?

Use the reverse converter: 1 calorie equals 0.00396567 BTU.

Yes. It uses the exact SI/NIST definitions of each unit and shows up to 6 significant digits.

To convert British thermal units to calories, multiply the value by 252.164401.

cal = BTU × 252.164401

40 BTU × 252.164401 = 10086.58 cal

British Thermal Unit (BTU): Used for heating, cooling and gas in the US. The IT BTU is about 1,055.056 joules.
Calorie (cal): The thermochemical calorie is exactly 4.184 joules, historically the heat to warm one gram of water by 1 °C.

How do I convert British thermal units to calories?: To convert British thermal units to calories, multiply the value by 252.164401.
How many calories are in 1 British thermal unit?: 1 British thermal unit equals 252.164 cal.
How many calories are in 10 British thermal units?: 10 BTU equals 2521.64 cal.
How do I convert calories back to British thermal units?: Use the reverse converter: 1 calorie equals 0.00396567 BTU.
Is this converter accurate?: Yes. It uses the exact SI/NIST definitions of each unit and shows up to 6 significant digits.