How many British thermal units are in 1 calorie?

1 calorie equals 0.00396567 BTU.

How do I convert British thermal units back to calories?

Use the reverse converter: 1 British thermal unit equals 252.164 cal.

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

To convert calories to British thermal units, multiply the value by 0.00396566683.

BTU = cal × 0.00396566683

40 cal × 0.00396566683 = 0.1586 BTU

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

How do I convert calories to British thermal units?: To convert calories to British thermal units, multiply the value by 0.00396566683.
How many British thermal units are in 1 calorie?: 1 calorie equals 0.00396567 BTU.
How many British thermal units are in 10 calories?: 10 cal equals 0.0396567 BTU.
How do I convert British thermal units back to calories?: Use the reverse converter: 1 British thermal unit equals 252.164 cal.
Is this converter accurate?: Yes. It uses the exact SI/NIST definitions of each unit and shows up to 6 significant digits.