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Calories to British Thermal Units Converter

Convert calories (thermochemical) (cal) to British thermal units (IT) (Btu), with the formula, a conversion table and exact factors.

Change the values and press Calculate to work out your own figures.

Enter an amount of energy, choose its unit and the unit you want. The answer is exact until it is shown, and the same value appears in every other unit.

A number, fraction (3/8), mixed number (1 1/2), scientific notation (2.5e6) or a simple sum such as 2*3.
The unit you want the answer in. Swap exchanges the two units.
Result
0.00396566683139 Btu
joules (watt-seconds)
4.184 J
kilojoules
0.004184 kJ
megajoules
4.184 × 10⁻⁶ MJ
gigajoules
4.184 × 10⁻⁹ GJ
kilocalories (food Calories)
0.001 kcal
megacalories
1 × 10⁻⁶ Mcal
watt-hours
0.00116222222222 Wh
kilowatt-hours
1.16222222222 × 10⁻⁶ kWh
megawatt-hours
1.16222222222 × 10⁻⁹ MWh
million Btu
3.96566683139 × 10⁻⁹ MMBtu
therms (100,000 Btu)
3.96566683139 × 10⁻⁸ thm
quads (10¹⁵ Btu)
3.96566683139 × 10⁻¹⁸ quad
electronvolts
2.61144739675 × 10¹⁹ eV
kiloelectronvolts
2.61144739675 × 10¹⁶ keV
megaelectronvolts
26,114,473,967,500 MeV

1 cal = 0.00396566683139 Btu

Show the working
  1. 1 cal = 0.00396566683139 Btu
  2. 1 × 0.00396566683139 = 0.00396566683139 Btu

How to convert calories to british thermal units

1 cal = 0.00396566683139 Btu, so multiply by 0.00396566683139 to go from calories (thermochemical) to British thermal units (IT). Going the other way, 1 Btu = 252.164400722 cal.

Btu = cal × 0.00396566683139
cal = Btu × 252.164400722

Worked example:

1 cal = 0.00396566683139 Btu
5 × 0.00396566683139 = 0.019828334157 Btu

Calories to british thermal units table

CaloriesBritish Thermal Units
1 cal0.00396566683139 Btu
2 cal0.00793133366278 Btu
3 cal0.0118970004942 Btu
4 cal0.0158626673256 Btu
5 cal0.019828334157 Btu
6 cal0.0237940009883 Btu
7 cal0.0277596678197 Btu
8 cal0.0317253346511 Btu
9 cal0.0356910014825 Btu
10 cal0.0396566683139 Btu
15 cal0.0594850024709 Btu
20 cal0.0793133366278 Btu
25 cal0.0991416707848 Btu
30 cal0.118970004942 Btu
40 cal0.158626673256 Btu
50 cal0.19828334157 Btu
75 cal0.297425012354 Btu
100 cal0.396566683139 Btu
250 cal0.991416707848 Btu
500 cal1.9828334157 Btu
1000 cal3.96566683139 Btu

About the units

Calories (cal)
Calories (thermochemical), a specialised unit. The thermochemical calorie, 4.184 J, used on US food labels as 1 Calorie = 1 kilocalorie. Definition: NIST SP 811 Appendix B.8, factors for units listed alphabetically.
British Thermal Units (Btu)
British thermal units (IT), a US customary unit. Definition: NIST SP 811 Appendix B.8, factors for units listed alphabetically.

Formula version 0.1.0Reviewed