Convert calorie to British thermal unit
1 cal = 0.003965666831 BTU
1 cal = 0.0039657 BTU
1 cal in every energy unit
| electron volt | 2.6114e+19 eV |
| hartree | 9.5969e+17 Eh |
| kiloelectron volt | 2.6114e+16 keV |
| megaelectron volt | 26,114,000,000,000 MeV |
| gigaelectron volt | 26,114,000,000 GeV |
| nanojoule | 4,184,000,000 nJ |
| erg | 41,840,000 erg |
| teraelectron volt | 26,114,000 TeV |
| microjoule | 4,184,000 µJ |
| millijoule | 4,184 mJ |
| inch-pound | 37.032 in·lb |
| joule | 4.184 J |
| foot-pound | 3.086 ft⋅lb |
| calorie | 1 cal |
| calorie (International Table) | 0.99933 cal IT |
| kilojoule | 0.004184 kJ |
| BTU (thermochemical) | 0.0039683 BTU th |
| British thermal unit | 0.0039657 BTU |
| watt-hour | 0.0011622 Wh |
| kilocalorie | 0.001 kcal |
| megajoule | 0.000004184 MJ |
| horsepower-hour | 0.0000015586 hp·h |
| kilowatt-hour | 0.0000011622 kWh |
| therm | 3.9657e-08 therm |
| gigajoule | 4.1840e-09 GJ |
| million BTU | 3.9657e-09 MMBTU |
| megawatt-hour | 1.1622e-09 MWh |
| ton of TNT | 1.0000e-09 t TNT |
| tonne of oil equivalent | 9.9933e-11 toe |
| terajoule | 4.1840e-12 TJ |
| gigawatt-hour | 1.1622e-12 GWh |
| kiloton of TNT | 1.0000e-12 kt TNT |
| petajoule | 4.1840e-15 PJ |
| terawatt-hour | 1.1622e-15 TWh |
| megaton of TNT | 1.0000e-15 Mt TNT |
| quad | 3.9657e-18 quad |
How the conversion works
Multiply by 0.003965666831 to go from calorie to British thermal unit, or divide by it to go back. Every conversion on this site routes through the SI value (J) rather than a table of pairwise factors, so a round-trip returns exactly what you started with.
Going the other way? British thermal unit to calorie — 1 BTU = 252.1644007 cal.
calorie to British thermal unit — common values
| 1 cal | 0.0039656668 BTU |
| 2 cal | 0.0079313337 BTU |
| 3 cal | 0.011897 BTU |
| 5 cal | 0.019828334 BTU |
| 10 cal | 0.039656668 BTU |
| 15 cal | 0.059485002 BTU |
| 20 cal | 0.079313337 BTU |
| 25 cal | 0.099141671 BTU |
| 50 cal | 0.19828334 BTU |
| 75 cal | 0.29742501 BTU |
| 100 cal | 0.39656668 BTU |
| 250 cal | 0.99141671 BTU |
| 500 cal | 1.9828334 BTU |
| 1000 cal | 3.9656668 BTU |