Convert energy units — joules, calories, kilowatt-hours, BTU, kilojoules.
| Unit | Name | Value |
|---|---|---|
| J | Joule | 1055.06 |
| kJ | Kilojoule | 1.05506 |
| cal | Calorie | 252.16539 |
| kcal | Kilocalorie (Cal) | 0.25216539 |
| kWh | Kilowatt-hour | 0.00029307222 |
Formula: Kilocalorie = BTU × 0.2522
Multiply any btu value by 0.2522 to get kilocalorie.
Reverse: BTU = Kilocalorie × 3.966
Common btu values — factor: 1 BTU = 0.2522 kcal
| BTU (BTU) | Kilocalorie (kcal) | Context |
|---|---|---|
| 1 BTU | 0.2522 kcal | Match |
| 10 BTU | 2.522 kcal | 10 BTU |
| 100 BTU | 25.22 kcal | Space heater second |
| 1,000 BTU | 252.2 kcal | 1 kBTU |
| 3,412 BTU | 860.4 kcal | 1 kWh |
| 1e+04 BTU | 2,522 kcal | 10 kBTU |
| 1e+05 BTU | 2.522e+04 kcal | 1 therm |
| 1e+06 BTU | 2.522e+05 kcal | 1 MMBTU |
| 1e+07 BTU | 2.522e+06 kcal | 10 MMBTU |
| 1e+08 BTU | 2.522e+07 kcal | 100 MMBTU |
| 1.000e+09 BTU | 2.522e+08 kcal | 1 billion BTU |
| 1.000e+10 BTU | 2.522e+09 kcal | 10 billion BTU |
| 1.000e+12 BTU | 2.522e+11 kcal | 1 quad fraction |
| 1.000e+15 BTU | 2.522e+14 kcal | 1 quad |
| 1.000e+18 BTU | 2.522e+17 kcal | 1000 quads |
1 BTU = 0.2522 kcal. Memorize for instant estimates.
Use 0.2522 as a quick mental multiplier.
Multiply result by 3.966 to recover the original BTU value.
Sizes heating and cooling systems rated in BTU/hour for US buildings.
Certifies boiler output and efficiency ratings in BTU/hour.
Prices natural gas supply and usage in BTU and therms.
Calculates heating loads and heat loss in BTU for US properties.
Rates commercial refrigeration and ice-making capacity in BTU.
Specifies heat exchanger capacity and furnace output in BTU/hour.
The British Thermal Unit (BTU) is the traditional Imperial energy unit, defined as the heat required to raise 1 pound of water by 1°F. It equals 1,055.06 joules and has been used since the 19th century in heating, air conditioning, and gas billing.
BTU remains dominant in US HVAC: air conditioners and heaters are rated in BTU/hour. Natural gas is priced in therms (100,000 BTU) in the US. Furnaces are rated in BTU/hour output.
Interesting fact: A typical US home furnace is rated at 80,000–120,000 BTU/hour. One BTU is roughly the energy released by burning one kitchen match. The US natural gas pipeline system delivers about 25 quadrillion BTU (quads) per year.
The kilocalorie (kcal) equals 1,000 calories or 4,184 joules, and is the unit used on food labels worldwide (often written as 'Cal' with a capital C in the US). It was standardized by the International Table calorie in 1956.
Nutritionists, dietitians, and food scientists use kcal for daily energy intake recommendations. Most adults need 2,000–2,500 kcal/day. Exercise apps, fitness trackers, and dietary plans all operate on kcal.
Interesting fact: One gram of fat yields about 9 kcal, one gram of carbohydrate or protein yields about 4 kcal. A single sugar cube (4g) contains about 16 kcal.
Converting btu to kilocalorie is common across energy, nutrition, engineering, and science. Different sectors use different energy units — joules in physics, kcal in nutrition, kWh in electricity, and BTU in HVAC — making accurate conversion essential for cross-disciplinary work and international comparisons.
Quick reference: 5 BTU = 1.261 kcal and 10 BTU = 2.522 kcal. Reverse: 1 kcal = 3.966 BTU. Exact factor: 1 BTU = 0.2522 kcal.
All conversions use IEEE 754 double-precision arithmetic, accurate to at least 8 significant figures.