Convert British Thermal Units to Kilojoules
Instantly convert British Thermal Units (BTU) to Kilojoules (kJ) with our free online calculator.
Formula: BTU to kJ — multiply by 1.05506
Reference Table
| British Thermal Units (BTU) | Kilojoules (kJ) |
|---|---|
| 1 | 1.05506 |
| 5 | 5.2753 |
| 10 | 10.5506 |
| 25 | 26.3765 |
| 50 | 52.753 |
| 100 | 105.506 |
How to Convert British Thermal Units to Kilojoules
Formula
To convert British Thermal Units (BTU) to Kilojoules (kJ): multiply by 1.05506
Step-by-Step
- Start with your value in British Thermal Units (BTU).
- Multiply by 1.05506 to perform the conversion.
- The result is your value expressed in Kilojoules (kJ).
Conversion Factor
1 BTU = 1.05506 kJ
Reverse Factor
1 kJ = 0.947813 BTU
Worked Example
Convert 25 British Thermal Units to Kilojoules: 25 BTU = 26.3765 kJ
About British Thermal Unit (BTU)
An imperial unit of heat energy, defined as the amount of heat required to raise one pound of liquid water by 1 °F at standard conditions (≈ 1,055.06 J under the International Table definition adopted by ASHRAE and ASTM). BTUs are the universal working unit in US heating, ventilation, and air-conditioning (HVAC) per ASHRAE Handbook conventions: air-conditioner cooling capacity (12,000 BTU/h = 1 'ton' of cooling = 3.517 kW; a typical residential central AC is 2-5 tons = 24,000-60,000 BTU/h), gas furnace output (40,000-100,000 BTU/h for residential), gas-water-heater input (~30,000-50,000 BTU/h), wood-stove output ratings, and gas-fireplace BTU specs. Natural gas wholesale and retail commerce uses 'MMBTU' (one million BTU) as the standard contractual unit — a Henry Hub natural-gas futures contract is denominated in MMBTU. Natural gas itself has heating content ~1,030 BTU per standard cubic foot (scf). 1 BTU = 1,055.06 J = 0.2520 kcal = 0.000293 kWh.
About Kilojoule (kJ)
A metric unit of energy equal to exactly 1,000 joules. Kilojoules are the working unit for food-energy labelling outside the United States — Australia and New Zealand display kJ-only nutrition panels per FSANZ standards 1.2.7 / 1.2.8, the European Union requires kJ alongside kcal per EU Regulation 1169/2011, and Codex Alimentarius (the international food labelling standard) uses kJ. Reference values: a Big Mac is ~2,220 kJ, an adult daily energy intake is 8,000-10,500 kJ (about 2,000-2,500 kcal) per WHO/FAO Recommended Dietary Allowances, a 350 mL soft drink ~600 kJ. The kJ is also the natural engineering unit for small-scale mechanical work (joules per stroke on a punch press), small-cell battery capacity (e.g., a smartphone Li-ion at ~40 kJ), and small-scale thermodynamic calculations like an espresso machine's per-shot energy budget (~20 kJ). 1 kJ = 0.2389 kcal = 0.948 BTU = 277.8 mWh.
Quick Facts
- 1 British Thermal Unit equals 1.05506 Kilojoules
- 1 Kilojoule equals 0.947813 British Thermal Units
- British Thermal Unit is a unit of energy
- Kilojoule is a unit of energy
- This conversion is commonly used in nutrition, electrical billing, physics, and mechanical engineering
- The British Thermal Unit belongs to the imperial system
- The Kilojoule belongs to the metric system
Common British Thermal Unit to Kilojoule Conversions
| British Thermal Units (BTU) | Kilojoules (kJ) |
|---|---|
| 0.01 | 0.0105506 |
| 0.1 | 0.105506 |
| 0.25 | 0.263765 |
| 0.5 | 0.52753 |
| 1 | 1.05506 |
| 2 | 2.11012 |
| 3 | 3.16518 |
| 5 | 5.2753 |
| 10 | 10.5506 |
| 15 | 15.8259 |
| 20 | 21.1012 |
| 25 | 26.3765 |
| 50 | 52.753 |
| 75 | 79.1295 |
| 100 | 105.506 |
| 250 | 263.765 |
| 500 | 527.53 |
| 1000 | 1055.06 |
| 5000 | 5275.3 |
| 10000 | 10550.6 |
Understanding British Thermal Units
The British Thermal Unit (symbol: BTU) is a unit of energy. An imperial unit of heat energy, defined as the amount of heat required to raise one pound of liquid water by 1 °F at standard conditions (≈ 1,055.06 J under the International Table definition adopted by ASHRAE and ASTM). BTUs are the universal working unit in US heating, ventilation, and air-conditioning (HVAC) per ASHRAE Handbook conventions: air-conditioner cooling capacity (12,000 BTU/h = 1 'ton' of cooling = 3.517 kW; a typical residential central AC is 2-5 tons = 24,000-60,000 BTU/h), gas furnace output (40,000-100,000 BTU/h for residential), gas-water-heater input (~30,000-50,000 BTU/h), wood-stove output ratings, and gas-fireplace BTU specs. Natural gas wholesale and retail commerce uses 'MMBTU' (one million BTU) as the standard contractual unit — a Henry Hub natural-gas futures contract is denominated in MMBTU. Natural gas itself has heating content ~1,030 BTU per standard cubic foot (scf). 1 BTU = 1,055.06 J = 0.2520 kcal = 0.000293 kWh.
It belongs to the imperial measurement system.
British Thermal Units are commonly used in nutrition, electrical billing, physics, and mechanical engineering.
Understanding Kilojoules
The Kilojoule (symbol: kJ) is a unit of energy. A metric unit of energy equal to exactly 1,000 joules. Kilojoules are the working unit for food-energy labelling outside the United States — Australia and New Zealand display kJ-only nutrition panels per FSANZ standards 1.2.7 / 1.2.8, the European Union requires kJ alongside kcal per EU Regulation 1169/2011, and Codex Alimentarius (the international food labelling standard) uses kJ. Reference values: a Big Mac is ~2,220 kJ, an adult daily energy intake is 8,000-10,500 kJ (about 2,000-2,500 kcal) per WHO/FAO Recommended Dietary Allowances, a 350 mL soft drink ~600 kJ. The kJ is also the natural engineering unit for small-scale mechanical work (joules per stroke on a punch press), small-cell battery capacity (e.g., a smartphone Li-ion at ~40 kJ), and small-scale thermodynamic calculations like an espresso machine's per-shot energy budget (~20 kJ). 1 kJ = 0.2389 kcal = 0.948 BTU = 277.8 mWh.
It belongs to the metric measurement system.
Kilojoules are commonly used in nutrition, electrical billing, physics, and mechanical engineering.
Why Convert British Thermal Units to Kilojoules?
Converting energy between British Thermal Units and Kilojoules is common in physics, nutrition, and engineering. Electricity bills use kilowatt-hours, food labels list calories or kilojoules, and mechanical engineers work with joules and BTUs. Reliable conversion helps professionals and consumers compare energy values across different contexts.
Frequently Asked Questions
How do I convert British Thermal Units to Kilojoules?
An imperial unit of heat energy, defined as the amount of heat required to raise one pound of liquid water by 1 °F at standard conditions (≈ 1,055. To convert British Thermal Units to Kilojoules, multiply by 1.05506. For example, 25 BTU equals 26.3765 kJ.
How many Kilojoules are in 1 British Thermal Unit?
There are 1.05506 Kilojoules in 1 British Thermal Unit.
How many British Thermal Units are in 1 Kilojoule?
There are 0.947813 British Thermal Units in 1 Kilojoule.
What is the formula for British Thermal Unit to Kilojoule conversion?
The formula is: multiply by 1.05506. This means 1 BTU = 1.05506 kJ.
Is a British Thermal Unit bigger than a Kilojoule?
No. One British Thermal Unit is smaller than one Kilojoule because 1 BTU equals 1.05506 kJ, which is greater than 1.
When do you need to convert between British Thermal Units and Kilojoules?
A metric unit of energy equal to exactly 1,000 joules. British Thermal Unit and Kilojoule are both energy units, so conversion comes up whenever one source of information uses one unit and another uses the other — a classic cross-reference challenge in engineering, trade, travel, and everyday life.