British Thermal Unit Conversion Tool - Convert BTU to Any Unit
Convert British Thermal Units to Other Units
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Convert Other Units to British Thermal Units
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Related Energy / Work / Heat Units
Joule (J)
SI unit of energy - work done by a force of one newton moving one meter
Calorie (cal)
Energy needed to raise 1g of water by 1°C - 4.184 joules
Kilowatt-hour (kWh)
Energy consumed by a 1kW device in one hour - 3.6 million joules
Foot-pound (ft·lbf)
Imperial unit of energy - approximately 1.356 joules
British Thermal Unit Conversion Table
This comprehensive BTU conversion table shows how various units relate to British thermal units. Use this reference for quick conversions between BTU and other common energy units.
| Conversion | To Unit | Multiplier |
|---|---|---|
| BTU to joules | Joules | 1055.06 |
| BTU to kilojoules | Kilojoules | 1.05506 |
| BTU to calories | Calories | 252.164 |
| BTU to kilocalories | Kilocalories | 0.252164 |
| BTU to electronvolts | Electronvolts | 6.585e+21 |
| BTU to foot-pounds | Foot-pounds | 778.169 |
| BTU to ergs | Ergs | 1.055e+10 |
| BTU to therms | Therms | 0.00001 |
| BTU to tons of TNT | Tons of TNT | 0.000252 |
| BTU to watt-hours | Watt-hours | 0.293071 |
| BTU to kilowatt-hours | Kilowatt-hours | 0.000293071 |
| BTU to megawatt-hours | Megawatt-hours | 2.93071e-7 |
This BTU conversion reference table provides accurate conversion factors for both SI and imperial units. All values are based on internationally recognized standards for maximum precision in scientific and engineering applications.
What is a British Thermal Unit?
The British thermal unit (symbol: BTU) is a traditional unit of heat defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. It is commonly used in the United States for measuring heating and cooling systems, as well as in energy industries. Our BTU conversion tool helps you easily convert between BTU and other energy units. For example, 1 BTU equals approximately 1055 joules or 0.293 watt-hours.
The BTU is not part of the International System of Units (SI), but it remains widely used in certain applications, particularly in the HVAC (heating, ventilation, and air conditioning) industry. There are different definitions of BTU based on different water temperatures, with the most common being the International Table BTU (BTUIT) which is approximately 1055.05585 joules.
What is the SI of British Thermal Unit?
The British thermal unit is not an SI unit. The joule (J) is the SI unit for energy, work, and heat. However, the BTU is still widely used in non-SI contexts, particularly in the United States. All other energy units in the metric system are derived from the joule, making it essential for SI units conversion:
- Kilojoule (kJ) = 1,000 joules
- Calorie (cal) = 4.184 joules
- Watt-hour (Wh) = 3,600 joules
- Kilowatt-hour (kWh) = 3.6 million joules
- Electronvolt (eV) = 1.60218e-19 joules
What are British Thermal Units Used For?
British thermal units are used in a wide range of applications, particularly in the United States. As a traditional unit for measuring heat energy, BTUs provide a standard for HVAC systems, energy billing, and industrial applications:
Heating & Cooling Systems
Air conditioner capacity is often measured in BTUs per hour (BTU/h). For example, a typical residential air conditioner might have a cooling capacity of 12,000 BTU/h (which is equivalent to 1 ton of refrigeration).
Energy Billing
Natural gas and heating oil consumption is often billed based on BTU content. For example, natural gas utilities may charge per therm (100,000 BTU) or per CCF (100 cubic feet, which contains approximately 103,000 BTU).
Food Industry
The energy content of food can be expressed in BTUs, though calories or joules are more common. For example, a typical candy bar contains about 250 food calories, which is equivalent to approximately 1,000 BTU.
Industrial Applications
Combustion efficiency of fuels, boiler output, and industrial process heating are often measured in BTUs. For example, a furnace might be rated at 100,000 BTU/h input capacity.
Etymology and History
The British thermal unit was defined in the 19th century as part of the British system of units. It was originally defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. Different definitions existed based on the specific temperature of water, leading to slight variations:
The International Table BTU (BTUIT) is defined as exactly 1055.05585262 joules. This definition was established to provide a precise conversion factor between BTU and joules. The BTU has been largely replaced by SI units in scientific contexts, but it remains common in commercial and domestic applications in the United States, particularly in the HVAC industry. This evolution reflects the advancement of measurement science and the global adoption of the metric system.
Frequently Asked Questions
Why is the BTU still used in the United States?
The BTU remains widely used in the United States due to historical reasons and established industry standards. The HVAC (heating, ventilation, and air conditioning) industry in particular has long used BTU ratings for equipment capacity. Changing to SI units would require significant retooling of industry practices and consumer education. However, for international scientific work, BTU is converted to joules using our BTU conversion tool.
How accurate is the BTU definition?
The current definition of the International Table BTU is extremely accurate, defined as exactly 1055.05585262 joules. This precise definition allows for consistent conversions between BTU and SI units. However, there are slight variations in BTU definitions (such as the 59°F BTU and the 60°F BTU) that differ by less than 0.1%, which is usually negligible for most applications.
What's the difference between BTU and BTU/h?
BTU measures energy (like joules), while BTU/h measures power (energy per unit time, like watts). BTU/h is commonly used to describe the rate of heat transfer, such as the cooling capacity of an air conditioner. For example, a 12,000 BTU/h air conditioner removes 12,000 BTU of heat per hour, which is equivalent to 3.517 kilowatts.
How do I convert BTU to other units?
Use our BTU conversion calculators above, or multiply by the appropriate conversion factor. For example, to convert BTU to joules, multiply by 1055.06; to convert BTU to kilowatt-hours, multiply by 0.000293. For detailed instructions on converting BTU to joules, visit our BTU to joules converter. Our tool also handles conversions to imperial units like calories and foot-pounds.
What are common uses for BTU conversion?
BTU conversion is essential in HVAC (selecting appropriate heating/cooling equipment), energy billing (understanding utility costs), industrial processes (calculating fuel efficiency), and comparing energy content of different fuels. Whether determining the size of an air conditioner for your home or calculating the energy efficiency of a furnace, our BTU converter tool simplifies these everyday tasks.
How does BTU conversion differ from other energy units?
As a non-SI unit, BTU requires specific conversion factors to translate to SI units like joules. The conversion factor is precisely defined (1 BTU = 1055.05585262 J), making conversions straightforward. This differs from some other non-SI units that may have less precise or more complex conversion relationships. Our BTU conversion tool handles all these relationships automatically.
Can I convert very small or very large BTU measurements?
Yes, our BTU converter handles both extremely small and large measurements with precision. For small values, you can convert milli-BTU or micro-BTU to joules. For large values, you can convert million BTU (MMBTU) to kilowatt-hours or therms. Our smart rounding feature ensures readable results for all scales, making it suitable for everything from residential HVAC calculations to industrial energy assessments.
Is your BTU conversion tool free to use?
Yes, our BTU conversion calculator is completely free with no registration required. Simply enter your value, select your target unit, and get instant, accurate results. We believe precise energy conversion should be accessible to everyone, from homeowners calculating heating needs to engineers working on complex energy systems.