British thermal unit.
BTU to US therms Converter — BTU to therm
Convert BTU (BTU) to US therm (therm) using the exact conversion factor (1 btu = 0.0000100024 us therm). See the formula, worked examples, conversion table, history, and common uses.
BTU to US therms converter
Converter
Engineering Converter
Convert common stress, force, torque, power, and energy units used in engineering.
Context values
Some unit families need one extra value for a physically accurate result.
US therm used for natural gas energy.
Result = input x 1055.055853 / 1.054804e+8.
Energy units are compatible.
Reserved above the conversion cards and below the converter.
About Converting BTU to US therms
BTU and US therm both measure a quantity used in structural or mechanical engineering — commonly stress, pressure, force, torque, power, or energy — where converting between the unit conventions used in different regions, industries, or equipment specifications is a routine part of design work. BTU is most often used for air conditioner and furnace capacity ratings in the us.
Formula
us therms = btu × 0.0000100023876722
This factor comes from each unit's defined relationship to the category's base unit: 1 btu equals 1055.05585262 base units, and 1 us therm equals 105480400 base units, so dividing one by the other gives the direct btu-to-us therm factor of 0.0000100023876722.
Simple example
1 BTU × 0.00001000238767 = 0.0000100024 therm
1 btu = 0.0000100024 us therms.
Real-world example
100 BTU × 0.00001000238767 = 0.0010002388 therm
100 btu = 0.0010002388 us therms.
Conversion table
| BTU (BTU) | US therm (therm) |
|---|---|
| 1 BTU | 0.0000100024 therm |
| 10 BTU | 0.0001000239 therm |
| 50 BTU | 0.0005001194 therm |
| 100 BTU | 0.0010002388 therm |
| 500 BTU | 0.0050011938 therm |
| 1,000 BTU | 0.0100023877 therm |
Reverse conversion: US therm to BTU
0.0000100024 therm × 99976.12898 = 1.000001232 BTU
0.0000100024 us therms = 1.000001232 btu.
btu = us therms × 99976.1289775
For a page dedicated to this direction, see US therm to BTU.
Understanding the BTU
BTU (BTU) measures energy. A British thermal unit is defined as exactly 1,055.05585262 joules (the International Table BTU). It is classified as a US customary unit.
Where it's used: United States (HVAC, heating, and appliance energy ratings)
Uses of the BTU today
- Air conditioner and furnace capacity ratings in the US
- Water heater and appliance energy specifications
- US energy industry (natural gas is often billed via BTU content)
History of the BTU
The BTU originated in 19th-century steam engineering as the heat needed to raise one pound of water by one degree Fahrenheit, paralleling the calorie's metric definition. Several slightly different BTU values existed historically before the 'International Table' BTU was standardized at exactly 1,055.05585262 joules.
Historical origin. BTU was not the invention of a single named person; it developed through the process described above.
Understanding the US therm (therm)
US therm used for natural gas energy.
BTU — sources
- NIST Special Publication 811 — Documents the International Table BTU's exact joule equivalence.
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many us therms are in 1 btu?
1 btu equals 0.0000100024 us therms, using the exact defined conversion factor rather than an estimate.
How do I convert btu to us therm?
Multiply the btu value by 0.00001000238767. The converter above does this instantly to whatever precision you set.
How do I convert us therm back to btu?
Use the reverse factor: 1 us therm equals 99,976.12898 btu. You can also use the swap control in the converter above to flip the direction instantly.
What is a btu?
BTU (BTU) measures energy. A British thermal unit is defined as exactly 1,055.05585262 joules (the International Table BTU). It is classified as a US customary unit.
What is a us therm?
US therm (therm) is a unit of engineering.
Is the btu to us therm conversion exact?
Yes. A British thermal unit is defined as exactly 1,055.05585262 joules (the International Table BTU). That fixed definition is what the converter above uses, so any rounding you see is a display choice, not a limitation of the math.
Where is the btu still used today?
United States (HVAC, heating, and appliance energy ratings)
Why do engineering unit conventions vary so much by region and industry?
Pressure, force, and stress can be expressed in metric (pascal, newton), US customary (psi, pound-force), or older and industry-specific units (atmosphere, torr, kip) depending on the country, industry, and even the equipment manufacturer, which is why engineers routinely need to convert between them when working across specs from different sources.