What is therm (US)?
A US therm is a unit of energy equal to 100,000 BTU. It is used by gas utility companies in the United States as the standard billing unit for natural gas consumption.
Real-world uses
The therm is used in the United States and United Kingdom for natural gas billing. One therm equals 100,000 BTU (approximately 29.3 kWh). Residential gas bills in the US often list consumption in therms. It is also used in industrial gas metering and procurement contracts.
History
The therm was introduced as a practical unit for natural gas billing in the early 20th century, when gas supply companies needed a convenient large-scale energy unit for residential and commercial customers. It consolidated prior inconsistent measurement practices in the gas industry.
Common mistakes
Confusing the therm with the BTU—1 therm = 100,000 BTU. Also, the US therm and the UK therm differ slightly (the UK therm is based on 105.5 MJ, while the US therm is exactly 100,000 BTU ≈ 105.48 MJ). Not to be confused with the thermie (a metric unit of heat).
What is joule?
The joule is the SI base unit of energy. It is the standard unit for work, heat, and electrical energy in physics, engineering, and scientific measurement worldwide.
Real-world uses
The joule is the SI unit of energy used in physics, chemistry, and nutrition (food energy in some countries is labelled in kilojoules). Electrical energy, mechanical work, and heat transfer are all measured in joules. One joule is the energy to lift a small apple about 1 metre.
History
Named after James Prescott Joule, the English physicist who demonstrated the mechanical equivalent of heat in the 1840s, establishing that heat and mechanical work are interchangeable forms of energy. The joule was adopted as the SI energy unit in 1960.
Common mistakes
Confusing joules with watts—a joule is a unit of energy, while a watt is a unit of power (1 W = 1 J/s). Also, assuming "calorie" and "joule" are equivalent without conversion: 1 cal = 4.184 J.
When is this conversion used?
Converting between therm (US) and joule is common when working across metric and imperial systems, such as international trade, travel between countries with different measurement standards, or following instructions from a different region. Electricity bills use kilowatt-hours while physics calculations use joules. Converting between them is essential for energy audits, comparing appliance efficiency, and understanding power consumption.
Worked examples
1 therm (US) = 105,506,000 joule
1 joule = 1 joule
How to convert therm (US) to joule
To convert therm (US) to joule, multiply the value by 105,506,000.
To convert joule back to therm (US), multiply by 9.478134e-09.
Measurement standards
The joule is the SI derived unit of energy, defined as one kilogram-metre-squared per second-squared (kg·m²/s²). The kilowatt-hour, equal to exactly 3.6 megajoules, is accepted for use with the SI by the BIPM for practical electricity metering.
Did you know?
A single bolt of lightning releases roughly 1 to 5 gigajoules of energy, yet only a small fraction reaches the ground as electrical current. Most of the energy dissipates as light, heat, and the thunder shockwave.
Quick reference: therm (US) to joule
| therm (US) | joule |
|---|---|
| 0.1 | 10,550,600 |
| 0.5 | 52,753,000 |
| 1 | 105,506,000 |
| 2 | 211,012,000 |
| 5 | 527,530,000 |
| 10 | 1.055060e+09 |
| 25 | 2.637650e+09 |
| 50 | 5.275300e+09 |
| 100 | 1.055060e+10 |
| 250 | 2.637650e+10 |
| 500 | 5.275300e+10 |
| 1,000 | 1.055060e+11 |
Common values
| therm (US) | joule | |
|---|---|---|
| A food calorie (1 kcal) | 0.00003966 therm (US) | 4,184 joule |
| A AA battery | 0.00008872 therm (US) | 9,360 joule |
| Boiling a kettle | 0.00398082 therm (US) | 420,000 joule |
| Daily human diet (2000 kcal) | 0.07931302 therm (US) | 8,368,000 joule |
| 1 gallon of gasoline | 1.24883893 therm (US) | 131,760,000 joule |
Available Energy units
More therm (US) conversions
- Convert therm (US) to joule
- Convert therm (US) to kilojoule
- Convert therm (US) to kilowatt hour
- Convert therm (US) to calorie (thermochemical)
- Convert therm (US) to kilocalorie (dietary)
- Convert therm (US) to watt hour
- Convert therm (US) to megajoule
- Convert therm (US) to electronvolt
- Convert therm (US) to British thermal unit
Assumption: calorie means thermochemical calorie, and therm means US therm.