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 calorie (thermochemical)?
The thermochemical calorie is a unit of energy equal to approximately 4.184 joules. It is used in chemistry and physics to express small heat quantities, particularly in thermochemical experiments.
Real-world uses
The thermochemical calorie (4.184 J) is used in chemistry for expressing heats of reaction, specific heat capacities of substances, and calorimetry experiments. It appears in older scientific literature and some chemistry textbooks, particularly in calorimetric calculations.
History
The calorie was first defined by Nicolas Clément in 1824 as the heat needed to raise 1 gram of water by 1°C. The thermochemical calorie (exactly 4.184 J) was later standardized for precise scientific use, distinguishing it from other calorie definitions.
Common mistakes
Confusing the small calorie (cal, 4.184 J) with the large Calorie/kilocalorie (Cal/kcal, 4,184 J) used in food labelling. Also, several slightly different definitions of the calorie exist (thermochemical, 15°C, IT), which differ by fractions of a percent.
When is this conversion used?
Converting between therm (US) and calorie (thermochemical) 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.
Worked examples
1 therm (US) = 25,216,539.19694072 calorie (thermochemical)
1 calorie (thermochemical) = 4.184 joule
How to convert therm (US) to calorie (thermochemical)
To convert therm (US) to calorie (thermochemical), multiply the value by 25,216,539.19694072.
To convert calorie (thermochemical) back to therm (US), multiply by 3.965651e-08.
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 calorie (thermochemical)
| therm (US) | calorie (thermochemical) |
|---|---|
| 0.1 | 2,521,653.91969407 |
| 0.5 | 12,608,269.59847036 |
| 1 | 25,216,539.19694072 |
| 2 | 50,433,078.39388145 |
| 5 | 126,082,695.98470363 |
| 10 | 252,165,391.96940726 |
| 25 | 630,413,479.92351818 |
| 50 | 1.260827e+09 |
| 100 | 2.521654e+09 |
| 250 | 6.304135e+09 |
| 500 | 1.260827e+10 |
| 1,000 | 2.521654e+10 |
Common values
| therm (US) | calorie (thermochemical) | |
|---|---|---|
| A food calorie (1 kcal) | 0.00003966 therm (US) | 1,000 calorie (thermochemical) |
| A AA battery | 0.00008872 therm (US) | 2,237.09369025 calorie (thermochemical) |
| Boiling a kettle | 0.00398082 therm (US) | 100,382.40917782 calorie (thermochemical) |
| Daily human diet (2000 kcal) | 0.07931302 therm (US) | 2,000,000 calorie (thermochemical) |
| 1 gallon of gasoline | 1.24883893 therm (US) | 31,491,395.79349904 calorie (thermochemical) |
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.