Understanding US Therms to Foot-pounds Conversion
The US therm (thm) is a natural-gas energy unit equal to 100,000 BTU, used to bill gas consumption. The foot-pound (ft-lbf) is an imperial unit of energy or work equal to the effort of moving one pound-force through a distance of one foot, about 1.356 joules. Converting therms to foot-pounds expresses natural-gas heat energy in mechanical work terms, which is useful for comparing thermal and mechanical energy in engineering.
Conversion Formula
To convert US Therms to Foot-pounds, multiply by this factor:
Step-by-Step Example
Convert 25 US Therms to Foot-pounds.
How to Convert US Therms to Foot-pounds
Express natural-gas therm energy as mechanical foot-pounds in one step.
- Note your therm value: Record the energy amount in US therms.
- Multiply by the factor: Multiply by 77,798,350 foot-pounds per therm.
- Read the total: The result is the equivalent mechanical work in foot-pounds.
- Worked result: 25 therms × 77,798,350 = 1.94496 × 10⁹ foot-pounds.
US Therms to Foot-pounds conversion table
| US Therms (thm) | Foot-pounds (ft-lbf) |
|---|---|
| 0 | 0 |
| 1 | 77798350 |
| 2 | 155596700 |
| 3 | 233395100 |
| 4 | 311193400 |
| 5 | 388991800 |
| 6 | 466790100 |
| 7 | 544588500 |
| 8 | 622386800 |
| 9 | 700185200 |
| 10 | 777983500 |
| 15 | 1166975000 |
| 20 | 1555967000 |
| 25 | 1944959000 |
| 30 | 2333951000 |
| 40 | 3111934000 |
| 50 | 3889918000 |
| 60 | 4667901000 |
| 70 | 5445885000 |
| 80 | 6223868000 |
| 90 | 7001852000 |
| 100 | 7779835000 |
| 150 | 11669750000 |
| 200 | 15559670000 |
| 250 | 19449590000 |
| 300 | 23339510000 |
| 400 | 31119340000 |
| 500 | 38899180000 |
| 600 | 46679010000 |
| 700 | 54458850000 |
| 800 | 62238680000 |
| 900 | 70018520000 |
| 1000 | 77798350000 |
| 2000 | 155596700000 |
| 3000 | 233395100000 |
| 4000 | 311193400000 |
| 5000 | 388991800000 |
| 10000 | 777983500000 |
| 25000 | 1944959000000 |
| 50000 | 3889918000000 |
| 100000 | 7779835000000 |
| 250000 | 19449590000000 |
| 500000 | 38899180000000 |
| 1000000 | 77798350000000 |
What is the US Therm?
The US therm is a unit of heat energy used primarily in the natural gas industry to measure and bill the energy content of gas supplied to homes and businesses in the United States.
Definition
The US therm is defined as 100,000 British thermal units (BTU) based on the 59 °F (15 °C) BTU:
More precisely, the US therm equals exactly 105,480,400 joules (about 105.48 MJ). It should not be confused with the slightly larger UK therm, which is based on the International Table BTU and equals 105,505,585.257 J.
Origin and History
The therm entered use in the 20th century as gas utilities shifted from billing customers by volume to billing by delivered energy, since the heating value of natural gas varies with its composition. Combining "therm" (from the Greek thermē, heat) with a fixed BTU count gave a convenient billing unit roughly equal to the energy in 100 cubic feet of typical natural gas.
Law and Notable Facts
In the United States the therm is a legally recognized commercial unit for natural gas sales. Gas meters record volume in hundreds of cubic feet (ccf), which utilities multiply by a "therm factor" reflecting the gas's actual heat content to convert to therms for billing.
Real-World Examples and Conversions
- A typical US home uses roughly 500 to 1,000 therms of natural gas per year for heating, cooking, and hot water.
- 1 therm equals about 29.3 kilowatt-hours of energy.
- Burning 1 therm of natural gas releases approximately 105.5 MJ of heat, enough to run a 20 kW furnace at full output for about 88 minutes.
What is the Foot-pound?
The foot-pound (foot-pound-force) is a unit of energy or work in the imperial and US customary systems, representing mechanical work done against gravity or by a force.
Definition
One foot-pound is the work done when a force of one pound-force moves an object one foot in the direction of the force:
Precisely, 1 ft·lbf = 1.3558179483314004 J, derived from the standard pound-force (4.4482216152605 N) times the international foot (0.3048 m). It should not be confused with the pound-foot, the identical-magnitude unit conventionally reserved for torque.
Origin and History
The unit grew directly out of imperial mechanics, combining the foot and the pound-force, the everyday units of length and weight in Britain and America. It became a standard measure of work in engineering and firearms ballistics long before metric energy units gained ground in the English-speaking world.
Law and Notable Facts
The foot-pound remains widely used in the United States, especially for muzzle energy of firearms and for engine and tool work ratings. Multiplying foot-pounds per unit time gives power; 550 ft·lbf per second defines one mechanical horsepower.
Real-World Examples and Conversions
- 1 foot-pound is about 1.356 joules.
- A .22 Long Rifle bullet typically leaves the muzzle with roughly 100 to 140 ft·lbf of energy.
- Lifting a 50-pound weight by 4 feet requires 200 ft·lbf, or about 271 joules of work.
Frequently Asked Questions
How many foot-pounds are in one US therm?
One US therm equals about 77,798,350 foot-pounds, since a foot-pound is a small mechanical-energy unit of roughly 1.356 joules.
How do I convert US therms to foot-pounds?
Multiply the therm value by 77,798,350. The result runs into the tens of millions of foot-pounds per therm.
How many therms equal one foot-pound?
One foot-pound is about 1.285374 × 10⁻⁸ US therms, a very small fraction.
What is a foot-pound?
The foot-pound is an imperial unit of energy or work equal to moving one pound-force through one foot, used in mechanics and engineering.
Why convert thermal therms into mechanical foot-pounds?
It lets engineers compare the heat energy in natural gas directly against mechanical work, since energy is conserved across thermal and mechanical forms.
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Complete US Therms conversion table
| Unit | Result |
|---|---|
| Watt-seconds (Ws) | 105480400 Ws |
| Watt-minutes (Wm) | 1758007 Wm |
| Watt-hours (Wh) | 29300.11 Wh |
| Milliwatt-hours (mWh) | 29300110 mWh |
| Kilowatt-hours (kWh) | 29.30011 kWh |
| Megawatt-hours (MWh) | 0.02930011 MWh |
| Gigawatt-hours (GWh) | 0.00002930011 GWh |
| Joules (J) | 105480400 J |
| Kilojoules (kJ) | 105480.4 kJ |
| Megajoules (MJ) | 105.4804 MJ |
| Gigajoules (GJ) | 0.1054804 GJ |
| British Thermal Units (IT) (BTU) | 99976.13 BTU |
| Electronvolts (eV) | 6.583569e+26 eV |
| Ergs (erg) | 1054804000000000 erg |
| Foot-pounds (ft-lbf) | 77798350 ft-lbf |
| Tonnes of TNT (t-tnt) | 0.02521042 t-tnt |
| calories (cal) | 25210420 cal |
| Kilocalories (kcal) | 25210.42 kcal |