Foot-pounds (ft-lbf) to US Therms (thm) conversion

1 ft-lbf = 1.285374e-8 thmthm → ft-lbf
Formula
1 ft-lbf = 1.285374e-8 thm

Understanding Foot-pounds to US Therms Conversion

A foot-pound (ft-lbf) is the imperial unit of mechanical work, about 1.356 joules. A US therm (thm) is a unit of heat energy equal to 100,000 British thermal units, roughly 1.0548 × 10⁸ joules, used chiefly to bill natural gas in the United States. Converting foot-pounds to US therms relates mechanical work to the large thermal-energy units of the gas utility industry, useful for energy accounting and cross-domain comparisons.

Conversion Formula

1 ft-lbf=1.28537×10−8 thm1\ \text{ft-lbf} = 1.28537 \times 10⁻⁸\ \text{thm}

To convert Foot-pounds to US Therms, multiply by this factor:

thm=ft-lbf×1.285374×10−8\text{thm} = \text{ft-lbf} \times 1.285374 \times 10⁻⁸

Step-by-Step Example

Convert 25 Foot-pounds to US Therms.

thm=25×1.285374×10−8=3.21344×10−7 thm\text{thm} = 25 \times 1.285374 \times 10⁻⁸ = 3.21344 \times 10⁻⁷\ \text{thm}

How to Convert Foot-pounds to US Therms

Relate foot-pounds of work to natural-gas therms in one multiplication.

  1. Record the value: Note the energy in foot-pounds (ft-lbf).
  2. Multiply by the factor: Multiply by 1.285374 × 10⁻⁸, the US therms per foot-pound.
  3. Use scientific notation: The very small result is clearest as a power of ten.
  4. Worked result: For 25 ft-lbf, 25 × 1.285374 × 10⁻⁸ = 3.21344 × 10⁻⁷ thm.

Foot-pounds to US Therms conversion table

Foot-pounds (ft-lbf)US Therms (thm)
00
11.285374e-8
22.570749e-8
33.856123e-8
45.141497e-8
56.426871e-8
67.712246e-8
78.99762e-8
81.028299e-7
91.156837e-7
101.285374e-7
151.928061e-7
202.570749e-7
253.213436e-7
303.856123e-7
405.141497e-7
506.426871e-7
607.712246e-7
708.99762e-7
800.000001028299
900.000001156837
1000.000001285374
1500.000001928061
2000.000002570749
2500.000003213436
3000.000003856123
4000.000005141497
5000.000006426871
6000.000007712246
7000.00000899762
8000.00001028299
9000.00001156837
10000.00001285374
20000.00002570749
30000.00003856123
40000.00005141497
50000.00006426871
100000.0001285374
250000.0003213436
500000.0006426871
1000000.001285374
2500000.003213436
5000000.006426871
10000000.01285374

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:

1 ft-lbf=1.35582 J1\ \text{ft-lbf} = 1.35582\ \text{J}

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.

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:

1 thm=1.05480×108 J1\ \text{thm} = 1.05480 \times 10⁸\ \text{J}

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.

Frequently Asked Questions

How many US therms are in a foot-pound?

One foot-pound equals about 1.285374 × 10⁻⁸ US therms. It takes tens of millions of foot-pounds to reach a single therm.

What is a US therm?

A US therm is 100,000 British thermal units, about 1.0548 × 10⁸ joules. It is the standard unit for billing natural gas in the United States.

How do I convert foot-pounds to US therms?

Multiply the foot-pound value by 1.285374 × 10⁻⁸. For example, 10⁷ ft-lbf equals about 0.1285 thm.

How many foot-pounds equal one US therm?

About 77,798,350 foot-pounds equal one US therm, the reverse of this conversion.

Why convert mechanical work into therms?

It lets mechanical energy be compared with the natural-gas energy that appears on utility bills, aiding whole-system energy accounting.

People also convert

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Complete Foot-pounds conversion table

ft-lbf
UnitResult
Watt-seconds (Ws)1.355818 Ws
Watt-minutes (Wm)0.02259697 Wm
Watt-hours (Wh)0.0003766161 Wh
Milliwatt-hours (mWh)0.3766161 mWh
Kilowatt-hours (kWh)3.766161e-7 kWh
Megawatt-hours (MWh)3.766161e-10 MWh
Gigawatt-hours (GWh)3.766161e-13 GWh
Joules (J)1.355818 J
Kilojoules (kJ)0.001355818 kJ
Megajoules (MJ)0.000001355818 MJ
Gigajoules (GJ)1.355818e-9 GJ
British Thermal Units (IT) (BTU)0.001285067 BTU
US Therms (thm)1.285374e-8 thm
Electronvolts (eV)8462350000000000000 eV
Ergs (erg)13558180 erg
Tonnes of TNT (t-tnt)3.240483e-10 t-tnt
calories (cal)0.3240483 cal
Kilocalories (kcal)0.0003240483 kcal

Energy conversions