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Unit Conversion Factors

This page provides conversion tables for common engineering units.

Contents

Unit Conversion Tables

In the following tables, a number in bold and blue indicates an exact conversion value.

Length

A table of conversion factors between common length units is provided below:

in ft yd mi NM m mm km
1 in (inch) = 1 0.08333333 0.02777778 1.578283 E-5 1.371490 E-5 0.0254 25.4 2.54 E-5
1 ft (foot) = 12 1 0.3333333 1.893939 E-4 1.645788 E-4 0.3048 304.8 3.048 E-4
1 yd (yard) = 36 3 1 5.681818 E-4 4.937365 E-4 0.9144 914.4 9.144 E-4
1 mi (mile) = 63360 5280 1760 1 0.8689762 1609.344 1.609344 E6 1.609344
1 NM (nautical mile) = 72913.38588 6076.11549 2025.37183 1.150779 1 1852.000 1.852000 E6 1.852000
1 m (meter) = 39.37008 3.280840 1.093613 6.213712 E-4 5.399568 E-4 1 1000 0.001
1 mm (millimeter) = 0.03937008 3.280840 E-3 1.093613 E-3 6.213712 E-7 5.399568 E-7 0.001 1 1 E-6
1 km (kilometer) = 39370.08 3280.840 1093.613 0.6213712 0.5399568 1000 1 E6 1

Area

A table of conversion factors between common area units is provided below:

in2 ft2 mi2 acre m2 cm2 mm2
1 in2 (inch2) = 1 6.944444 E-3 2.490977 E-10 1.594225 E-7 6.4516 E-4 6.4516 645.16
1 ft2 (foot2) = 144 1 3.587006 E-8 2.295684 E-5 0.09290304 929.0304 9.290304 E4
1 mi2 (mile2) = 4.0144896 E9 2.78784 E7 1 640 2.589988 E6 2.589988 E10 2.589988 E12
1 acre = 6.27264 E6 43560 1.5625 E-3 1 4.046856 E3 4.046856 E7 4.046856 E9
1 m2 (meter2) = 1.550003 E3 10.76391 3.861022 E-7 2.471054 E-4 1 1 E4 1 E6
1 cm2 (centimeter2) = 0.1550003 1.076391 E-3 3.861022 E-11 2.471054 E-8 0.0001 1 100
1 mm2 (millimeter2) = 1.550003 E-3 1.076391 E-5 3.861022 E-13 2.471054 E-10 1 E-6 0.01 1

Volume

A table of conversion factors between common volume units is provided below:

in3 ft3 gal pint cm3 m3 L
1 in3 (cubic inch) = 1 5.787037 E-4 4.329004 E-3 0.03463203 16.387064 1.638706 E-5 0.01638706
1 ft3 (cubic foot) = 1728 1 7.480519 59.84416 28316.85 0.02831685 28.31685
1 gal (gallon) = 231 0.1336806 1 8 3785.412 3.785412 E-3 3.785412
1 pint = 28.875 0.01671007 0.125 1 473.1765 4.731765 E-4 0.4731765
1 cm3 (cubic centimeter) (CC) = 0.06102374 3.531467 E-5 2.641720 E-4 0.0021134 1 1 E-6 0.001
1 m3 (cubic meter) = 61023.74 35.31467 264.1720 2113.376 1 E6 1 1000
1 L (liter) = 61.02374 0.03531467 0.2641720 2.113376 1000 0.001 1

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Mass

A table of conversion factors between common mass units is provided below:

lbm slug oz short ton long ton kg tonne
1 lbm (pound-mass) = 1 0.03108095 16 0.0005 4.464286 E-4 0.45359237 4.5359237 E-4
1 slug = 32.17405 1 514.7848 0.01608702 0.01436341 14.59390 0.01459390
1 oz (avoirdupois ounce) = 0.0625 1.942559 E-3 1 3.125 E-5 2.790179 E-5 0.02834952 2.834952 E-5
1 ton (short) = 2000 62.16190 32000 1 0.8928571 907.18474 0.90718474
1 ton (long) = 2240 69.62133 35840 1.12 1 1016.047 1.016047
1 kg (kilogram) = 2.204623 0.06852177 35.27396 1.102311 E-3 9.842065 E-4 1 0.001
1 tonne (metric ton) = 2204.623 68.52177 3.527396 E4 1.102311 0.9842065 1000 1
  • NOTE: The Avoirdupois ounce is what is typically used in engineering work, as opposed to the Troy ounce (which is used for weighing gold and silver).

Density

A table of conversion factors between common density units is provided below:

lbm/in3 lbm/ft3 slug/ft3 g/cm3 kg/m3
1 lbm/in3 = 1 1728 53.70788 27.67990 27679.90
1 lbm/ft3 = 5.787037 E-4 1 0.03108095 0.01601846 16.01846
1 slug/ft3 = 0.01861924 32.17405 1 0.5153788 515.3788
1 g/cm3 = 0.03612729 62.42796 1.940320 1 1000
1 kg/m3 = 3.612729 E-5 0.06242796 1.940320 E-3 0.001 1

Force

A table of conversion factors between common force units is provided below:

lbf kip N gf kgf dyne
1 lbf (pound-force) = 1 0.001 4.448222 453.5924 0.4535924 4.448222 E5
1 kip (1000 lbf) = 1000 1 4.448222 E3 4.535924 E5 453.5924 4.448222 E8
1 N (Newton) = 0.2248089 2.248089 E-4 1 101.9716 0.1019716 1 E5
1 gf (gram-force) = 2.204623 E-3 2.204623 E-6 9.80665 E-3 1 0.001 980.665
1 kgf (kilogram-force) = 2.204623 2.204623 E-3 9.80665 1000 1 9.80665 E5
1 dyne = 2.248089 E-6 2.248089 E-9 1 E-5 1.019716 E-3 1.019716 E-6 1
  • NOTE: A kilopond (kp) is another term for kilogram-force (kgf).

Moment & Torque

A table of conversion factors between common units of moment and torque is provided below:

in•lbf ft•lbf N•m kgf•m dyne•cm
1 in•lbf (inch-pound) = 1 0.08333333 0.1129848 0.01152125 1.129848 E6
1 ft•lbf (foot-pound) = 12 1 1.355818 0.1382550 1.355818 E7
1 N•m (Newton-meter) = 8.850746 0.7375621 1 0.1019716 1 E7
1 kgf•m (kilogram-force-meter) = 86.79617 7.233014 9.80665 1 9.80665 E7
1 dyne•cm (dyne-centimeter) = 8.850746 E-7 7.375621 E-8 1 E-7 1.019716 E-8 1

Pressure & Stress

A table of conversion factors between common units of pressure and stress is provided below:

psi ksi psf Pa kPa MPa
1 psi (lbf/in2) = 1 0.001 144 6894.757 6.894757 6.894757 E-3
1 ksi (1000 psi) = 1000 1 144000 6.894757 E6 6894.757 6.894757
1 psf (lbf/ft2) = 6.944444 E-3 6.944444 E-6 1 47.88026 0.04788026 4.788026 E-5
1 Pa (Pascal) = 1.450377 E-4 1.450377 E-7 0.02088543 1 0.001 1 E-6
1 kPa (kilopascal) = 0.1450377 1.450377 E-4 20.88543 1000 1 0.001
1 MPa (megapascal) = 145.0377 0.1450377 20885.43 1 E6 1000 1
  • NOTE: A Pascal is a derived unit equal to 1 N/m2.

Fluid Pressure

A table of conversion factors between common fluid pressure units is provided below:

psi psf kPa atm bar in Hg mm Hg in H2O mm H2O
1 psi (lbf/in2) = 1 144 6.894757 0.06804596 0.06894757 2.036020 51.71492 27.67990 703.0696
1 psf (lbf/ft2) = 6.944444 E-3 1 0.04788026 4.725414 E-4 4.788026 E-4 0.01413903 0.3591314 0.1922216 4.882428
1 kPa (kilopascal) = 0.1450377 20.88543 1 9.869233 E-3 0.01 0.2952998 7.500615 4.014631 101.9716
1 atm (atmosphere) = 14.69595 2116.217 101.325 1 1.01325 29.92125 759.9998 406.7825 10332.27
1 bar = 14.50377 2088.543 100 0.9869233 1 29.52998 750.0615 401.4631 10197.16
1 in Hg (inches of mercury) = 0.4911542 70.72620 3.386389 0.03342106 0.03386389 1 25.4 13.59510 345.3156
1 mm Hg (mm of mercury) = 0.01933678 2.784496 0.1333224 1.315790 E-3 1.333224 E-3 0.03937008 1 0.5352402 13.59510
1 in H2O (inches of water) = 0.03612729 5.202330 0.2490889 2.458316 E-3 2.490889 E-3 0.07355591 1.868320 1 25.4
1 mm H2O (mm of water) = 1.422334 E-3 0.2048161 9.80665 E-3 9.678411 E-5 9.80665 E-5 2.895902 E-3 0.07355591 1.868320 1

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Velocity (Linear)

A table of conversion factors between common velocity units is provided below:

ft/s ft/min mph m/s kph knot mach
1 ft/s = 1 60 0.6818182 0.3048 1.09728 0.5924838 8.886297 E-4
1 ft/min = 0.01666667 1 0.01136364 0.00508 0.018288 9.874730 E-3 1.481050 E-5
1 mph (miles/hour) = 1.466667 88 1 0.44704 1.609344 0.8689762 1.303324 E-3
1 m/s = 3.280840 196.8504 2.236936 1 3.6 1.943844 2.915452 E-3
1 kph (kilometers/hour) = 0.9113444 54.68066 0.6213712 0.2777778 1 0.5399568 8.098477 E-4
1 knot = 1.687810 101.2686 1.150779 0.5144444 1.852 1 1.499838 E-3
1 mach = 1125.328 67519.69 767.2691 343 1234.800 666.7387 1

NOTES:

  • A knot is a nautical mile per hour.
  • Mach 1 is equal to the speed of sound, which is 343 m/s in dry air at 20 °C (68 °F). The speed of sound varies depending on the medium (substance) the sound is travelling through and the temperature.

Acceleration (Linear)

A table of conversion factors between common acceleration units is provided below:

g in/s2 ft/s2 m/s2
1 g = 1 386.0886 32.17405 9.80665
1 in/s2 = 2.590079 E-3 1 0.08333333 0.0254
1 ft/s2 = 0.03108095 12 1 0.3048
1 m/s2 = 0.1019716 39.37008 3.280840 1
  • NOTE: 1 g is the acceleration due to gravity.

Angular Velocity

A table of conversion factors between common angular velocity units is provided below:

rad/sec deg/sec rev/sec rpm (rev/min)
1 rad/sec = 1
1 deg/sec =
1 1/360 1/6
1 rev/sec = 2π 360 1 60
1 rpm (rev/min) =
6 1/60 1

Volumetric Flow Rate

A table of conversion factors between common volumetric flow rate units is provided below:

in3/s ft3/s ft3/min gpm m3/s L/s
1 in3/s = 1 5.787037 E-4 0.03472222 0.2597402 1.638706 E-5 0.01638706
1 ft3/s = 1728 1 60 448.8311 0.02831685 28.31685
1 ft3/min = 28.8 0.01666667 1 7.480519 4.719474 E-4 0.4719474
1 gpm (gal/min) (US) = 3.850000 2.228009 E-3 0.1336806 1 6.309020 E-5 0.06309020
1 m3/s = 61023.74 35.31467 2118.880 15850.32 1 1000
1 L/s = 61.02374 0.03531467 2.118880 15.85032 0.001 1

Energy & Work

A table of conversion factors between common units of energy and work is provided below:

ft•lbf Btu J (N•m) kJ kW•hr kcal eV
1 ft•lbf (foot-pound) = 1 1.285067 E-3 1.355818 1.355881 E-3 3.766161 E-7 3.238316 E-4 8.46235 E18
1 Btu (British thermal unit) = 778.1693 1 1055.056 1.055056 2.930711 E-4 0.2519958 6.58514 E21
1 J (Joule) (N•m) = 0.7375621 9.478171 E-4 1 0.001 2.777778 E-7 2.388459 E-4 6.24151 E18
1 kJ (kilojoule) = 737.5621 0.9478171 1000 1 2.777778 E-4 0.2388459 6.24151 E21
1 kW•hr (kilowatt-hour) = 2.655224 E6 3412.142 3.6 E6 3600 1 859.8452 2.24694 E25
1 kcal (kilocalorie) = 3088.025 3.968321 4186.8 4.1868 1.163 E-3 1 2.61320 E22
1 eV (electron volt) = 1.18170 E-19 1.51857 E-22 1.60218 E-19 1.60218 E-22 4.45048 E-26 3.82673 E-23 1
  • NOTE: The units of Joule and N•m are equivalent and are both commonly used to express quantities of energy and work.

Power

A table of conversion factors between common power units is provided below:

ft•lbf/s ft•lbf/min hp kW Btu/s Btu/min Btu/hr
1 ft•lbf/s = 1 60 1.818182 E-3 1.355818 E-3 1.285067 E-3 0.0771040 4.626243
1 ft•lbf/min = 0.01666667 1 3.030303 E-5 2.259697 E-5 2.141779 E-5 1.285067 E-3 0.0771040
1 hp (horsepower) = 550 33000 1 0.7456999 0.7067871 42.40723 2544.434
1 kW (kilowatt) = 737.5621 44253.73 1.341022 1 0.9478171 56.86903 3412.142
1 Btu/s = 778.1693 46690.16 1.414853 1.055056 1 60 3600
1 Btu/min = 12.96949 778.1693 0.02358089 0.01758426 0.01666667 1 60
1 Btu/hr = 0.2161581 12.96949 3.930148 E-4 2.930711 E-4 2.777778 E-4 0.01666667 1
  • NOTE: A refrigeration ton is an important unit in HVAC that is not given in the table above. 1 refrigeration ton = 200 Btu/min = 12,000 Btu/hr = 3.516853 kW

Stress Intensity

Stress intensity is an important quantity in fracture mechanics. Conversions between the most common units are given in the table below:

ksi√in MPa√m
1 ksi√in = 1 1.098843
1 MPa√m = 0.9100477 1

Temperature

A table of conversions between common temperature units is provided below:

T ΔT
°C to °F (Celsius to Fahrenheit):
°F to °R (Fahrenheit to Rankine):
°C to K (Celsius to Kelvin):


References

  1. "Guide for the Use of the International System of Units (SI)," National Institute of Standards and Technology (NIST), 2008.
  2. Machinery's Handbook, 27th Ed., Industrial Press Inc., 2004.