English to SI Conversion Factors
This table gives conversion factors to convert various units to their SI equivalents. It will not be very useful for people who prefer to use cgs or English units although it can be used to convert from SI to those systems. 
Name To convert from  to  multiply by  divide by 
Acceleration  ft/sec^2  m/s^2  0.3048  3.2810 
Area  acre  m^2  4047  2.471E-04 
Area  ft^2  m^2  9.294E-02  10.7600 
Area  hectare  m^2  1.000E+04  1.000E-04 
Area  in^2  m^2  6.452E-04  1550 
Density  g/cm^3  kg/m^3  1000  1.000E-03 
Density  lbm/ft^3  kg/m^3  16.02  6.243E-02 
Density  lbm/in^3  kg/m^3  2.767E+04  3.614E-05 
Density  lb*s^2/in^4  kg/m^3  1.069E+07  9.357E-08 
Density  slug/ft^3  kg/m^3  515.40  1.940E-03 
Energy  BTU  1055  9.478E-04 
Energy  cal  4.1859  0.2389 
Energy  erg  1.000E-07  1.000E+07 
Energy  ev  1.602E-19  6.242E+18 
Energy  ft*lbf  1.3557  0.7376 
Energy  kiloton TNT  4.187E+12  2.388E-13 
Energy  kW*hr  3.600E+06  2.778E-07 
Energy  megaton TNT  4.187E+15  2.388E-16 
Force  dyne  1.000E-05  1.000E+05 
Force  lbf  4.4484  0.2248 
Force  ozf  0.2780  3.5968 
Heat capacity  BTU/lbm*°F  J/kg*°C  4188  2.388E-04 
Heat transfer coefficient  BTU/hr*ft^2*°F  W/m^2*°C  5.6786  0.1761 
Length  AU  1.496E+11  6.685E-12 
Length  ft  0.3048  3.2810 
Length  in  2.540E-02  39.3700 
Length  mile  1609  6.214E-04 
Length  Nautical mile  1853  5.397E-04 
Length  parsec  3.085E+16  3.241E-17 
Mass  amu  kg  1.661E-27  6.022E+26 
Mass  lbm  kg  0.4535  2.2050 
Mass  lb*s^2/in  kg  1200.00  5.711E-03 
Mass  slug  kg  14.59  6.853E-02 
Mass flow rate  lbm/hr  kg/s  1.260E-04  7937 
Mass flow rate  lbm/sec  kg/s  0.4535  2.2050 
Moment of inertia  ft*lb*s^2  kg*m^2  1.3557  0.7376 
Moment of inertia  in*lb*s^2  kg*m^2  0.1130  8.8510 
Moment of inertia  oz*in*s^2  kg*m^2  7.062E-03  141.60 
Power  BTU/hr  0.2931  3.4120 
Power  hp  745.71  1.341E-03 
Power  tons of refrigeration  3516  2.844E-04 
Pressure  bar  Pa  1.000E+05  1.000E-05 
Pressure  dyne/cm^2  Pa  0.1000  10.0000 
Pressure  in. mercury  Pa  3377  2.961E-04 
Pressure  in. water  Pa  248.82  4.019E-03 
Pressure  kgf/cm^2  Pa  9.807E+04  1.020E-05 
Pressure  lbf/ft^2  Pa  47.89  2.088E-02 
Pressure  lbf/in^2  Pa  6897  1.450E-04 
Pressure  mbar  Pa  100.00  1.000E-02 
Pressure  microns mercury  Pa  0.1333  7.501 
Pressure  mm mercury  Pa  133.3  7.501E-03 
Pressure  std atm  Pa  1.013E+05  9.869E-06 
Specific heat  BTU/lbm*°F  J/kg*°C  4186  2.389E-04 
Specific heat  cal/g*°C  J/kg*°C  4186  2.389E-04 
Temperature  °F  °C  0.5556  1.8000 
Thermal conductivity  BTU/hr*ft*°F  W/m*°C  1.7307  0.5778 
Thermal conductivity  BTU*in/hr*ft^2*°F  W/m*°C  0.1442  6.9340 
Thermal conductivity  cal/cm*s*°C  W/m*°C  418.60  2.389E-03 
Thermal conductivity  cal/ft*hr*°F  W/m*°C  6.867E-03  145.62 
Thermal diffusivity ft^2/day m^2/day 0.09290304 10.7639104
Time  day  8.640E+04  1.157E-05 
Time  sidereal year  3.156E+07  3.169E-08 
Torque  ft*lbf  N*m  1.3557  0.7376 
Torque  in*lbf  N*m  0.1130  8.8504 
Torque  in*ozf  N*m  7.062E-03  141.61 
Velocity  ft/min  m/s  5.079E-03  196.90 
Velocity  ft/s  m/s  0.3048  3.2810 
Velocity  km/hr  m/s  0.2778  3.6000 
Velocity  miles/hr  m/s  0.4470  2.2370 
Viscosity - absolute  centipose  N*s/m^2  1.000E-03  1000 
Viscosity - absolute  g/cm*s  N*s/m^2  0.1000  10 
Viscosity - absolute  lbf/ft^2*s  N*s/m^2  47.87  2.089E-02 
Viscosity - absolute  lbm/ft*s  N*s/m^2  1.4881  0.6720 
Viscosity - kinematic  centistoke  m^2/s  1.000E-06  1.000E+06 
Viscosity - kinematic  ft^2/sec  m^2/s  9.294E-02  10.7600 
Volume  ft^3  m^3  2.831E-02  35.3200 
Volume  in^3  m^3  1.639E-05  6.102E+04 
Volume  liters  m^3  1.000E-03  1000 
Volume  U.S. gallons  m^3  3.785E-03  264.20 
Volume flow rate  ft^3/min  m^3/s  4.719E-04  2119 
Volume flow rate  U.S. gallons/min  m^3/s  6.309E-05  1.585E+04 


 
LENGTH
1 statute mile = 1.609344 km 1 km = 0.6213712 statute mile
1 yd = 0.9144 m  1 m = 1.0936133 yd
1 ft = 0.304799 m 1 m = 3.280851 ft
1 in = 2.5399956 cm 1 cm  = 0.39370147 in
1 in = 25.399956 mm 1 mm = 0.03937014 in
AREA
1 mile2 = 2.589998 km2 1 km2 = 0.3861007 statute mile
1 acre = 0.4046873 ha 1 ha = 2.4710437 acres
1 acre = 4046.873 m2 1 m2 = 0.0002471 acres
1 yd2 = 0.8361274 m2 1 m2 = 1.19599 yd2
1 ft2 = 0.09290304 m2 1 m2 = 10.7639104 ft2
1 in2 = 645.16 mm2 1 mm2 = 0.0015500 in2
VOLUME
1 acre ft = 1233.489 m3 1 m3 = 0.0008107 acre ft
1 yd3 = 0.7645549 m3 1 m3 = 1.307951 yd3
100 board ft = 0.2359737 m3 1 m3 = 4.2377604 board ft
1 ft3 = 0.02831685 m3 1 m3 = 35.3147 ft3
1 in3 = 16387.06 mm3 1 mm3 = 0.000061 in3
1 in3 = 16.3871 cm3 1 cm3 = 0.061024 in3
1 barrel = 0.1589873 m3 1 m3 = 6.2898106 barrel
FLUID CAPACITY
1 gal (US) = 3.785412 L 1 L = 0.264172 gal (US)
1 qt (US) = 946.3529 mL 1 mL = 0.0010567 qt (US)
1 pt (US) = 473.1765 mL 1 mL = 0.0021134 pt (US)
1 fl oz (US) = 29.5735 mL 1 mL = 0.0338141 fl oz (US)
1 gal (US) = 0.003785412 m3 1 m3 = 264.1720373 gal (US)
1 barrel (US) = 158.98 L 1 L = 0.0062901 barrel (US)
1 gal (US) = 0.83333 gal (UK) (approx.) 1 L = 0.001 m3 (approx.)
PLANE ANGLE
1° (degree) = 0.01745329 rad 1 rad = 57.2957878° (degree)
1° (degree) = 17.45329 mrad 1 mrad = 0.0572958° (degree)
1’ (minute) = 290.8882 urad 1 urad = 0.0034377’ (minute)
1" (second) = 4.848137 urad 1 urad = 0.2062648" (second)
SPEED
1 ft/m = 0.3048 m/m 1 m/m = 3.2808399 ft/m
1 ft/m = 0.00508 m/s 1 m/s = 196.8503937 ft/m
1 ft/s = 0.3048 m/s 1 m/s = 3.2808399 ft/s
1mile/h = 1.609344 km/h 1 km/h = 0.6213712 mile/h
1mile/h = 0.44704 m/s 1 m/s = 2.2369363 mile/h
TEMPERATURE
°F = [ (°F - 32) /1.8 ] oC °C = (°C x 1.8 + 32 ) °F
Example:   60 °F = [ (60 - 32) /1.8] = 15.6 °C Example:   30 °C = (30 x 1.8 + 32 ) = 86°F
FLOW
1 ft3/s = 0.02831685 m3/s 1 m3/s = 35.3146625 ft3/s
1 ft3/min = 0.4719474 L/s 1 L/s = 2.1188802 ft3/min
1 gal/min = 0.0630902 L/s 1 L/s = 15.8503222 gal/min
1gal/min = 0.0038 m3/min 1 m3/min = 263.1578947 gal/min
1 gal/hour = 1.0515 mL/s 1 mL/s = 0.9510223 gal/hour
1 million gal/d = 43.8126 L/s 1 L/s = 0.0228245 million gal/d
1 acre ft/s = 1233.49 m3/s 1 m3/s = 0.0008107 acre ft/s
MASS (WEIGHT)
1 ton (short) = 0.907185 metric ton 1 metric ton = 1.102311 ton (short)
1 ton (short) = 907.1847 kg 1 kg = 0.0011023 ton (short)
1 ton (long) = 1016.04706 kg 1 kg = 0.0009842 ton (long)
1 lb = 0.4535924 kg 1 kg = 2.2046225 lb
1 oz = 28.34952 g 1 g = 0.035274 oz
Note: 1 long ton = 1.12 short ton = 2240 lb
MASS PER UNIT AREA
1 lb/ft2 = 4.882428 kg/m2 1 kg/m2 = 0.2048161 lb/ft2
1 oz/yd2 = 33.90575 g/m2 1 g/m2 = 0.0294935 oz/yd2
1 oz/ft2 = 305.1517 g/m2 1 g/m2 = 0.0032771 oz/ft2
DENSITY
1 lb/ft3 = 16.01846 kg/m3 1 kg/m3 = 0.062428 lb/ft3
1 lb/yd3 = 0.5932764 kg/m3 1 kg/m3 = 1.685555 lb/yd3
1 ton/ yd3 = 1.186553 t/m3 1 t/m3 = 0.8427774 ton/ yd3
FORCE
1 tonf (ton-force) = 8.89644 kN 1 kN = 0.1124045 tonf (ton-force)
1 kip (1,000 lbf) = 4.44822 kN 1 kN = 0.224809 kip (1,000 lb)
1 lbf (pound-force) = 4.44822 N 1 N = 0.224809 lbf (pound-force)
MOMENT OF FORCE
1 lbf· f = 1.355818 N· m 1 N· m = 0.7375621 lbf· f
1 lbf· in = 0.1129848 N· m 1 N· m = 8.8507481 lbf· in
1 tonf· ft = 2.71164 kN· m 1 kN· m = 0.3687805 tonf· ft
1 kip· ft = 1.35582 kN· m 1 kN· m = 0.737561 kip· ft
FORCE PER UNIT LENGTH
1 lb/ft = 14.5939 N/m 1 N/m = 0.0685218 lb/ft
1 lbf/in = 175.1268 N/m 1 N/m = 0.0057101 lb/in
1 tonf/ft = 29.1878 kN/m 1 kN/m = 0.0342609 tonf/ft
PRESSURE, STRESS
1 tonf/in2 = 13.7895 Mpa 1Mpa = 0.0725189 tonf/in2
1 tonf/ft2 = 95.7605 kPa 1 kPa = 0.0104427 tonf/ft2
1 kip/in2 = 6.894757 Mpa 1 Mpa = 0.1450377 kip/in2
1 lbf/in2 = 6.894757 kPa 1 kPa = 0.1450377 lbf/in2
1 lbf/ft2 = 47.8803 Pa 1 Pa = 0.0208854 lbf/ft2
Atmosphere = 101.3250 kPa 1 kPa = 0.0098692 Atmosphere
1 inch mercury = 3.37685 kPa 1 kPa = 0.296134 inch mercury
1 foot water column = 2.98898 kPa 1 kPa = 0.3345623 foot water column
WORK, ENERGY, HEAT
1 kWh (550 ft· lbf/s) = 3.6 MJ 1 MJ = 0.2777778 kWh (550 ft· lbf/s)
1 BTU = 1.055056 kJ 1 kJ = 0.947817 BTU
1 BTU = 1055.056 J 1 J = 0.0009478 BTU
1 ft· lbf = 1.355818 J 1 J = 0.7375621 ft· lbf
HEAT TRANSFER
1 BTU/(ft2· h· °F) = 5.678263 W/(m2· K) 1 W/m2· K = 0.1761102 BTU/(ft2· h· °F)
THERMAL CONDUCTIVITY
1 BTU/(ft· h· °F) = 1.730735 W/(m· K) 1 W/m· K = 0.5777892 BTU/(ft· h· °F)
ILLUMINANCE
1 lm/ft2(footcandle) = 10.76391 lx (lux) 1 lx = 0.092903 lm/ft2(footcandle)
LUMINANCE
1 cd/ft2 = 10.7639 cd/m2 1 cd/m2 = 0.0929031 cd/ft2
1 foot lambert = 3.426259 cd/m2 1 cd/m2 = 0.2918635 foot lambert
1 lambert = 3.183099 kcd/m2 1 kcd/m2 = 0.3141593 lambert