Conversion factors

Instructions

Multiplying or dividing by a conversion factor is equivalent to multiplying by 1. For additional conversion factors and units, see Section 1 in Perry's Chemical Engineers' Handbook or Section 1 of the Handbook of Chemistry and Physics. Units are always singular. That is, for example, an elapsed time of 5 minutes is written as 5 min, not 5 mins. A distance of 5 meters is written 5 m, not 5 ms (that would be millisecond).

Mass

(2.20462 lb_m/kg)
(1000 g/kg)
(1000 kg/metric ton)

(tonne/1000 kg)
(35.27392 oz/kg)
(16 oz/lb_m)
(2000 lb_m/ton)
(453.593 g/lb_m)
(32.1740 lb_m/slug)
(14.5939 kg/slug)
(32.174 lb_m ft / lb_f s²) (This is often given the symbol g_c)

(1 kg m / N s²) (Basically the definition of N, i.e. the force required to accelerate 1 kg by 1m/s².)

(2240 lb / long ton)

definitions of symbols

lb_m -- pound of mass

lb_f -- pound of force (used in English Engineering System; force required to accelerate 1 lb_m by 32.174 ft/s²; approximately the weight of 1 lb_m)

kg -- kilogram (1000 g)

metric ton -- 1000 kg (also called tonne)

oz -- ounce
slug -- mass unit in English Gravitational System (defined as the mass accelerated to 1 ft/s² by a force of 1 lb_f)

ton -- 2000 lb_m (also called “short ton”)

long ton -- 2240 lb (also called “gross ton,” “weight ton” and “imperial ton”)

g -- gram

N -- Newton

Length

(100 cm/m)
(1000 mm/m)
(1E6 micron/m)
(1E10 Å /m)
(2.54 cm/in)
(39.37 in/m)
(3.2808 ft/m)
(1.0936 yd/m)
(0.0006214 mile/m)
(30.48 cm/ft)
(0.3048 m/ft)
(3 ft/yd)
(12 in/ft)
(5280 ft/mile)

definitions of symbols

cm -- centimeter (0.01 m)

in -- inch

mm -- millimeter (0.001 m)

micron -- micrometer (10^-6 m) (also often written mm)

Å -- Angstrom unit (10^-10m)

m -- meter

ft -- foot

yd -- yard

Volume

(1000 liter/m³)
(1E6 cm³/m³)
(1E6 ml/m³)
(35.3145 ft³/m³)
(220.83 imperial_gal/m³)
(264.17 gal/m³)
(1056.68 qt/m³)
(1728 in³/ft³)
(7.4805 gal/ft³)
(0.028317 m³/ft³)
(28.317 L/ft³)

(1000 L/m³)
(28317 cm³/ft³)

Definitions of symbols

ml -- milliliter

gal -- U.S. gallon

L -- liter

qt -- quart

Time

(60 s/min)
(60 min/h)
(24 h/day)
(365.25 day/year)
(3600 s/h)

Force

(1E5 dyne/N)
(1E5 g cm/(N s²))
(0.22481 lb_f /N)
(4.4482 N/lb_f)
(4.4482E5 dyne/lb_f)
(0.0310810 lb_f/poundal)
(0.1382250 N/poundal)
(lb_m ft/(poundal s²))
(slug ft/(lb_f s²))

(32.174 lb_m ft/(lb_f s²)) (This is often given the symbol g_c)

(1 kg m / N s²)

Definitions of units

N -- Newton

lb_f -- pound of force in English Engineering System (force required to accelerate 1 lb_m by 32.174 ft/s²; approximately the weight of 1 lb_m)

lb_m -- pound of mass
poundal -- unit of force in Absolute English System (defined as the force that accelerates 1 lb_m by 1 ft/s²)
slug -- unit of mass in English Gravitational System (defined as the mass accelerated to 1 ft/s² by a force of 1 lb_f)

Pressure and stress

(1.01325E5 (N/m²)/atm)
((N/m²)/Pa)
(1E6 Pa/MPa)
(101.325 kPa/atm)
(1.01325 bar/atm)

(100 kPa / bar)
(1.01325E6 (dyne/cm²)/atm)
(760 Torr/atm)
(14.696 (lb_f/in²)/atm)
(psi/(lb_f/in²))

Definitions of units

guage pressure = absolute pressure - 1 atm (e.g., psig and barg)

N -- Newton

Pa -- Pascal (N/m²)

MPa -- megaPascal (10⁶Pa)

kPa -- kiloPascal (10³Pa)

atm -- atmosphere

bar -- bar

lb_f -- pound force

Torr -- named after Torricelli and defined as 1/760 atm, replacing mmHg.

psi -- pound force per square inch

psia -- pound force per square inch absolute

psig -- pound force per square inch guage (psig = psia - 14.696)

Energy

(N m/J)
(1E7 erg/J)
(dyne cm/erg)
(2.778E-7 kW h/J)
(0.23901 cal/J)
(1000 J/kJ)
(0.7376 ft lb_f/J)
(9.486E-4 Btu/J)

(100,000 Btu/therm)

(105.5 MJ/therm)

(J/W s)

(kJ/kW s)

(eV/1.602E-19 J)

Definitions of units

N -- Newton

J -- Joule

MJ -- megajoule (10⁶ J)

W -- Watt

kW -- kilowatt (1000 w)

cal -- calorie (heat to raise 1 g of water by 1^oC)

Btu -- British thermal unit (heat to raise 1 lb_m of water by 1^oF).

therm -- 100,000 Btu. Commonly used to price natural gas (see units for measuring natural gas).

eV -- Electron volt

Power

((J/s)/W)
((0.23901 cal/s)/W)
((0.7376 ft lb_f/s)/W)
((9.486E-4 Btu/s)/W)
(1.341E-3 hp/W)
(1000 W/kW)
(W/V A)
(W/A² W)

(ton refrig/3.517 kW)

Definitions of units

J -- Joule

W -- watt
V -- volt

A -- ampere (1 coulomb/s)
W-- ohm (resistance)

cal -- calorie

lb_f -- pound force

Btu -- British thermal unit

hp -- horsepower

ton refrig -- ton of refrigeration -- that required to form 1 ton of ice per day (12,000 Btu/h)

Viscosity

((0.01g/cm s)/cp)

(1000 cp/Pa.s)

cp -- centipoise

Temperature

T_K =T_C +273.15

T_R =T_F +459.67

T_R =1.8 T_K

T_F =1.8 T_C +32

T_C =( T_F -32)/1.8

(1.8 DT_C /DT_F)
(1.8 DT_K /DT_R)
(DT_K /DT_C)
(DT_R /DT_F])

T_K is absolute temperature in kelvin (K; no longer degrees Kelvin or ^oK)

T_R is absolute temperature in degrees Rankine (^oR).

T_F is temperature in degrees Fahrenheit (^oF).

T_C is temperature in degrees Celsius (formerly degrees Centigrade; ^oC)
DT_K is the change in temperature in Kelvin (K)

DT_R is the change in temperature in degrees Rankine (^oR).
DT_F is the change in temperature in degrees Fahrenheit (^oF).
DT_C is the change in temperature in degrees Celsius (^oC).

Ideal gas constant

R =8.314 m³ Pa/mol/K;

R =0.08314 liter bar/mol/K;

R =0.08206 liter atm/mol/K;

R =62.36 liter torr/mol/K;

R =0.7302 ft³ atm/lb mol ^oR;

R =10.73 ft³ psia/lb mol ^oR;

R =8.314 J/mol K;

R =1.987 cal/mol K;

R =1.987 Btu/lb mol ^oR;

mol -- gram mole (mass in g divided by molecular weight)

lb_mol -- pound mole (mass in lb_m divided by molecular weight)

psia -- pound force per square inch absolute

atm -- atmosphere

K -- Kelvin

^oR -- degrees Rankine

cal -- calorie

Btu -- British thermal unit

Electrical

(W/V A)
(W/A² W)
(1000 W/kW)
(V/A W)
(s/F W)
(C/A s)
(Hz s)
(S V/A)

Definitions of units

J -- Joule

W -- watt
V -- volt

A -- ampere (1 coulomb/s)
C -- coulomb (unit of charge)
W -- ohm (resistance)

S -- siemens (conductance = 1/resistance)

F -- Farad (capacitance)

Hz - Hertz (frequency)

Last revised May 14, 2010. Please send comments and suggestions to W.R. Wilcox