Conversion factors

Instructions

Multiplying or dividing by a conversion factor is equivalent to multiplying by 1.   Introduction to Chemical Engineering Processes/Units is an excellent source of additional units, conversion factors, and explanations. 

Note that symbols for 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 3 meters is written 3 m, not 3 ms (that would be millisecond).  And 10 grams is 10 g, not 10 gms.
 

Mass

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

(kg m2/J s2)

(Pa m s2/kg)

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

(tonne/1000 kg)

(2.20462 lbm/kg)
(35.27392 oz/kg)
(16 oz/lbm)
(2000 lbm/ton)
(453.593 g/lbm)
(32.1740 lbm/slug)
(14.5939 kg/slug)
(32.174 lbm ft / lbf s2)  (This is often given the symbol gc)

      (2240 lb / long ton)

 

      definitions of symbols

lbm -- pound of mass

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

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 lbf)

ton -- 2000 lbm (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

(1 kg m / N s2) (From definition of N)

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

(32.174 lbm ft/(lbf s2)) (This is often given the symbol gc)

 

      Definitions of symbols

N -- Newton

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

lbm -- pound of mass
poundal -- unit of force in Absolute English System (defined as the force that accelerates 1 lbm 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 lbf)

 

Pressure and stress

(Pa m s2/kg)

((N/m2)/Pa)

(1E6 Pa/MPa)

(100 kPa / bar)

(1.01325E5 (N/m2)/atm)
(101.325 kPa/atm)
(1.01325 bar/atm)

(1.01325E6 (dyne/cm2)/atm)
(760 Torr/atm)
(14.696 (lbf/in2)/atm)
(psi/(lbf/in2))

 

Definitions of symbols

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

lbf -- 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

(J/W s)

(kJ/kW s)

(N m/J)
(kg m2/J s2)

(1000 J/kJ)

(1E7 erg/J)
(dyne cm/erg)
(2.778E-7 kW h/J)
(0.23901 cal/J)
(0.7376 ft lbf/J)
(9.486E-4 Btu/J)

(100,000 Btu/therm)

(105.5 MJ/therm)

(eV/1.602E-19 J)

 

      Definitions of symbols

N -- Newton

J -- Joule

MJ -- megajoule (106 J)

W -- Watt

kW -- kilowatt (1000 w)

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

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

therm -- 100,000 Btu.  Commonly used to price natural gas.

          eV -- Electron volt

 

Power

((J/s)/W)
((0.23901 cal/s)/W)
((0.7376 ft lbf/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 symbols

J -- Joule

W -- watt
V -- volt

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

cal -- calorie

lbf -- 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

TK =TC +273.15

TR =TF +459.67

TR =1.8 TK

TF =1.8 TC +32

TC =( TF -32)/1.8

(1.8 DTC /DTF)
(1.8
DTK /DTR)
(
DTK /DTC)
(
DTR /DTF])

 

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

TR is absolute temperature in degrees Rankine (oR).

TF is temperature in degrees Fahrenheit (oF).

TC is temperature in degrees Celsius (formerly degrees Centigrade; oC)
DTK is the change in temperature in Kelvin (K)

DTR is the change in temperature in degrees Rankine (oR).
DTF is the change in temperature in degrees Fahrenheit (oF).
DTC 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;

 

Definitions of symbols

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

lb_mol -- pound mole (mass in lbm 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 symbols

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 June 13, 2014.  Please send comments and suggestions to W.R. Wilcox