Some Useful Conversions

Conversion formula for temperature

• oF = (oC)(9/5) + 32
• oC = (oF - 32)(5/9)
• oR = oF + 459.67
• K = oC + 273.15

Conversion factors for distance

1 inch (in) = 2.540000 centimeter (cm)
1 foot (ft) = 12 inches (in)
1 yard (yd) = 3 feet (ft)
1 mile (mi) = 5280 feet (ft)

1.3.3 Conversion factors for volume
1 gallon (gal) = 231.0 cubic inches (in3) = 4 quarts (qt) = 8 pints (pt) = 128 fluid ounces (fl. oz.)
= 3.7854 liters (l)
1 milliliter (ml) = 1 cubic centimeter (cm3)

Conversion factors for velocity

1 mile per hour (mi/h) = 88 feet per minute (ft/m) = 1.46667 feet per second (ft/s) = 1.60934
kilometer per hour (km/h) = 0.44704 meter per second (m/s) = 0.868976 knot (knot – international)

Conversion factors for mass

1 pound (lbm) = 0.45359 kilogram (kg) = 0.031081 slugs
1.3.6 Conversion factors for force
1 pound-force (lbf) = 4.44822 newton (N)
1.3.7 Conversion factors for area
1 acre = 43560 square feet (ft2) = 4840 square yards (yd2) = 4046.86 square meters (m2)
1.3.8 Conversion factors for pressure (either all gauge or all absolute)
1 pound per square inch (PSI) = 2.03603 inches of mercury (in. Hg) = 27.6807 inches of water (in.
W.C.) = 6.894757 kilo-pascals (kPa)

Conversion factors for pressure (absolute pressure units only)

1 atmosphere (Atm) = 14.7 pounds per square inch absolute (PSIA) = 760 millimeters of mercury
absolute (mmHgA) = 760 torr (torr) = 1.01325 bar (bar)
1.3.10 Conversion factors for energy or work
1 British thermal unit (Btu – “International Table”) = 251.996 calories (cal – “International Table”)
= 1055.06 joules (J) = 1055.06 watt-seconds (W-s) = 0.293071 watt-hour (W-hr) = 1.05506 x 1010
ergs (erg) = 778.169 foot-pound-force (ft-lbf)

Conversion factors for power

1 horsepower (hp – 550 ft-lbf/s) = 745.7 watts (W) = 2544.43 British thermal units per hour
(Btu/hr) = 0.0760181 boiler horsepower (hp – boiler)

Terrestrial constants

Acceleration of gravity at sea level = 9.806650 meters per second per second (m/s2) = 32.1740 feet
per second per second (ft/s2)
Atmospheric pressure = 14.7 pounds per square inch absolute (PSIA) = 760 millimeters of mercury
absolute (mmHgA) = 760 torr (torr) = 1.01325 bar (bar)
Atmospheric gas concentrations:
• Nitrogen = 78.084 %
• Oxygen = 20.946 %
• Argon = 0.934 %
• Carbon Dioxide (CO2) = 0.033 %
• Neon = 18.18 ppm
• Helium = 5.24 ppm
• Methane (CH4) = 2 ppm
• Krypton = 1.14 ppm
• Hydrogen = 0.5 ppm
• Nitrous Oxide (N2O) = 0.5 ppm
• Xenon = 0.087 ppm
Density of dry air at 20oC and 760 torr = 1.204 mg/cm3 = 1.204 kg/m3 = 0.075 lb/ft3 = 0.00235
slugs/ft3
Absolute viscosity of dry air at 20oC and 760 torr = 0.018 centipoise (cp) = 1.8 × 10−5 Pascalseconds
(Pa·s)