Conversion Factors (arranged alphabetically)

Acceleration (L t⁻²)¹

• 1 m/sec² = 3.2808 ft/sec² = 39.3701 in./sec²
• 1 ft/sec² = 0.3048 m/sec² = 12.0 in./sec²
• = 9.80665 m/sec² = 32.174 ft/sec² (standard gravity constant at Earth's surface)

Area (L²)

• 1 ft² = 144.0 in.² = 0.092903 m²
• 1 m² = 1550.0 in.² = 10.7639 ft²
• 1 in.² = 6.4516 × 10⁻⁴ m²

Density (M L³)

• Specific gravity is dimensionless, but has the same numerical value as density expressed in g/cm³; 1 liter = 10⁻³ m³
• 1 kg/m³ = 6.24279 × 10⁻² lbm/ft³ = 3.61273 × 10⁻⁵ lbm/in.³
• 1 lbm/ft³ = 16.0184 kg/m³
• 1 lbm/in.³ = 2.76799 × 10⁴ kg/m³

Energy, also Work or Heat (M L²t⁻²)

• 1.0 Btu = 1055.056 J (joule)
• 1.0 kW‐hr = 3.600 × 10⁶ J
• 1.0 ft‐lbf = 1.355817 J
• 1.0 cal = 4.1868 J
• 1.0 kcal = 4186.8 J

Force (M Lt^‐ 2)

• 1.0 lbf = 4.448221 N
• 1 dyne = 10⁻⁵ N
• 1.0 kg (force) [used in Europe] = 9.80665 N
• 1.0 ton (force) [used in Europe] = 1000 kg (force)
• 1.0 N = 0.2248089 lbf
• 1.0 millinewton (mN) = 10⁻³ N
• Weight is the force acting on a mass being accelerated by gravity ( applies at the Earth's surface)

Length (L)

• 1 m = 3.2808 ft = 39.3701 in.
• 1 ft = 0.3048 m = 12.0 in.
• 1 in. = 2.540 cm = 0.0254 m
• 1 mile = 1.609344 km = 1609.344 m = 5280.0 ft
• 1 nautical mile = 1852.00 m
• 1 mil = 0.0000254 m = 1.00 × 10⁻³ in.
• 1 micron (µm) = 10⁻⁶ m
• 1 astronomical unit (au) = 1.49600 × 10¹¹ m

Mass (M)

• 1 slug = 32.174 lbm
• 1 kg = 2.205 lbm = 1000 g
• 1 lbm = 16 ounces = 0.4536 kg

Power (M L²t⁻³)

• 1 Btu/sec = 0.2924 W (watt)
• 1 J/sec = 1.0 W = 0.001 kW
• 1 cal/sec = 4.186 W
• 1 horsepower = 550 ft‐lbf/sec = 745.6998 W
• 1 ft‐lbf/sec = 1.35581 W

Pressure (M L⁻¹ t⁻²)

• 1 bar = 10⁵ N/m² = 0.10 MPa
• 1 atm = 0.101325 MPa = 14.696 psia
• 1 mm of mercury = 133.322 N/m² (or Pa)
• 1 MPa = 10⁶ N/m²
• 1 psi or lbf/in.² = 6894.757 N/m²

Speed (or linear velocity) (L t⁻¹)

• 1 ft/sec = 0.3048 m/sec = 12.00 in./sec
• 1 m/sec = 3.2808 ft/sec = 39.3701 in./sec
• 1 knot = 0.5144 m/sec
• 1 mile/hr = 0.4770 m/sec

Specific Heat (L² t⁻² T⁻¹)

• 1 g‐cal/g‐°C = 1 kg‐cal/kg‐K = 1 Btu/lbm‐°F = 4.186 J/g‐°C = 1.163 × 10⁻³ kW‐hr/kg‐K

Temperature (T)

• 1 K = (9/5)°R = 1.80°R
• 0°C = 273.15 K
• 0°F = 459.67°R
• °C = (5/9)(°F − 32) and °F = (9/5)°C + 32

Time (t)

• 1 mean solar day = 24 hr = 1440 min = 86, 400 sec
• 1 calendar year = 365 days = 3.1536 × 10⁷ sec

Viscosity (M L⁻¹ t⁻¹)

• 1 centistoke = 1.00 × 10⁻⁶ m²/sec (kinematic viscosity)
• 1 centipoise = 1.00 × 10⁻³ kg/m sec
• 1 lbf‐sec/ft² = 47.88025 kg/m sec

Constants

	Mechanical equivalent of heat = 4.186 joule/cal = 777.9 ft‐lbf/Btu = 1055 joule/Btu
	Universal gas constant = 8314.3 J/kg‐mol‐K = 1545 ft‐lbf/lbm‐mol‐°R
	Molecular volume of an ideal gas = 22.41 liter/kg‐mol at standard conditions
	Electron charge = 1.60218 × 10−19 coulomb
	Permittivity of vacuum = 8.854187 × 10−12 farad/m
	Gravitational constant = 6.674 × 10−11 m3/kg‐sec2
	Boltzmann's constant	1.38065003 × 10−23 J/K
	Electron mass	9.109381 × 10−31 kg
	Avogadro's number	6.02252 × 1026/kg‐mol
	Stefan–Boltzmann constant	5.6696 × 10−8 W/m2‐K−4