SI CONVERSIONS

SI Units & Conversions

Basic Units of Measure


Length	Meter (m)
Mass	Kilograms (kg)
Time	second (s)
Electric Current	Ampere (A)
Therm Temperature	Kelvin (K)
Measured Temperature	Celsius (°C)
Force	Newton (N) (kgm/s²)
Pressure	Pascal (Pa) (N/m²)
Energy	Joule (J) (Nm)

Conversion Factors

Acceleration


1ft/sec²	= 0.3048 m/s²
32.2 Ft/sec²	= 9.80665 m/s²

Airflow per Area


1 cfm/ft²	= 0.00508 m³/sm²

Area


1 in²	= 645.15 mm²
	= 6.4516 x 10-4 m²
1 Ft²	= 92903.04 mm²
	= 0.09290304 m²
1 yd²	= 0.836127 m²
1 mile²	= 2.58999 km²
1 acre	= 4046.86 m²
1 hectare	= 10 000 m²

Coefficient of Heat Transfer


1 BTU/hr ft² °F	= 5.67826 W/m²K

Conductivity (Thermal)


1 BTU in Ft² °F	= 0.144228 W/m K
1 BTU/hr Ft °F	= 1.73073 W/m K

Density


1 lb/in³	= 2.768 x 104 kg/m³
1 BTU/hr Ft °F	= 27.68 kg/L
1 lb/ft³	= 16.0185 kg/m³
Density of Dry air	= 1.2 kg/m³ @ 21°C
Density of Moist Air	= 1.184 kg/m³ @ 21°C 50% RH

Energy


1 kWhr	= 3.6 MJ
1 BTU	= 1.05506 kJ
1 Therm	= 105.506 MJ

Heat Flow


1 BTU/hr	= 0.293071 W

Length


1 Inch	= 25.4 mm
	= 0.0254 m
1 Foot	= 304.8 mm
	= 0.3048 m
1 Yard	= 0.9144 m
1 mile	= 1.609344 km

Mass


1 oz	= 28.3495 g
	= 0.02835 kg
1 lb	= 0.45359 kg
1 ton	= 1016.05 kg

Mass Flow Rate


1 lb/hr	= 0.00012599 kg/s
1 lb/m	= 0.00756 kg/s
1 lb/s	= 0.453592 kg/s

Power


1 HP	= 0.7457 kW

Pressure


1 psi	= 6.89476 kPa
1 in HG	= 3.38639 kPa
1 ins Water	= 0.24908 kPa
14.696 psi	= 101.325 kPa

Specific Heat Capacity


For Dry Air	= 1.005 kJ/kgK
For Water Vapour	= 1.89 KJ/KgK
For Moist Air	= 1.025 KJ/KgK
For Water	= 4.1868 KJ/KgK

Specific Volume


For Dry Air	= 0.833 m³/kg @ 21°C
Moiste Air	= 0.845 m³/kg @ 21°C
Water	= 1 l/kg

Temperature


°C	= K – 273.15
°F	= 1.8°C+32
°C	= (°F – 32)/1.8

Torque


1 lbf ft	= 1.35582 Nm
Torque	= ( kW(output) * 9560 ) / rpm

Universal Gas Constant


Gas Constant, air	= 287 J/kg K
Gas Constant, Water Vapour	= 462 J/kg K

Velocity


1 fps	= 0.3048 m/s
1 fpm	= 0.00508 m/s
1 mph	= 1.609344 km/h

Volume


1 cu In	= 16387 mm³
	= 1.6387 x 10-5 m³
	= 16.3871 ml
1 cu Ft	= 28.3 x 106 mm³
	= 0.0283168 m³
	= 28.3168 L

Volumetric Flow


1 CFM	= 0.000471947 m³/s
	= 0.471947 l/s
1 ft³/s	= 0.0283168 m³/s

Decimal Multipliers


Tera	T = 1012
Giga	G = 109
Mega	M = 106
Kilo	k = 103
Hecto	h = 102
Deca	da = 10
Deci	d = 10-1
Centi	c = 10-2
Milli	m = 10-3
Micro	µ = 10-6
Nano	n = 10-9
Pico	p = 10-12
Femto	f = 10-15
Atto	a = 10-18

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