/Planning & Performance
/General Planning

# Conversion Factors, SI Units

The pilot will perform a number of calculations during preflight planning and those we use on the site are listed below for convenient access. Sometimes the use of a special aviation calculator (E6B mechanical models or electronic Jeppesen and other apps) is required, other times it can be done without the use of such devices. Have a look at our E6B Tools above too!

Previous article discussed the formula's used in aviation calculations but sometimes we need to convert between different systems be that volumes, densities or mass. The table below shows some of the common ones used. For common fuel conversions hover your mouse over the image to the right/above. We also provide the most commonly used prefixes that are used with these base units.

## Conversion tables

Using these conversions is quite simple. For example: to convert 150 US gallon to liters is 150 x 3.785 = 567.75 liters. If you want to convert from liters to US gallon then divide the number of liters by the conversion factor.

 Volume, SI unit cubic meter (m3) Convert from: To: Multiply by: m3 ft3 35.315 in3 cm3 16.387 US Gal liters 3.785 UK Gal (Imperial) liters 4.546 US Gal m3 3.785 x 10-3 UK Gal (Imperial) m3 4.546 x 10-3

 Mass (Weight), SI unit kilogram (kg) Convert from: To: Multiply by: kg lb 2.2046 lb g 4.536 x 102

 Pressure, SI unit Newton/square meter (N/m2) Convert from: To: Multiply by: N/m2 (pa) bar 10-5 lbf/in2 (psi) N/m2 (pa) 6.895 x 103 lbf/in2 hPa (mbar) 68.948 kgf/cm2 N/m 9.807 x 104 inHg hPa (mbar) 33.864 Bar Pa (N/m2) 105

 Energy / Power / Heat flow SI unit Watt (W) Convert from: To: Multiply by: hp (electric) kW 0.7457 hp (metric) kW 0.7355 ft.lbf/s W 1.3558 Btu/hr W 0.2931 kWh MJ 3.6 cal J 4.1868 Btu kJ 1.055 Btu kWh 2.9307 x 10-4

## Prefixes

Sometimes I see these prefixes not being used correctly. For example: the use of the kilo prefix is being mistakenly written as uppercase K (which is Kelvin) where it should be k (lowercase). The table below shows them with their factor.

 Commonly used Metric prefixes with SI base units Prefix Symbol Factor Yotta Y 1024 Zeta Z 1021 Exa E 1018 Peta P 1015 Tera T 1012 Giga G 109 Mega M 106 kilo k 103 hecto h 102 deca da 101 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 zepto z 10-21 yocto y 10-24

More commonly used conversions can be found on websites like unitconverters.net, onlineconversion.com and Wikipedia (for what its worth).

Written by EAI.

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