Primary Standards & Exact/Derived Conversions

PRIMARY STANDARDS*

Meter

Length equal to 1,650,763.73 wavelengths in vacuum of the radiation corresponding to the transition between the levels 2 p₁₀ and 5 d₅ of the krypton-86 atom.

Kilogram

Mass equal to the mass of the international prototype of the kilogram. This is a particular cylinder of platinum-iridium alloy that is preserved in a vault at Sevres, France by the International Bureau of Weights and Measures.

Second

Time duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium-133 atom.

DERIVED STANDARD

Newton

The force that gives to a mass of 1 kilogram an acceleration of 1 meter per sec. per sec.

EXACT CONVERSIONS*

1 pascal = 1 newton/meter²

1 atmosphere = 101,325 pascals

1 bar = 100,000 pascals

1 centipoise = 0.001 newton-second/meter²

1 centistoke = 1 x 10^-6 meter²/second

1 fluid ounce (U.S.) = 2.95735295625 x 10^-5 meter³

1 foot = 0.3048 meter

1 gallon (U.S.) = 3.785411784 x 10^-3 meter³

1 gram = 0.001 kilogram

1 inch = 0.0254 meter

1 kilogram force = 9.80665 newtons

1 liter = 0.001 meter³

1 micron = 1 x 10^-6 meter

1 milliliter = 1 x 10^-6 meter³

1 ounce mass (avdp) = 0.028349523125 kilogram

1 pound force (avdp) = 4.4482216152605 newtons

1 pound mass (avdp) = 0.45359237 kilogram

DERIVED CONVERSIONS:

1 foot of H₂O at 4°C = 2988.98 pascals

1 gram/centimeter³ = 1000 kilograms/meter³

1 inch of H₂O at 4°C = 249.082 pascals

1 inch of Hg at 0°C = 3386.389 pascals

1 pound_F/inch²= 6894.7572 pascals

1 pound_M/inch³= 27,679.905 kilograms/meter³

1 quart (U.S.) = 9.4635295 x 10^-4 meter³

1 drop = 50 microliters

1 bar = 14.503774 pound_F/inch²

*Exact by National Bureau of Standards definition