SI prefix converter
Convert between metric prefixes. How many milligrams in a kilogram, or microseconds in a minute — the prefix is the same arithmetic whatever the unit.
That's about the same as kilo. That prefix is 10 to the power 3.
What it means
How big is that step?
These are the decimal prefixes. Computer storage sometimes uses binary ones — a kibibyte is 1,024 bytes, not 1,000.
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Three things worth knowing
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Each big step is a thousand
k, M, G, T going up and m, µ, n, p going down: every step multiplies or divides by 1,000. One kilo is a million milli.
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Greek up, Latin down
The large prefixes come from Greek — kilo for thousand, mega for great — and the small ones from Latin: milli from mille, centi from centum. The 1960 revision kept the pattern.
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Capital M, small m
M is mega and m is milli: a factor of a billion decided by the shift key. Kilo is the only large prefix with a lowercase symbol.
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Background
About SI prefixes
Every metric prefix is a power of ten, so converting between them is only ever a matter of moving the decimal point. The main series steps by a thousand: kilo, mega, giga, tera going up, and milli, micro, nano, pico going down.
The odd ones out are hecto, deca, deci and centi, which step by ten, and survive mostly in the centimeter.