Metric prefixes chart

SI prefixes from quecto to quetta.

24 rows
PrefixSymbolPower of tenAs a numberName (short scale)
quetta10³⁰1,000,000,000,000,000,000,000,000,000,000nonillion
ronna10²⁷1,000,000,000,000,000,000,000,000,000octillion
yotta10²⁴1,000,000,000,000,000,000,000,000septillion
zetta10²¹1,000,000,000,000,000,000,000sextillion
exa10¹⁸1,000,000,000,000,000,000quintillion
peta10¹⁵1,000,000,000,000,000quadrillion
tera10¹²1,000,000,000,000trillion
giga10⁹1,000,000,000billion
mega10⁶1,000,000million
kilo10³1,000thousand
hecto10²100hundred
deca10¹10ten
deci10⁻¹0.1tenth
centi10⁻²0.01hundredth
milli10⁻³0.001thousandth
micro10⁻⁶0.000001millionth
nano10⁻⁹0.000000001billionth
pico10⁻¹²0.000000000001trillionth
femto10⁻¹⁵0.000000000000001quadrillionth
atto10⁻¹⁸0.000000000000000001quintillionth
zepto10⁻²¹0.000000000000000000001sextillionth
yocto10⁻²⁴0.000000000000000000000001septillionth
ronto10⁻²⁷0.000000000000000000000000001octillionth
quecto10⁻³⁰0.000000000000000000000000000001nonillionth

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How to use the prefix chart

  1. Find a prefix by name (mega), symbol (M) or number word (million).
  2. Read its power of ten and the number written out.
  3. Multiply a unit by that power: 5 km = 5 × 10³ m = 5,000 m.

Everyday examples

  • kilo (10³): 1 kilometer = 1,000 meters; 1 kilogram = 1,000 grams.
  • mega (10⁶): a 12 megapixel photo has 12 million pixels.
  • giga (10⁹): a 2 GHz processor ticks 2 billion times a second.
  • milli (10⁻³): 1 milliliter is a thousandth of a liter.
  • micro (10⁻⁶): a human hair is roughly 50 to 100 micrometers thick.
  • nano (10⁻⁹): visible light has wavelengths of about 380 to 750 nanometers.

Short and long scale

The names in the last column use the short scale, where a billion is 10⁹, as in English today. Some languages use the long scale, where a billion means 10¹², so prefixes are the safer way to be exact.