These are the prefixes used in the international SI system of measurement. Notice that the
greyed area includes four non preferred units. Of these the 'centi' prefix (commonly
used for the centimetre) although widely used is in fact a non preferred unit.
The 'deka' prefix is sometimes seen. This is incorrect- it should be 'deca'.
| Prefix | Symbol | Multiplier | Notes |
|---|
| yotta | Y | 1 000 000 000 000 000 000 000 000 | = 10^24 | |
| zetta | Z | 1 000 000 000 000 000 000 000 | = 10^21 | |
| exa | E | 1 000 000 000 000 000 000 | = 10^18 | |
| peta | P | 1 000 000 000 000 000 | = 10^15 | |
| tera | T | 1 000 000 000 000 | = 10^12 | |
| giga | G | 1 000 000 000 | = 10^9 | thousand-million (billion) |
| mega | M | 1 000 000 | = 10^6 | million |
| kilo | k | 1 000 | = 10^3 | thousand |
| hecto | h | 100 | = 100 | hundred |
| deca | da | 10 | = 10 | ten |
| The greyed area are non preferred prefixes |
| deci | d | 0.1 | = 0.1 | tenth |
| centi | c | 0.01 | = 0.01 | hundredth |
| milli | m | 0.001 | = 10^-3 | thousandth |
| micro | µ | 0.000 001 | = 10^-6 | millionth |
| nano | n | 0.000 000 001 | = 10^-9 | thousand-millionth |
| pico | p | 0.000 000 000 001 | = 10^-12 | |
| femto | f | 0.000 000 000 000 001 | = 10^-15 | |
| atto | a | 0.000 000 000 000 000 001 | = 10^-18 | |
| zepto | z | 0.000 000 000 000 000 000 001 | = 10^-21 | |
| yocto | y | 0.000 000 000 000 000 000 000 001 | = 10^-24 | |
person-
