The SI prefixes are the 20 power-of-10 prefixes specified by the Bureau International des Poids et Mesures (BIPM) for use in the International System of Units (SI). They are summarized in the table below, using the American spelling 'deka' instead of 'deca,' and specified by NIST Special Publication SP811 (Thompson and Taylor 2008, p. iv).
| prefix | symbol |  |  | decimal | (American) English word |
| yotta | Y |  |  | 1 000 000 000 000 000 000 000 000 | septillion |
| zetta | Z |  |  | 1 000 000 000 000 000 000 000 | sextillion |
| exa | E |  |  | 1 000 000 000 000 000 000 | quintillion |
| peta | P |  |  | 1 000 000 000 000 000 | quadrillion |
| tera | T |  |  | 1 000 000 000 000 | trillion |
| giga | G |  |  | 1 000 000 000 | billion |
| mega | M |  |  | 1 000 000 | million |
| kilo | k |  |  | 1 000 | thousand |
| hecto | h |  |  | 100 | hundred |
| deka | da |  |  | 10 | ten |
 |  | 1 | one | ||
| deci | d |  |  | 0.1 | tenth |
| centi | c |  |  | 0.01 | hundredth |
| milli | m |  |  | 0.001 | thousandth |
| micro |  |  |  | 0.000 001 | millionth |
| nano | n |  |  | 0.000 000 001 | billionth |
| pico | p |  |  | 0.000 000 000 001 | trillionth |
| femto | f |  |  | 0.000 000 000 000 001 | quadrillionth |
| atto | a |  |  | 0.000 000 000 000 000 001 | quintillionth |
| zepto | z |  |  | 0.000 000 000 000 000 000 001 | sextillionth |
| yocto | y |  |  | 0.000 000 000 000 000 000 000 001 | septillionth |
