SI Prefix Chart
This chart lists the symbol, power of ten and decimal factor of all 24 SI prefixes adopted by the CGPM, from quetta at 10³⁰ to quecto at 10⁻³⁰ in descending order.
24 rows
| quetta | Q | 10^30 | 1e+30 |
| ronna | R | 10^27 | 1e+27 |
| yotta | Y | 10^24 | 1e+24 |
| zetta | Z | 10^21 | 1e+21 |
| exa | E | 10^18 | 1e+18 |
| peta | P | 10^15 | 1e+15 |
| tera | T | 10^12 | 1e+12 |
| giga | G | 10^9 | 1e+9 |
| mega | M | 10^6 | 1e+6 |
| kilo | k | 10^3 | 1,000 |
| hecto | h | 10^2 | 100 |
| deca | da | 10^1 | 10 |
| deci | d | 10^-1 | 0.1 |
| centi | c | 10^-2 | 0.01 |
| milli | m | 10^-3 | 0.001 |
| micro | µ | 10^-6 | 1e-6 |
| nano | n | 10^-9 | 1e-9 |
| pico | p | 10^-12 | 1e-12 |
| femto | f | 10^-15 | 1e-15 |
| atto | a | 10^-18 | 1e-18 |
| zepto | z | 10^-21 | 1e-21 |
| yocto | y | 10^-24 | 1e-24 |
| ronto | r | 10^-27 | 1e-27 |
| quecto | q | 10^-30 | 1e-30 |
Source: SI prefixes as adopted by the CGPM; ronna, quetta, ronto and quecto were added at the 27th CGPM in 2022.
Notes
Prefixes are exact by definition. They may not be compounded: a millionth of a metre is a micrometre, never a millimillimetre.
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