SI Prefixes Chart
SI prefixes chart with all 24 prefixes from quecto to quetta, including the 2022 extension: symbol, power of ten and factor for kilo, mega, milli, micro, nano.
For reference. Verify the application conditions and the applicable standard.
Columns
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Visible rows: 24
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| prefix | symbol | power of ten | factor |
|---|---|---|---|
| quetta | Q | 30 | 1E30 |
| ronna | R | 27 | 1E27 |
| yotta | Y | 24 | 1E24 |
| zetta | Z | 21 | 1E21 |
| exa | E | 18 | 1E18 |
| peta | P | 15 | 1E15 |
| tera | T | 12 | 1E12 |
| giga | G | 9 | 1000000000 |
| mega | M | 6 | 1000000 |
| kilo | k | 3 | 1000 |
| hecto | h | 2 | 100 |
| deca | da | 1 | 10 |
| deci | d | -1 | 0.1 |
| centi | c | -2 | 0.01 |
| milli | m | -3 | 0.001 |
| micro | µ | -6 | 0.000001 |
| nano | n | -9 | 1E-9 |
| pico | p | -12 | 1E-12 |
| femto | f | -15 | 1E-15 |
| atto | a | -18 | 1E-18 |
| zepto | z | -21 | 1E-21 |
| yocto | y | -24 | 1E-24 |
| ronto | r | -27 | 1E-27 |
| quecto | q | -30 | 1E-30 |
Quick answers
- The prefix giga has the symbol G and stands for 10 to the power 9. View in table
- The prefix mega has the symbol M and stands for 10 to the power 6. View in table
- The prefix kilo has the symbol k and stands for 10 to the power 3. View in table
- The prefix milli has the symbol m and stands for 10 to the power -3. View in table
- The prefix micro has the symbol µ and stands for 10 to the power -6. View in table
- The prefix nano has the symbol n and stands for 10 to the power -9. View in table
Conditions and notes
SI decimal prefixes including the 2022 extension.
- The prefix column uses international names. Local spelling may differ, while symbols remain unchanged.
Prefixes are decimal factors. Uppercase and lowercase symbols have different meanings. m means milli and M means mega. For example, 1 km = 1000 m. Binary memory prefixes are not included. Ronna, quetta, ronto and quecto were added in 2022 and are included. Join a prefix symbol directly to its unit symbol.
Sources
This table is for preliminary reference. Check the applicable standard and product conditions before use.
- Source 1. Including CGPM 2022 Resolution 3. Accessed: 2026-10-16
- Source 2. 2025 update. Accessed: 2026-10-16
Data version: 2026-10-16