SI Prefixes Reference
Complete table of SI metric prefixes from quetta (10³⁰) to quecto (10 ⁻³⁰) with adoption years.
| Prefix | Symbol | Factor | Adopted |
|---|---|---|---|
| quetta | Q | 10³⁰ | 2022 |
| ronna | R | 10²⁷ | 2022 |
| yotta | Y | 10²⁴ | 1991 |
| zetta | Z | 10²¹ | 1991 |
| exa | E | 10¹⁸ | 1975 |
| peta | P | 10¹⁵ | 1975 |
| tera | T | 10¹² | 1960 |
| giga | G | 10⁹ | 1960 |
| mega | M | 10⁶ | 1873 |
| kilo | k | 10³ | 1795 |
| hecto | h | 10² | 1795 |
| deca | da | 10¹ | 1795 |
| (base) | — | 10⁰ | — |
| deci | d | 10⁻¹ | 1795 |
| centi | c | 10⁻² | 1795 |
| milli | m | 10⁻³ | 1795 |
| micro | μ | 10⁻⁶ | 1873 |
| nano | n | 10⁻⁹ | 1960 |
| pico | p | 10⁻¹² | 1960 |
| femto | f | 10⁻¹⁵ | 1964 |
| atto | a | 10⁻¹⁸ | 1964 |
| zepto | z | 10⁻²¹ | 1991 |
| yocto | y | 10⁻²⁴ | 1991 |
| ronto | r | 10⁻²⁷ | 2022 |
| quecto | q | 10⁻³⁰ | 2022 |
Cite this page
UnitConvertLab. (2026). SI Prefixes Reference. UnitConvertLab. Retrieved from https://unitconvertlab.com/reference/si-prefixes