公制標準參考
完整 24 個國際單位制 (SI) 字首速查矩陣
國際單位制（SI）定義了從 10⁻³⁰ 到 10³⁰ 跨越 60 個數量級的 24 個字首。
| 字首 | 符號 | 10 的次方 | 數量級名稱 | 乘數值 |
|---|---|---|---|---|
| quetta | Q | 10³⁰ | Septillion | 1,000,000,000,000,000,000,000,000,000,000 |
| ronna | R | 10²⁷ | Sextillion | 1,000,000,000,000,000,000,000,000,000 |
| yotta | Y | 10²⁴ | Septillion (short) | 1,000,000,000,000,000,000,000,000 |
| zetta | Z | 10²¹ | Sextillion | 1,000,000,000,000,000,000,000 |
| exa | E | 10¹⁸ | Quintillion | 1,000,000,000,000,000,000 |
| peta | P | 10¹⁵ | Quadrillion | 1,000,000,000,000,000 |
| tera | T | 10¹² | Trillion | 1,000,000,000,000 |
| giga | G | 10⁹ | Billion | 1,000,000,000 |
| mega | M | 10⁶ | Million | 1,000,000 |
| kilo | k | 10³ | Thousand | 1,000 |
| hecto | h | 10² | Hundred | 100 |
| deca | da | 10¹ | Ten | 10 |
| base unit | — | 10⁰ | One (Unity) | 1 |
| deci | d | 10⁻¹ | Tenth | 0.1 |
| centi | c | 10⁻² | Hundredth | 0.01 |
| milli | m | 10⁻³ | Thousandth | 0.001 |
| micro | µ | 10⁻⁶ | Millionth | 0.000 001 |
| nano | n | 10⁻⁹ | Billionth | 0.000 000 001 |
| pico | p | 10⁻¹² | Trillionth | 0.000 000 000 001 |
| femto | f | 10⁻¹⁵ | Quadrillionth | 0.000 000 000 000 001 |
| atto | a | 10⁻¹⁸ | Quintillionth | 0.000 000 000 000 000 001 |
| zepto | z | 10⁻²¹ | Sextillionth | 0.000 000 000 000 000 000 001 |
| yocto | y | 10⁻²⁴ | Septillionth | 0.000 000 000 000 000 000 000 001 |
| ronto | r | 10⁻²⁷ | Octillionth | 10⁻²⁷ |
| quecto | q | 10⁻³⁰ | Nonillionth | 10⁻³⁰ |