Metric Prefix Converter
Convert a value from one SI prefix to another — kilo, milli, micro, and the rest.
In the base unit.
A metric prefix scales a unit by a power of ten, so converting between prefixes just shifts that power. For example 5 km = 5000 m, since kilo means 10³ — multiply 5 by 10³ to reach the base unit. The general rule: value × 10 raised to the difference of the two exponents.
What a metric prefix does
Every SI prefix stands for a fixed power of ten attached to a base unit. Kilo (k) is 10³, milli (m) is 10⁻³, micro (µ) is 10⁻⁶, and so on. Because the prefixes are pure powers of ten, changing prefix never changes the quantity — only the digits and the decimal point move. Converting from one prefix to another is a single multiplication by 10 raised to the difference of their exponents.
exp is the prefix exponent: kilo = 3, base = 0, milli = −3, micro = −6
- 1 Find each prefix exponent. For 5 km → m, kilo has exponent 3 and the base unit (m) has exponent 0.
- 2 Subtract: exp_from − exp_to. 3 − 0 = 3, so you multiply by 10³.
- 3 Multiply the value by that power of ten. 5 × 10³ = 5 × 1000 = 5000.
- 4 Attach the new prefix. The answer is 5000 m. A positive difference grows the number; a negative one shrinks it.
SI prefixes
From largest to smallest. The factor is 10 raised to the listed exponent.
| Prefix | Symbol | Factor (10ⁿ) |
|---|---|---|
| tera | T | 10¹² |
| giga | G | 10⁹ |
| mega | M | 10⁶ |
| kilo | k | 10³ |
| hecto | h | 10² |
| deca | da | 10¹ |
| (none) | — | 10⁰ |
| deci | d | 10⁻¹ |
| centi | c | 10⁻² |
| milli | m | 10⁻³ |
| micro | µ | 10⁻⁶ |
| nano | n | 10⁻⁹ |
| pico | p | 10⁻¹² |
Reading the steps along the scale
For the everyday large prefixes — kilo, mega, giga, tera — each step up is a factor of 1000 (10³): 1 GB = 1000 MB = 1 000 000 kB. The same holds going down through milli, micro, nano, pico, where each step divides by 1000. The middle prefixes hecto, deca, deci, and centi break that rhythm with steps of 10, which is why they appear mostly in centimeters and hectares. One symbol to watch: micro is the Greek letter µ (mu), not the letter u — 1 µm is one micrometer, 10⁻⁶ m.