How this conversion works
SI prefixes are powers of ten that can be attached to any SI unit: kilo means 10³, milli 10⁻³, and so on. Converting between prefixes multiplies by the ratio of their powers of ten.
Ronna, quetta, ronto and quecto were added in 2022 by the General Conference on Weights and Measures.
Formula: result = value × 10^(source exponent − target exponent)
Where this conversion is used
- Moving between kilo-, mega- and giga- values in engineering and electronics.
- Converting milli-, micro- and nano- quantities in science and medicine.
- Checking scientific notation when reading datasheets.
Worked example: 5 megawatts in kilowatts
- Mega = 10⁶, kilo = 10³.
- 5 × 10^(6 − 3) = 5,000 kW.
Unit definitions
| Unit | In units | Note |
|---|---|---|
| Quetta (Q) | 1e30 | 10^30 |
| Ronna (R) | 1e27 | 10^27 |
| Yotta (Y) | 1e24 | 10^24 |
| Zetta (Z) | 1e21 | 10^21 |
| Exa (E) | 1e18 | 10^18 |
| Peta (P) | 1e15 | 10^15 |
| Tera (T) | 1,000,000,000,000 | 10^12 |
| Giga (G) | 1,000,000,000 | 10^9 |
| Mega (M) | 1,000,000 | 10^6 |
| Kilo (k) | 1,000 | 10^3 |
| Hecto (h) | 100 | 10^2 |
| Deca (da) | 10 | 10^1 |
| No prefix (unit) (—) | 1 | |
| Deci (d) | 0.1 | 10^-1 |
| Centi (c) | 0.01 | 10^-2 |
| Milli (m) | 0.001 | 10^-3 |
| Micro (µ) | 0.000001 | 10^-6 |
| Nano (n) | 1e-9 | 10^-9 |
| Pico (p) | 1e-12 | 10^-12 |
| Femto (f) | 1e-15 | 10^-15 |
| Atto (a) | 1e-18 | 10^-18 |
| Zepto (z) | 1e-21 | 10^-21 |
| Yocto (y) | 1e-24 | 10^-24 |
| Ronto (r) | 1e-27 | 10^-27 |
| Quecto (q) | 1e-30 | 10^-30 |
Mega to kilo
| Mega (M) | Kilo (k) |
|---|---|
| 0.5 | 500 |
| 1 | 1,000 |
| 2.5 | 2,500 |
| 5 | 5,000 |
| 10 | 10,000 |
Milli to micro
| Milli (m) | Micro (µ) |
|---|---|
| 0.001 | 1 |
| 0.01 | 10 |
| 0.5 | 500 |
| 1 | 1,000 |
| 10 | 10,000 |
Things to watch for
- Binary prefixes for data (kibi, mebi, gibi) are powers of 1,024 and are covered by the Data Storage Converter.
- Prefixes apply to the unit only once: write 5 µm, never 5 mmm.
Precision and sources
Results are calculated from the definitions above and rounded to 12 significant digits; the converter shows up to eight decimal places and the tables four. Reference: BIPM, The International System of Units (SI Brochure), 9th edition (2019).
Frequently asked questions
Can I use this for any unit?
Yes, as long as both values use the same unit — for example kilometers to millimeters or megawatts to kilowatts. For squared or cubed units (km², cm³) the exponent also applies to the prefix, so use the Area or Volume Converter instead.
Is kilo written k or K?
Lowercase k. Uppercase K is the kelvin.