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Prefixes Converter

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Metric prefixes, or SI prefixes, are the words and letters put in front of a unit to multiply it by a power of ten: the kilo in kilometer means a thousand meters, and the milli in millimeter a thousandth. This converter moves a number between prefixes, from zepto (10⁻²¹) to zetta (10²¹), whatever the unit.

How to convert between prefixes

Type a value into the field of its prefix, and every other prefix is calculated at once. By hand, count the powers of ten between the two prefixes:

  1. 4.7 kilo to mega: kilo is 10³ and mega 10⁶, three powers apart, so divide by 1,000.

    4.7 k = 0.0047 M

  2. 0.25 milli to micro: milli is 10⁻³ and micro 10⁻⁶, so multiply by 1,000.

    0.25 m = 250 µ

  3. 3 giga to the plain unit: multiply by 10⁹.

    3 G = 3,000,000,000

So 4.7 kΩ is 0.0047 MΩ, 0.25 ms is 250 µs, and 3 GHz is 3,000,000,000 Hz.

Prefixes in use

Prefix Symbol Factor Example
tera T 10¹² a 2 TB hard drive
giga G 10⁹ a 3 GHz processor
mega M 10⁶ a 12 MP camera
kilo k 10³ a 5 km run
centi c 10⁻² a 30 cm ruler
milli m 10⁻³ a 500 mg tablet
micro µ 10⁻⁶ a 10 µF capacitor
nano n 10⁻⁹ a 5 nm chip process
pico p 10⁻¹² a 22 pF capacitor

Since 2022 there are also ronna and quetta (10²⁷ and 10³⁰) and ronto and quecto (10⁻²⁷ and 10⁻³⁰), after yotta and yocto (10²⁴ and 10⁻²⁴).

List of prefixes

The prefixes and their conversion factors:

  • Zetta (Z): 1 Z = 10^21 (1,000,000,000,000,000,000,000) times the base unit.

  • Exa (E): 1 E = 10^18 (1,000,000,000,000,000,000) times the base unit.

  • Peta (P): 1 P = 10^15 (1,000,000,000,000,000) times the base unit.

  • Tera (T): 1 T = 10^12 (1,000,000,000,000) times the base unit.

  • Giga (G): 1 G = 10^9 (1,000,000,000) times the base unit.

  • Mega (M): 1 M = 10^6 (1,000,000) times the base unit.

  • Kilo (k): 1 k = 10^3 (1,000) times the base unit.

  • Hecto (h): 1 h = 10^2 (100) times the base unit.

  • Deka (da): 1 da = 10^1 (10) times the base unit.

  • None: The base unit itself, without any prefix.

  • Deci (d): 1 d = 10^(-1) (0.1) times the base unit.

  • Centi (c): 1 c = 10^(-2) (0.01) times the base unit.

  • Milli (m): 1 m = 10^(-3) (0.001) times the base unit.

  • Micro (µ): 1 µ = 10^(-6) (0.000001) times the base unit.

  • Nano (n): 1 n = 10^(-9) (0.000000001) times the base unit.

  • Pico (p): 1 p = 10^(-12) (0.000000000001) times the base unit.

  • Femto (f): 1 f = 10^(-15) (0.000000000000001) times the base unit.

  • Atto (a): 1 a = 10^(-18) (0.000000000000000001) times the base unit.

  • Zepto (z): 1 z = 10^(-21) (0.000000000000000000001) times the base unit.

Frequently asked questions

Do prefixes work the same for computer storage?

In the SI, yes: a kilobyte is 1,000 bytes. But computers often count in binary, with kibi, mebi and gibi steps of 1,024. See the Data Storage Converter.

Is a capital M different from a small m?

Yes, and it matters: M is mega, a million, and m is milli, a thousandth. 1 MW is a billion times 1 mW.