About the Metric Prefix Converter
This metric prefix converter moves a number from one SI prefix to another — milli to micro, nano to milli, mega to giga, kilo to the plain base unit and so on. Pick the prefix you have, the prefix you want, and optionally type the unit symbol (m, g, W, Hz, F, B) so the answer reads naturally, such as 5 mm = 5,000 µm.
It is useful for students checking physics and chemistry homework, electronics hobbyists reading capacitor and resistor values (pF, nF, µF), lab workers switching between mg, µg and ng, and anyone handling scientific data where results are quoted with different prefixes. Because every SI prefix is a power of ten, the conversion is exact and works the same for every unit.
All 24 prefixes in the current SI are supported, including ronna, quetta, ronto and quecto added in 2022. Very large and very small answers are also shown in scientific notation, and the table lists your value under every common prefix from tera to pico. Note that computer storage sometimes uses binary prefixes (KiB, MiB) that are powers of 1,024 — those are not SI prefixes.
With the default inputs, the converted value is 5,000. Change any value above to recalculate instantly.
How to use the metric prefix converter
- 1Enter the number you want to convert.
- 2Choose the prefix it is currently in (for example milli).
- 3Choose the prefix you want (for example micro).
- 4Optionally type the unit symbol so the result reads as mm, µF, GHz, etc.
- 5Read the converted value, its scientific notation and the decimal shift.
Formula and method
Every SI prefix stands for a power of ten: kilo = 10^3, milli = 10^−3, micro = 10^−6, nano = 10^−9 and so on. To convert, first express the value in the base unit by multiplying by the source prefix factor, then divide by the target prefix factor. Both steps combine into a single multiplication by 10 raised to the difference of the exponents.
For example milli (−3) to micro (−6) gives a difference of +3, so you multiply by 1,000: 5 mm = 5,000 µm. A negative difference means the number gets smaller — 250 nm is 0.00025 mm. The same rule works for metres, grams, litres, watts, hertz, farads and every other SI unit, because the prefix never changes the unit itself.
- value
- The number you start with, in the source prefix
- from exponent
- Power of ten of the source prefix (e.g. −3 for milli)
- to exponent
- Power of ten of the target prefix (e.g. −6 for micro)
Worked examples
Millimetres to micrometres
Milli is 10^−3 and micro is 10^−6, a difference of 3 powers of ten. 5 × 10^3 = 5,000, so 5 mm equals 5,000 µm.
Nanometres to millimetres
From nano (−9) to milli (−3) the exponent difference is −6, so divide by one million: 250 ÷ 1,000,000 = 0.00025 mm, or 2.5 × 10^−4 mm.
Gigahertz to megahertz
Giga (10^9) to mega (10^6) is a shift of +3, so a 3.2 GHz processor clock is 3.2 × 1,000 = 3,200 MHz.
Microfarads to nanofarads
A common decoupling capacitor is 0.1 µF. Micro (−6) to nano (−9) multiplies by 1,000, giving 100 nF.
Frequently asked questions
How do I convert milli to micro?+
Multiply by 1,000. Milli is 10^−3 and micro is 10^−6, so one milli-unit contains 1,000 micro-units — for example 2 mg = 2,000 µg and 0.5 mm = 500 µm.
How many nano are in a micro?+
There are 1,000 nano-units in one micro-unit, because nano is 10^−9 and micro is 10^−6. So 1 µs = 1,000 ns and 4.7 µF = 4,700 nF.
What are the SI prefixes in order?+
From largest to smallest: quetta (10^30), ronna, yotta, zetta, exa, peta, tera, giga, mega, kilo, hecto, deka, then deci, centi, milli, micro, nano, pico, femto, atto, zepto, yocto, ronto and quecto (10^−30).
Is a kilobyte 1,000 or 1,024 bytes?+
In SI, kilo always means 1,000, so 1 kB = 1,000 bytes. The binary prefix kibi (KiB) means 1,024 bytes. Operating systems sometimes label KiB as KB, which causes the confusion.
What is the symbol for micro?+
The official symbol is the Greek letter mu, µ. When it cannot be typed, "u" is a common substitute (for example uF or ug), and "mc" is used in medicine to avoid confusion with milli.
Which prefixes were added most recently?+
In November 2022 the General Conference on Weights and Measures added ronna (10^27), quetta (10^30), ronto (10^−27) and quecto (10^−30), mainly for data science and physics.