• Share
Send to a Friend via Email

### Your suggestion is on its way!

An email with a link to:

was emailed to:

Thanks for sharing About.com with others!

You can opt-out at any time. Please refer to our privacy policy for contact information.

Discuss in my forum

# Metric Unit Prefixes

## Prefixes of Base Units by Factors of Ten

By Todd Helmenstine

Scientific measurements are made using the metric system.

Siede Preis, Getty Images
Metric or SI (Le Système International d'Unités) units are based on units of ten. Very large or very small numbers are easier to work with when you can replace any scientific notation with a name.

For example: the distance from City A to City B is 8.0 x 103 meters. From the table, 103 can be replaced with the prefix 'kilo'. Now the distance could be stated as 8.0 kilometers or shortened further to 8.0 km.

The distance from Earth to the Sun is approximately 150,000,000,000 meters. You could write this as 150 x 109 m, 150 gigameters or 150 Gm.

The width of human hair runs on the order of 0.000005 meters. Rewrite this as 50 x 10-6m, 50 micrometers, or 50 μm.

 Metric or SI prefixes Prefix symbol x from 10x yotta Y 24 1,000,000,000,000,000,000,000,000 zetta Z 21 1,000,000,000,000,000,000,000 exa E 18 1,000,000,000,000,000,000 peta P 15 1,000,000,000,000,000 tera T 12 1,000,000,000,000 giga G 9 1,000,000,000 mega M 6 1,000,000 kilo k 3 1,000 hecto h 2 100 deca da 1 10 base 0 1 deci d -1 0.1 centi c -2 0.01 milli m -3 0.001 micro μ -6 0.000001 nano n -9 0.000000001 pico p -12 0.000000000001 femto f -15 0.000000000000001 atto a -18 0.000000000000000001 zepto z -21 0.000000000000000000001 yocto y -24 0.000000000000000000000001