---
tags: [physics, electricity, exponents]
---

# Prefixes for unit of electrical measurement

In electronics we are often dealing with units that are very large or very
small, thus we rely on [exponents](Exponents.md) for formal
expression.

| Prefix | Symbol | Expression as exponent | Expression as decimal value | English word |
| ------ | ------ | ---------------------- | --------------------------- | ------------ |
| Terra- | T      | $10^{12}$              | 1,000,000,000,000           | trillion     |
| Giga-  | G      | $10^9$                 | 1,000,000,000               | billion      |
| Mega-  | M      | $10^6$                 | 1,000,000                   | million      |
| Kilo-  | k      | $10^3$                 | 1,000                       | thousand     |
| Centi- | c      | $10^{-2}$              | 0.01                        | hundredth    |
| Milli- | m      | $10^{-3}$              | 0.001                       | thousandth   |
| Micro- | $\mu$  | $10^{-6}$              | 0.0000001                   | millionth    |
| Nano-  | n      | $10^{-9}$              | 0.0000000001                | billionth    |
| Pico-  | p      | $10^{-12}$             | 0.0000000000001             | trillionth   |

For example, with Amps we tend not to use 1 whole amp as this is far too large
for most electronics. More common is the milliampere (mA) and the microampere
($\mu$A).

A mA is equal to one thousandth of an ampere: 0.001 A. It takes 1000
milliamperes to equal one ampere.

A $\mu$A is equal to one millionth of an ampere: 0.0000001 A. It takes one
million micoramperes to equal one ampere.
