Sign In
A base unit, or fundamental unit, is a unit used for the measurement of a certain quantity. The International System of Units — the SI units — is a set of seven fundamental units agreed on as a system of units in the sciences.
| SI Base Units | ||
|---|---|---|
| Quantity (symbol) | Name | Symbol |
| Mass (m) | kilogram | kg |
| Length (l) | meter | m |
| Time (t) | second | s |
| Temperature (T) | kelvin | K |
| Electric current (I) | ampere | A |
| Luminous intensity (I_v) | candela | cd |
| Amount of substance (n) | mole | mol |
Through multiplications and divisions, the base units can be used to define other units called derived units. One example is velocity (m/s). However, base units cannot themselves be derived from other units.
| Imperial Units | |
|---|---|
| Quantity | Common Units |
| Mass | ounce, pound, ton |
| Length | inch, foot, mile |
| Area | square foot, square yard, square mile |
| Volume | pint, quart, gallon |