# Definition:Magnitude

## Definition

The magnitude (or size) of a quantity (either vector or scalar) is a measure of how big it is.

It is usually encountered explicitly in the context of vectors:

If $\mathbf v$ is the vector quantity in question, then its magnitude is denoted:

$\size {\mathbf v}$

or

$v$

## Also defined as

In Euclidean number theory, the term magnitude is used to mean positive real number.