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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:

$\size {\mathbf v}$



Also defined as

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

Also known as

The magnitude of a vector is also referred to as its module or modulus in some older books.

Some sources refer to it as the absolute value of the vector.

Also see


in which context it is applied to a force only