Magnitude of the vector is equal to its length, which can be found using the formula:

From the formula above follows that the length of the vector is the scalar always greater than or equal to zero.

Formula for vector magnitude calculation can be derived from the simple geometrical considerations:

Vectors coordinates are equal to its x and y components, therefore
the length of the vector is the value of the hypotenuse of right-angled triangle, which can be found by using the Pythagorean theorem.