Scale Factors, this GCSE Maths section of Revision Maths explains scale factors and how to calculate them.
The video below provides an overview to calculating scale factors.
A scale factor is a number which is used as a multiplier when scaling.
Scale factors can be used to scale objects in 1, 2 or 3 dimensions. They can be written as either ratios, decimals, fractions or percentages.
Linear Scale Factor
Using linear scale factor a shape can be transformed into another similar shape by changing the size of all its dimensions (either enlargement or reduction) by using a scale factor.
To enlarge or reduce any shape you must begin by working out the scale factor, this is calculated by using the following formula:
For an enlargement = large number ÷ small number
For a reduction = small number ÷ large number
In the example above we are looking for the length of the bigger rectangle 2. This is therefore an enlargement so we use the following formula 12 ÷ 8 = 1.5.
So we therefore know that rectangle 2 is 1.5 times bigger than rectangle 1.