Scale Factor Calculator for Similar Figures
Find scale factor, enlarge or reduce figures, and connect scale to proportional reasoning.
Multiply every dimension by the scale factor to scale a figure
Enter the original and new measurements to find the scale factor.
How to use this calculator
Enter the original measurement and the new measurement. The calculator divides new by original to find the scale factor.
What this means in math class
Scale factor connects proportional reasoning to geometry. When k > 1 the figure enlarges; when 0 < k < 1 it reduces.
Worked examples
Example 1: Enlargement
Original width = 4 cm, new width = 10 cm
- Step 1:Scale factor = new ÷ original
- Step 2:10 ÷ 4 = 2.5
- Step 3:Since 2.5 > 1, this is an enlargement
Example 2: Reduction
Original length = 15 cm, new length = 5 cm
- Step 1:Scale factor = new ÷ original
- Step 2:5 ÷ 15 = 1/3
- Step 3:Since 1/3 < 1, this is a reduction
Frequently asked questions
What is scale factor?
The number you multiply original dimensions by to get new dimensions.
What does a scale factor of 1 mean?
The figures are the same size — no change.
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