UtilityBaseCalculators
Scale Factor Calculator
Find the scale factor between two sizes, as a decimal, ratio, and percentage.
Updated July 10, 2026
How to use the scale factor calculator
- 1Enter the original size or dimension.
- 2Enter the new, scaled size.
- 3Read the scale factor, ratio, and percentage.
- 4Use the second box to scale any other dimension.
Common uses
- Scaling an architectural or model drawing
- Resizing similar geometric shapes
- Enlarging or reducing an image or plan
- Homework on similarity and scale
Frequently asked questions
How do you find the scale factor?
Divide the new size by the original size. If a shape goes from 4 cm to 12 cm, the scale factor is 12 divided by 4, which is 3 — meaning three times larger. A factor below 1, like 0.5, means the figure was reduced to half size.
What happens to area and volume?
Lengths scale by the factor, but area scales by the factor squared and volume by the factor cubed. So doubling a shape (factor 2) makes its area 4 times larger and its volume 8 times larger. This trips people up constantly.
Is scale factor the same as a ratio?
They express the same relationship. A scale factor of 3 is the ratio 3:1, and a factor of 0.5 is 1:2. The calculator shows both the decimal factor and the simplified ratio so you can use whichever your work needs.
About this tool
The scale factor calculator finds how many times bigger or smaller one figure is than another — the new size divided by the original — and shows it as a decimal, a simplified ratio, and a percentage. A factor above 1 is an enlargement, below 1 a reduction. For similar shapes every corresponding length shares the same factor, while area scales by the factor squared and volume by the factor cubed. A second box applies the factor to any dimension. Everything is calculated in your browser.
Like most tools on UtilityBase, the scale factor calculator runs entirely in your browser — nothing you enter is uploaded or stored on a server. It's free to use with no account required. Browse more calculators here.
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