Calculating your scale factor is straightforward once you know the Scale Factor formula and what each input means. This guide explains the method in plain language, walks through a manual calculation, and gives worked examples you can follow — then you can do it instantly with the Scale Factor Calculator.
What is Scale Factor?
The Scale Factor calculation tells you your scale factor from a few simple inputs. The figure you are solving for here is the scale factor.
The Scale Factor formula
The core formula is:
Scale factor = New (scaled) size ÷ Original sizeHere is what each input means:
- New (scaled) size — a number. Example: 15.
- Original size — a number. Example: 10.
How to calculate it step by step
- Write down the new (scaled) size (for example, 15).
- Write down the original size (for example, 10).
- Apply the formula above to get your scale factor.
- Double-check the result with the Scale Factor Calculator.
Worked examples
Example 1
| Input / Output | Value |
|---|---|
| New (scaled) size | 15 |
| Original size | 10 |
| Scale factor | 1.5000 |
| As a percentage | 150.00% |
With new (scaled) size of 15 and original size of 10, the scale factor works out to 1.5000.
Example 2
With new (scaled) size of 30 and original size of 10, the scale factor works out to 3.0000.
| Result | Value |
|---|---|
| Scale factor | 3.0000 |
| As a percentage | 300.00% |
Example 3
With new (scaled) size of 7.5 and original size of 10, the scale factor works out to 0.7500.
| Result | Value |
|---|---|
| Scale factor | 0.7500 |
| As a percentage | 75.00% |
Tips for an accurate result
- Keep your units consistent — mixing, say, months with years or grams with kilograms is the most common source of error.
- Round only at the very end. Rounding inputs early can shift the final answer noticeably.
- Re-run the numbers whenever an input changes, rather than estimating from an old result.
Prefer not to do the maths by hand? — the Scale Factor Calculator does it instantly, for free, with the formula and a worked example built in.
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