Calculating your gear ratio (to 1) is straightforward once you know the Gear Ratio 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 Gear Ratio Calculator.
What is Gear Ratio?
The Gear Ratio calculation tells you your gear ratio (to 1) from a few simple inputs. The figure you are solving for here is the gear ratio (to 1).
The Gear Ratio formula
The core formula is:
Gear ratio (to 1) = Driven gear teeth ÷ Drive gear teethHere is what each input means:
- Driven gear teeth — a number. Example: 40.
- Drive gear teeth — a number. Example: 10.
How to calculate it step by step
- Write down the driven gear teeth (for example, 40).
- Write down the drive gear teeth (for example, 10).
- Apply the formula above to get your gear ratio (to 1).
- Double-check the result with the Gear Ratio Calculator.
Worked examples
Example 1
| Input / Output | Value |
|---|---|
| Driven gear teeth | 40 |
| Drive gear teeth | 10 |
| Gear ratio (to 1) | 4.000 |
With driven gear teeth of 40 and drive gear teeth of 10, the gear ratio (to 1) works out to 4.000.
Example 2
With driven gear teeth of 80 and drive gear teeth of 10, the gear ratio (to 1) works out to 8.000.
| Result | Value |
|---|---|
| Gear ratio (to 1) | 8.000 |
Example 3
With driven gear teeth of 20 and drive gear teeth of 10, the gear ratio (to 1) works out to 2.000.
| Result | Value |
|---|---|
| Gear ratio (to 1) | 2.000 |
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 Gear Ratio Calculator does it instantly, for free, with the formula and a worked example built in.
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