Gear Ratio
Calculator
Results
- Gear ratio
- 3.416666
- Output turns per input turn
- 0.292682
- Torque multiplication
- 3.416666
Results
| Gear ratio | 3.416666 |
| Output turns per input turn | 0.292682 |
| Torque multiplication | 3.416666 |
formula-map diagram
- Gear ratio
- 3.416666
- Output turns per input turn
- 0.292682
- Torque multiplication
- 3.416666
Formula breakdown
Formula
ratio = driven teeth ÷ drive teeth= 3.4166666666667
Note
Simplified model: results use idealised textbook relationships and ignore real-world factors such as driving style, load, temperature, aerodynamic and rolling losses, drivetrain efficiency, tyre and brake condition and road surface. CO2 figures are tailpipe only, based on the standard 2.31 kg CO2 per litre of petrol (2.68 kg per litre of diesel), and exclude fuel production and distribution. Use them as estimates, not as legal, safety or load-rating figures.
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See all →Frequently asked questions
What does a gear ratio represent?+
A gear ratio is the ratio of rotational speeds (or equivalently, tooth counts) between two connected gears, describing how many times the input gear must turn to turn the output gear once. It determines the trade-off between rotational speed and torque transmitted through the gear pair.
How is gear ratio calculated from tooth counts?+
Gear ratio = number of teeth on the driven gear ÷ number of teeth on the driving gear. For example, if a 40-tooth gear is driven by a 10-tooth gear, the ratio is 40:10, or 4:1 — the driving gear must turn 4 times to turn the driven gear once.
Why does a higher numerical gear ratio increase torque but reduce speed?+
Because energy is conserved through the gear train, a ratio that makes the output turn slower than the input (a numerically higher ratio) proportionally increases the torque delivered at the output, and vice versa — you trade rotational speed for torque, or torque for speed, but not both simultaneously.
What's a common misconception about combining multiple gear ratios, such as a transmission gear and a final drive ratio?+
People sometimes add gear ratios together instead of multiplying them. To get the overall or 'total' ratio through a drivetrain with multiple reduction stages (like a transmission gear ratio and a differential final drive ratio), you multiply the individual ratios together, not add them.
Does gear ratio alone determine a vehicle's top speed or acceleration?+
No — gear ratio interacts with engine power/torque curves, tire size, and the vehicle's aerodynamics and weight to determine actual performance. A numerically low (tall) final drive ratio can enable a higher top speed but slower acceleration, while a numerically high (short) ratio does the opposite, assuming the same engine and tires.