Gear
Gear Ratio Calculator
Gear ratio from tooth counts or diameters, with output speed, torque and direction.
ratio = driven teeth ÷ driving teeth
Also called gearing calculator · gear teeth ratio
Engineering · 5 calculators
Gear Calculators
Gear ratio, output speed and torque, pitch diameter, module and diametral pitch, compound gear trains and final drive.
Gear
Gear Diameter Calculator
Pitch, outside and root diameter of a spur gear from its module and tooth count.
pitch diameter = module × teeth
Also called pitch diameter · gear size calculator
Gear
Gear Module Calculator
Gear module from pitch diameter and teeth, with the centre distance for a meshing pair.
module = pitch diameter ÷ number of teeth…
Also called module from diameter · metric gear module
Gear
Compound Gear Ratio Calculator
Overall ratio of a multi-stage gear train, with output speed and torque at each stage.
total ratio = ratio₁ × ratio₂ × ratio₃ …
Also called gear train ratio · multi stage gearbox
Gear
Final Drive Ratio Calculator
Overall drive ratio from gearbox and differential, with road speed at any engine RPM.
overall ratio = gearbox ratio × final dri…
Also called differential ratio · axle ratio calculator
Key gear formulas
| Gear Ratio | ratio = driven teeth ÷ driving teeth |
|---|---|
| Gear Diameter | pitch diameter = module × teeth · OD = d + 2m |
| Gear Module | module = pitch diameter ÷ number of teeth = 25.4 ÷ DP |
| Compound Gear Ratio | total ratio = ratio₁ × ratio₂ × ratio₃ … |
| Final Drive Ratio | overall ratio = gearbox ratio × final drive ratio |
Gear questions
Does a higher gear ratio mean more speed?
No — a higher numeric ratio means more torque and lower output speed. Overdrive ratios are below 1.