Gear Train Calculator
Speed ratio is the product of driven teeth over the product of driving teeth: 20/60 then 15/45 gives 9:1, so 1200 rpm becomes 133.333 rpm.
One number per meshing pair, in order.
Output torque for a loss-free train; 0 to skip.
133.333333333333 rpm
Full answer, then cut to fewer decimals (not rounded):
- 133.333333333333 rpm
- 133.33333333333 rpm
- 133.3333333333 rpm
- 133.333333333 rpm
- 133.33333333 rpm
- 133.3333333 rpm
- 133.333333 rpm
- 133.33333 rpm
- 133.3333 rpm
- 133.333 rpm
- 133.33 rpm
- 133.3 rpm
- Speed ratio N₁/Nout = Π driven ÷ Π driving
- 9
- Train value = 1 / speed ratio
- 0.111111
- Direction (external gears)
- same as input
Step-by-step solution
- Speed ratio = (60 × 45) ÷ (20 × 15) = 9
- Nout = 1200 ÷ 9 = 133.333 rpm
Gear Train Formula
N₁/Nout = Π driven teeth ÷ Π driving teeth
train value = 1/speed ratio
Worked Example
A compound train 20/60 then 15/45 driven at 1200 rpm:
- Speed ratio = (60 × 45) ÷ (20 × 15) = 9
- Nout = 1200 ÷ 9 = 133.333 rpm
Train value = 1 / speed ratio: 0.111111 · Direction (external gears): same as input
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Frequently asked questions
Do idler gears change the speed ratio?
No, an idler only reverses the direction of rotation; the ratio depends on the first driver and last driven gear.
How is torque related to speed ratio?
Without losses, power is constant, so output torque = input torque × speed ratio.
Sources
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Gear Train Calculator. Retrieved October 25, 2026, from https://scientificconverters.com/calculators/gear-train-calculator/
IEEE
Scientific Converters, "Gear Train Calculator," scientificconverters.com. Accessed: Oct. 25, 2026. [Online]. Available: https://scientificconverters.com/calculators/gear-train-calculator/