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Gear Ratio Calculator

Gear ratio, output speed, and output torque — including efficiency factor.

Sketch

Sketch: gearbox with input and output shaftInput with speed n₁, torque M₁ and power P₁; inside the gearbox ratio i and efficiency η; output with n₂, M₂ and P₂. The output shaft is thicker because it carries the higher torque when reducing speed (i > 1).

Enter Input Values

Enter the known values — the rest will be calculated automatically.

min⁻¹
Nm
—
%

Formulas

i = n₁ / n₂
n₂ = n₁ / i
M₂ = M₁ × i × η
P₂ = P₁ × η
i = Gear ratio [-]
n₁/n₂ = Input/output speed [min⁻¹]
M₁/M₂ = Input/output torque [Nm]
η = Efficiency [0–1]

Typical Efficiencies (general literature values)

Spur gearbox97–99%
Planetary gearbox95–98%
Bevel gearbox95–98%
Worm gearbox40–90%

According to the catalog, TEA spiral bevel gearboxes achieve 94–97% efficiency — see Calculating gearbox efficiency.

Note: Efficiency η is entered as a percentage value (e.g. 95 for 95%). For multi-stage gearboxes, individual stage efficiencies are multiplied together.

Notice: The calculation tools provided are intended for initial orientation only and do not replace binding engineering design by qualified specialists. All results must be verified by appropriate engineering calculations before use in safety-critical applications. Technische Antriebselemente GmbH accepts no liability for damages arising from the use of the calculation results.

Want a gearbox proposal for the calculated ratio?

The ratio is fixed — what remains open is the design type, the efficiency and the permissible output load. With your values we will propose specific bevel and worm gearboxes from our range that match the required output speed.

Request a gearbox proposal →

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