Calculate a measured torque ratio, estimate geared output torque and speed, or reverse-solve required input torque with unit conversion and gearbox efficiency.

Compare nonnegative torque magnitudes using a common unit.

Input speed (optional)

Blank omits speed and mechanical-power comparisons.

Related Calculators

Torque Ratio Formula

The following formula is used to calculate the torque ratio:

TR = (OT) / (IT)

Variables:

  • TR is the torque ratio (dimensionless)
  • OT is the output torque (newton-meters)
  • IT is the input torque (newton-meters)

To calculate the torque ratio, divide the output torque by the input torque.

What is a Torque Ratio?

Torque ratio is output torque divided by input torque, using consistent units. A ratio above 1 means greater output torque; a ratio below 1 means less output torque. A measured torque ratio alone does not determine actual output speed, efficiency, force at a particular lever arm, or safe load capacity.

How to Calculate Torque Ratio?

The following steps outline how to calculate the Torque Ratio.

  1. First, choose Ratio from measured torques and enter the input torque (IT) in any listed torque unit.
  2. Next, enter the output torque (OT). The calculator converts both torques to consistent units.
  3. Next, gather the formula from above: TR = OT / IT.
  4. Finally, calculate the Torque Ratio (TR).
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem:

Use the following variables as an example problem to test your knowledge.

input torque (IT) = 50 Nm

output torque (OT) = 200 Nm. The measured torque ratio is 200 ÷ 50 = 4:1.