# How to calculate torque required by a motor depending on load?

I want to know whether the torque required by motor depends on load. If it does, then how can I calculate it?

The torque required by the motor is the sum of different actors, for instance it can be the friction in the motor ($T=K_f \dot \phi$), the inertia of the rotor itself ($T=J\ddot \phi$) and then all the loads connected to the motor shaft. You have to include the inertia as well as the damping and stiffness between the different loads.