Motor & Wheel Sizing Calculator

Choosing drive motors by guesswork usually ends in one of two ways: a robot that cannot climb the ramp at the loading dock, or motors twice as large and expensive as they needed to be. The Motor & Wheel Sizing Calculator replaces the guess with the physics.

What it calculates

• The forces on the robot: rolling resistance on your surface, gravity on the steepest slope, and the force to accelerate.
• The continuous and peak torque each drive motor must deliver, with your safety factor.
• The wheel speed at top speed, the output power per motor and the battery current.
• A traction check that tells you when the wheels would slip before the motors run out of torque.
• A check of a real motor from its datasheet, drawn as a torque-speed line against your operating points.

Who it is for

Anyone designing a wheeled robot: a student rover, a delivery robot, a lawn mower, an agricultural platform. The defaults describe a 20 kg indoor robot so you can see sensible numbers straight away.

How it is checked

Every result is reproduced by hand in the tool's worked example, step by step, so you can follow and verify the method.

Open the Motor & Wheel Sizing Calculator. The guides below cover motor sizing in depth, the forces on a robot, reading motor datasheets, choosing wheels, and choosing between brushed, brushless and stepper motors.