Calculate Robot Speed and Odometry

A free browser-based calculator for wheeled mobile robot kinematics. Enter wheel diameter, RPM (or motor RPM with gear ratio), and encoder CPR to instantly get linear speed in m/s, km/h and mph, odometry resolution in ticks per metre and distance per tick, and a reverse solver to find the RPM needed for a target speed.

How to Use the Robot Speed Calculator

Enter wheel diameter

Type the wheel diameter and choose the unit (mm, cm or inch). The circumference is calculated instantly.

Set RPM or motor speed

Switch to "Wheel RPM" for direct input, or use "Motor RPM + Gear Ratio" mode if you know the motor speed and gearbox reduction.

Add encoder CPR for odometry

Enter the total counts per wheel revolution. For quadrature encoders multiply PPR by 4; for motor-shaft encoders also multiply by the gear ratio.

Use the reverse solver

Type a target speed in m/s, km/h or mph to find out the exact wheel RPM (and motor RPM if a gear ratio is set) needed to reach it.

Compute linear speed and encoder ticks for any wheeled mobile robot

Quick Presets

Robot Parameters

Wheel Diameter

Wheel Speed (RPM)

RPM

Encoder Counts per Wheel Revolution (CPR)

CPR

For a quadrature encoder: CPR = PPR × 4. If encoder is on the motor shaft: CPR = motorCPR × gearRatio.

Encoder note: A quadrature encoder with N pulses per revolution produces 4N counts (CPR = 4 × PPR). If your encoder sits on the motor shaft before the gearbox, multiply its CPR by the gear ratio to get counts per wheel revolution.

Features

Supports mm, cm and inch wheel diameter — converts automatically Motor RPM + gear ratio mode computes wheel RPM and required motor speed Odometry: ticks per metre and distance per tick from encoder CPR Reverse solver: enter a target speed to get the required wheel and motor RPM Three presets for small (65 mm), mid (120 mm) and large (200 mm) robots Inputs saved to localStorage — restores your last session on return

FAQ

How is linear speed calculated?

Linear speed = wheel circumference × RPM / 60. Circumference = π × diameter. For a 100 mm wheel at 60 RPM: π × 0.1 m × 60 / 60 ≈ 0.314 m/s.

What is CPR and how does it differ from PPR?

PPR (Pulses Per Revolution) is the number of pulses on a single channel. A quadrature encoder has two channels 90° apart, giving 4 edges per pulse cycle, so CPR = PPR × 4. Enter the final counts per wheel revolution in this calculator.

My encoder is on the motor shaft — what CPR should I enter?

Multiply the encoder CPR (or PPR × 4) by the gear ratio. For example, a 500 CPR encoder with a 20:1 gearbox gives 10 000 counts per wheel revolution.

What is "ticks per metre"?

Ticks per metre = CPR / wheel_circumference_m. It tells the robot controller how many encoder counts correspond to one metre of travel — a key parameter for odometry and PID distance control.

What wheel diameter unit should I use?

Use whichever unit your datasheet provides. The calculator accepts mm, cm and inches and converts all results to SI (metres) internally.

💡 Want us to improve this tool just for you?

We can — and it's free! Just send us a quick message with your idea. If you'd like to discuss it in detail, leave your email and we'll get back to you. You can stay anonymous.

How do you rate this tool?

Thank you for your rating!

Change my rating

Want to leave a comment?

Want to share more? Leave a comment!

Thank you! Your comment will appear after moderation.

Who is this tool for?

Published 18 May 2026 Updated 21 May 2026