Bench tools for builders
Free calculators that answer the questions every robot build starts with: which motor, which battery, which gear ratio. No guesswork, no forum-thread archaeology — and every tool shows the formula it uses.
Open the Motor Sizing Calculator →New tools are added regularly. Bookmark this page — your build will thank you.
Find the torque, RPM and power your robot's drive motors need.
READYHow long will your robot run? Capacity, current draw and C-rating math.
READYMatch motor speed to wheel speed and multiply your torque.
READYSize the servos for your robot arm from length and payload.
READYInteractive simulator — see how Kp, Ki and Kd change your robot's response.
READYTurn encoder counts into mm per tick, robot speed and interrupt load.
READYCan your pack actually deliver the amps? Realistic discharge headroom math.
READYTotal your robot's current draw, then size the BEC, fuse and wire gauge.
READYSteps/mm for belts, screws and wheels — plus a reality check on speed.
READYReal E24 resistor pairs for battery monitors and ADC scaling, with code constants.
READYTurn a target speed and turn rate into left and right wheel RPM — with a reality check.
READYBelt length in teeth, the exact centre distance to build to, and tooth engagement.
READYTorque to lift a load, linear speed, and whether the axis holds without power.
READYTip-over angles, max slope and safe cornering speed from your chassis geometry.
READYkg·cm, N·m, oz·in and lb·ft converted instantly — plus what it actually lifts.
Most robot builds fail at the shopping cart, not the workbench. A motor that stalls on carpet, a battery that dies in eight minutes, a gearbox that turns your "fast" robot into a slow one — all of these are math problems that take thirty seconds to solve before you spend money.
Each tool on this site does one calculation properly, explains the engineering behind it in plain language, and tells you what class of part to look for. Use them, check the math, build better robots.