Motor Control Calculators
18 free calculators with formulas and worked examples.
DC motor speed, stepper motor resolution, BLDC power, servo torque, gear ratios, PID tuning, H-bridge selection, and motor efficiency calculators.
DC Motor
Calculate DC motor speed, torque, power, and efficiency from electrical parameters
Stepper Motor
Calculate stepper motor speed, step frequency, and travel per revolution
BLDC Motor
BLDC motor calculator: enter Kv rating and voltage to get no-load RPM, stall torque, max efficiency point, and propeller thrust. Supports drone, RC, and industrial winding calculations.
Servo Motor
Calculate servo motor torque, speed, efficiency, and back-EMF from electrical and load parameters.
Gear Ratio
Calculate gear ratio, output speed, torque multiplication, and power transmission efficiency for gear trains.
PWM Motor Speed
Convert PWM duty cycle to effective motor voltage, calculate no-load speed and stall current for DC motor PWM control.
Torque Converter
Convert torque between Newton-metres, pound-feet, pound-inches, oz·in, kg·cm and dyne·cm — covers all motor datasheet units.
Motor Efficiency
Calculate motor efficiency, power losses, and heat dissipation from electrical input and mechanical output measurements.
Motor Slip
Calculate induction motor slip, synchronous speed, slip frequency, and rotor speed for AC induction motors.
Motor Inrush
Calculate motor inrush current, voltage drop during startup, and I²t value for fuse/breaker selection.
Motor Heat
Calculate motor heat dissipation, temperature rise, and operating temperature from input power and efficiency.
Encoder Resolution
Calculate encoder counts per revolution, angular resolution, and maximum frequency for quadrature and single-channel encoders.
Starting Torque
Calculate DC motor starting (stall) torque, stall current, no-load speed, and peak power at startup.
Motor Battery Life
Calculate battery runtime for motor-driven systems accounting for motor current draw, efficiency, and depth of discharge.
Winding Resistance
Calculate motor winding resistance at operating temperature using the copper temperature coefficient of resistance.
H-Bridge
Calculate H-bridge MOSFET requirements including peak current, conduction losses, and minimum current rating for DC motor drivers.
Driver Power
Calculate motor driver IC or discrete MOSFET power dissipation including conduction loss and switching loss at a given PWM frequency.
PID Tuning
Calculate PID controller gains using the Ziegler-Nichols open-loop (reaction curve) method from process gain, dead time, and time constant.
About Motor Control Calculators
Motor control electronics spans the interface between digital control systems and electromechanical actuators — DC motors, stepper motors, BLDC motors, and servo drives. Each motor type presents a different control challenge and set of design tradeoffs.
DC motors follow a simple model: torque is proportional to armature current, speed is proportional to back-EMF (and thus terminal voltage minus I·R_a drop). PWM control varies the average voltage by switching at high frequency, achieving smooth speed control at high efficiency. H-bridge drivers implement four-quadrant operation (forward, reverse, brake, coast) using four power MOSFETs. Selection requires calculating peak current, continuous RMS current, and thermal dissipation at worst-case duty cycle.
Stepper motors divide rotation into discrete steps (typically 1.8°/step = 200 steps/revolution) using two or more phase windings. Microstepping drivers interpolate between full steps by proportioning current between phases, reducing vibration and improving positional resolution to 1/256 step or better. The trade-off is reduced torque at high microstep counts. Resolution calculators convert steps/rev and lead screw pitch to linear positioning accuracy.
BLDC motors use electronic commutation via Hall sensors or back-EMF zero-crossing detection, achieving higher power density and efficiency than brush DC motors. PID tuning calculators — using Ziegler-Nichols or IMC methods — set proportional, integral, and derivative gains for position and velocity loops. Battery runtime calculators account for motor efficiency, drivetrain losses, and battery discharge characteristics to predict system endurance.