Motor Torque from Current
Calculate the torque produced by a DC motor, T = K_t·I, from the torque constant K_t (N·m/A) and the armature current I. The result, in N·m, shows a DC motor's torque is directly proportional to current — which is why measuring current is the simplest way to estimate (and limit) torque and detect overloads. The torque constant K_t is a motor characteristic (numerically equal to the back-EMF constant K_e in SI units). It is the basis of torque control in servomotors and robotics. Enter the torque constant and the current.
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Motor torque from current
In a DC motor (and in vector-controlled brushless servomotors) there is a beautifully simple, linear relationship between what goes in and what comes out: torque is proportional to current. T = K_t·I, where I is the armature current and K_t is the motor's torque constant (in N·m/A), a fixed characteristic that follows from the physics of the machine (magnetic field, number of turns, geometry). This proportionality has deep, practical consequences. First, it makes current the natural torque sensor: measuring the current the motor draws is the simplest, cheapest and fastest way to know how much torque it is producing — which enables torque control (essential in robotics, where the grip force or the interaction with the environment must be regulated) and overload and collision detection (a current spike reveals that the robot has hit something). Second, it lets firmware limit torque merely by limiting current, protecting the mechanism. An elegant fact: in SI units the torque constant K_t is numerically equal to the back-EMF constant K_e (V·s/rad) — no coincidence, but a consequence of energy conservation (the electrical power K_e·ω·I equals the mechanical power T·ω). K_t appears on the motor datasheet, sometimes as 'torque constant' or inferred from the peak torque and the peak current. Together with the armature resistance and the speed constant, it fully defines the motor's torque-speed curve. In servo control, the current (torque) loop is the innermost and fastest loop, with the speed and position loops built on top of it. Enter the torque constant and the current.
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DC Motor No-Load Speed
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Torque for Angular Acceleration
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Motor Power (Torque × RPM)
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Calculate the rotation speed of a stepper motor, RPM = (pps × 60 × step angle) ÷ 360, from the pulse frequency pps (steps per second) and the motor's step angle (degrees per step). The result, in revolutions per minute, relates the command frequency sent to the driver with the actual shaft speed. Stepper motors lose torque at high speeds, so there is a practical maximum rotation. It is essential for programming axis speeds in 3D printers, CNC and automation. Enter the pulse frequency and the step angle.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.