Pulse Width Modulation (PWM) controls power by rapidly switching a digital signal on and off. The duty cycle percentage determines the effective average voltage delivered to the load. This is the standard technique for dimming LEDs, controlling DC motor speed, and regulating power supply outputs.
PWM Parameters
PWM Signal Waveform
Motor Speed Estimate
Estimated DC motor speed: 50% of max RPM
How to Use the PWM Duty Cycle Calculator
This PWM duty cycle calculator converts duty cycle percentage into average output voltage, period, on-time, and off-time. Use it for LED dimming circuits, DC motor speed control, or switching power supply design.
PWM Fundamentals
Average Voltage = Vsupply × (Duty Cycle% / 100). Period (T) = 1 / Frequency. On-time = T × Duty Cycle%. Off-time = T − On-time. A 1kHz PWM signal has a 1ms period. At 50% duty cycle: on-time = 0.5ms, off-time = 0.5ms, average voltage = 50% of Vsupply.
Frequency Selection by Application
LED dimming: use 200Hz or higher to prevent visible flicker (25Hz threshold for human eye, higher for cameras). DC motor control: 1–20kHz — lower frequencies cause audible whine at the switching frequency. Servo motor: 50Hz standard (20ms period). Audio amplifiers: use ultrasonic frequencies (above 20kHz) to keep switching noise out of the audio band.
FAQ
Is this PWM duty cycle calculator free?
Yes, completely free. Calculate PWM parameters for any duty cycle without any account or payment.
Is my data private?
All calculations run in your browser. No data is sent to any server.
What is PWM (Pulse Width Modulation)?
PWM is a digital technique that simulates an analog voltage by rapidly switching a digital signal on and off. The duty cycle (percentage of time the signal is HIGH) controls the effective average output voltage. A 50% duty cycle at 12V produces an average of 6V.
How is average voltage calculated from duty cycle?
Average Voltage = Supply Voltage × (Duty Cycle % / 100). A 75% duty cycle at 24V = 18V average. This is the simplified formula assuming ideal switching — in real circuits, switch losses, inductor effects, and load characteristics affect the actual output.
What PWM frequency should I use?
For LED dimming: 200Hz+ (above flicker threshold, though 1kHz+ is better for cameras). For DC motors: 1–20kHz (lower = audible whine, higher = switching losses). For servo motors: 50Hz is standard. For audio: use frequencies well above the signal bandwidth.
How does PWM control motor speed?
At low duty cycles, the motor receives less average voltage and rotates slower. Speed is approximately proportional to duty cycle for DC motors in the linear region. PWM is more efficient than a series resistor because the motor receives full voltage in pulses rather than a reduced continuous voltage.
What is the difference between frequency and duty cycle?
Frequency determines how fast the signal switches on and off (Hz). Duty cycle determines the proportion of time it is ON vs. OFF. Both parameters are independent — you can have high frequency at any duty cycle. Period = 1/Frequency, On-time = Period × Duty Cycle.