Calculate duty cycle percentage and frequency from pulse width and period.Both pulse width and period must be in milliseconds.Essential for PWM signals, servo control, and power electronics.
Last updated: March 2026 | By Patchworkr Team
Time the signal is HIGH (in milliseconds)
Complete cycle time (HIGH + LOW)
Duty cycle is the percentage of time that a signal is in the "on" or "high" state during one complete period. It's expressed as a percentage from 0% (always off) to 100% (always on). For example, a 25% duty cycle means the signal is HIGH for 25% of the time and LOW for 75% of the time.
Duty cycle is fundamental in Pulse Width Modulation (PWM), which is used extensively in electronics for motor speed control, LED dimming, servo positioning, power regulation, and digital-to-analog conversion. By varying the duty cycle, you can effectively control the average power delivered to a device.
The frequency (measured in Hertz) tells you how many complete on-off cycles occur per second. The relationship is: Frequency = 1 / Period. Higher frequencies are used for smoother motor control and reduced flicker in LED applications, while lower frequencies might be used for heating elements or other applications where switching speed is less critical.
PWM signal: 5ms pulse width, 20ms period:
Duty cycle is the percentage of time the signal is HIGH (0-100%). Frequency is how many complete cycles occur per second (Hz). They're independent - you can have any duty cycle at any frequency.
50% duty cycle = 50% brightness. Higher frequency (>100 Hz) prevents visible flicker. Most LED controllers use 500 Hz to 20 kHz for smooth, flicker-free dimming across the full range.
Higher duty cycle = more average power = faster motor. 50% duty cycle delivers 50% of maximum power. PWM frequency should be above motor's mechanical response (typically 1-20 kHz) to avoid vibration.
Standard servos use 1-2ms pulses in a 20ms period (5-10% duty cycle). 1ms = 0°, 1.5ms = 90°, 2ms = 180°. The 20ms period (50 Hz) is the standard servo refresh rate.
No, duty cycle cannot exceed 100% by definition. If pulse width equals or exceeds the period, the signal is constantly HIGH (100% duty cycle). Pulse width must be ≤ period.
LEDs: 100-20,000 Hz. Motors: 1-20 kHz. Servos: 50 Hz. Heating: 1-10 Hz. Higher frequencies reduce audible noise and electromagnetic interference but may increase switching losses in power electronics.
Duty cycle affects average voltage. A 5V signal at 50% duty cycle delivers an average of 2.5V. However, the peak voltage remains 5V - only the time-averaged power changes.
Dead time is a brief period when both high and low-side switches are off to prevent shoot-through in H-bridges and inverters. It's separate from duty cycle calculations but reduces effective duty cycle slightly.
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