Duty cycle is the percentage of one period during which the signal is HIGH (on). A 25% duty cycle means the output is on for one quarter of every cycle. It equals (on-time / period) × 100.

How does duty cycle affect average voltage?

Average voltage = Vcc × (duty cycle / 100). At 100% duty cycle the output equals Vcc; at 0% it is 0 V. This linear relationship is why PWM works so well for analog control with digital outputs.

What is the difference between period and frequency?

Period is the total time for one complete cycle (on + off). Frequency is the reciprocal: f = 1 / T. A 1 kHz PWM signal has a 1 ms period; a 20 kHz signal has a 50 µs period.

What PWM frequency should I use for motor control?

Most DC motor controllers use 1–25 kHz. Below 1 kHz you may hear audible whine; above 25 kHz switching losses in the FETs increase. 10–20 kHz is a common compromise for brushed DC and BLDC applications.

Can duty cycle exceed 100%?

No. Duty cycle is bounded between 0% and 100%. A pulse width equal to the full period is a steady DC-high signal; a zero pulse width is DC-low. Values outside this range indicate an input error.

What is the resolution of a PWM signal?

Resolution is the number of distinct duty-cycle steps a PWM controller can produce, typically expressed in bits. An 8-bit PWM has 256 steps (0–255 counts); a 16-bit PWM has 65,536 steps. Higher resolution gives finer control of output voltage or motor speed.

PWM Duty Cycle Calculator

Name: PWM Duty Cycle Calculator
Availability: InStock
Author: Nham Vu

Enter pulse width and period (or frequency) to instantly compute duty cycle, on-time, off-time, and average output voltage.

PWM Parameters

Supply voltage (Vcc)

Pulse width (on-time)

Period (total cycle)

Summary

Enter pulse width and period (or frequency) to instantly compute duty cycle, on-time, off-time, and average output voltage.

How it works

Enter the supply voltage (Vcc) and select the time unit (µs, ms, or s).
Enter the pulse width (on-time) and the total period, or switch to frequency mode and enter frequency in Hz or kHz.
Click Calculate to see duty cycle %, on-time, off-time, period, frequency, and average output voltage.
Adjust any value and recalculate — the duty cycle bar updates to reflect the new ratio.
Use Reset to clear all fields and start a new calculation.

Use cases

Size PWM parameters for a DC motor speed controller.
Set LED dimming level for a constant-current driver.
Verify switching frequency and duty cycle for a buck or boost converter.
Calculate average output voltage of a PWM-driven H-bridge.
Check on-time and off-time constraints for a MOSFET gate driver.
Teach or learn PWM theory with live numeric feedback.

Frequently Asked Questions

Last updated: 2026-06-11 · Reviewed by Nham Vu