Duty Cycle Calculator — PWM Pulse Width & Frequency
Calculate the duty cycle of any pulse-width modulated (PWM) signal from the pulse width and period, ON and OFF times, or frequency and duty cycle percentage. Also computes frequency, period and the average voltage.
Input mode
Time unit
ms
ms
V
Fraction of the period the signal is in the active (HIGH) state
- 1
Pulse ratio
2 ÷ 10 = 0.2 - 2
Duty cycle
0.2 × 100 = 20
How does this calculator work?
Duty cycle = ON time ÷ Period × 100%. A 2 ms pulse in a 10 ms period is 20% duty cycle at 100 Hz. Average voltage of a PWM signal equals duty cycle × peak voltage. Enter pulse width, period or ON/OFF times in any unit — get frequency and average voltage instantly.
Formula
How this is calculated
Duty cycle describes the proportion of time a periodic signal spends in its active (HIGH or ON) state over one full cycle. A 25% duty cycle means the signal is high for a quarter of the period; 50% is a symmetric square wave; 100% means the signal is permanently on. The formula is simply D = t_on / T, where t_on is the pulse width and T is the period (one full ON + OFF cycle). Frequency is the reciprocal of the period.
PWM (pulse-width modulation) is used everywhere: motor speed control, LED dimming, servo positioning, audio generation and power-supply regulation. By varying the duty cycle, you effectively vary the average power delivered to a load — a motor runs slower at 20% duty cycle than at 80%, even though the peak voltage is the same. The average voltage seen by a resistive load equals the duty cycle fraction of the peak supply voltage.
This calculator accepts three input modes: (1) pulse width and total period, (2) ON time and OFF time separately, or (3) frequency plus duty cycle percentage (useful when you know the target frequency and want to compute timing values). All three mode yield the same set of output values.
Frequently asked questions
A 50% duty cycle means the signal is HIGH for exactly half the period and LOW for the other half — a perfect square wave. Many clocks, oscillators and motor control circuits use 50% as a default or target.
For a resistive load, average power P_avg = D × P_peak, where D is the duty cycle fraction and P_peak = V_peak² / R. For inductive loads (motors, solenoids) the relationship is more complex but duty cycle still approximately controls average energy delivery.
Standard RC servos use a 50 Hz PWM signal (20 ms period). The pulse width typically ranges from 1 ms (0° or one extreme) to 2 ms (180° or the other extreme), corresponding to 5–10% duty cycle. The servo reads the pulse width — not the duty cycle directly — to set position.
Also known as
TG we-Calculate Editorial Team. (2026). Duty Cycle Calculator — PWM Pulse Width & Frequency [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/duty-cycle-calculator
TG we-Calculate Editorial Team. "Duty Cycle Calculator — PWM Pulse Width & Frequency." TG we-Calculate. 2026. https://we-calculate.com/calculator/duty-cycle-calculator.
TG we-Calculate Editorial Team, "Duty Cycle Calculator — PWM Pulse Width & Frequency," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/duty-cycle-calculator
@misc{wecalculate_duty_cycle_calculator, title = {Duty Cycle Calculator — PWM Pulse Width & Frequency}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/duty-cycle-calculator}}, year = {2026}, note = {TG we-Calculate} }
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