Duty Cycle Calculator

Calculated Duty Cycle
0%
Total Period: 0

What is Duty Cycle?

In electronics and telecommunications, a duty cycle is the percentage of time that a signal, system, or machine is active or "ON" compared to the total time of one complete cycle. It is a critical concept in Pulse Width Modulation (PWM), which is used to control the power supplied to electrical devices like motors, LEDs, and heaters.

How to Calculate Duty Cycle

The formula for calculating duty cycle is straightforward. You need to know the duration for which the signal is active (On-Time) and the duration for which it is inactive (Off-Time). The sum of these two values represents the Total Period.

The Formula:

Duty Cycle (D) = [On-Time / (On-Time + Off-Time)] × 100%

For example, if an LED is turned on for 2 milliseconds and turned off for 8 milliseconds, the total period is 10 milliseconds. The duty cycle would be (2/10) × 100 = 20%.

Practical Applications of Duty Cycle

  • Motor Control: By varying the duty cycle of the voltage sent to a DC motor, you can precisely control its speed without wasting significant energy.
  • LED Dimming: LEDs are often dimmed by rapidly switching them on and off. A higher duty cycle makes the LED appear brighter to the human eye.
  • Switching Power Supplies: Modern power converters use PWM and duty cycle adjustments to maintain a stable output voltage regardless of the load.
  • Welding Machines: A welder's duty cycle indicates how long it can operate within a 10-minute period before it needs to cool down.

Frequently Asked Questions

Can a duty cycle be over 100%?
No, a duty cycle represents a ratio of a part to a whole; therefore, it cannot exceed 100% (always on) or fall below 0% (always off).

What is the difference between Duty Cycle and Frequency?
Frequency determines how often a cycle repeats per second (measured in Hertz), while the duty cycle determines how much of that cycle is "active" vs. "inactive."

How does duty cycle affect power?
The average power delivered is proportional to the duty cycle. A 50% duty cycle delivers approximately half the power of a 100% duty cycle signal.