How to Calculate the Duty Cycle of a Square Wave
- 1). Measure the length of the cycle of the square waveform with your ruler. If you are using graph paper or an oscilloscope, count the number of squares occupied by the waveform on the grid. The cycle is the total length of the waveform and can be found by measuring the distance from the first zero-crossing, which is the point where the waveform meets the 0 coordinate on the Y-axis, to the third zero-crossing. Write the length of the cycle down on a piece of paper.
- 2). Measure the portion of the waveform above the X axis with your ruler or by counting the number of squares occupied on your graphing paper or oscilloscope. The X axis is the horizontal line that crosses through the X and Y coordinates 0, 0 on a graph. Write down the measurement. This is the length of the duty cycle.
- 3). Divide the length of the duty cycle by the length of the square wave's cycle. Multiply the result by 100 to convert the number to a percentage. If the result is equal to 50 percent, the waveform is a square wave and the duty cycle is 50 percent. If the result is above or below 50 percent, the waveform is a rectangle wave.