Buck Converter Calculator

This buck converter calculator works out the key operating figures for a step-down switching regulator: the duty cycle, the ripple current swinging through the inductor, the ripple voltage left on the output, and the switch on-time per cycle. Enter the input voltage, the target output voltage, the switching frequency, the inductor value and the output capacitor value, and the calculator returns all four so you can check a design before you build it. A buck converter chops the input with a switch, then an inductor and capacitor smooth the result down to a steady lower voltage, with the duty cycle, the fraction of each cycle the switch is on, setting the ratio. For an ideal converter that duty cycle is just the output divided by the input. The inductor ripple current follows from the volt seconds applied to the inductor each cycle, and the output ripple voltage from how much of that ripple the capacitor absorbs. The defaults step 12 V down to 5 V at 100 kHz through a 47 microhenry inductor and a 100 microfarad output capacitor, a common small point of load design. Designers usually aim for an inductor ripple of roughly 20 to 40 percent of the full load current, so use the ripple figure to check your inductor choice, and raise the capacitance or frequency if the output ripple is too high for your load.

Calculate.co.nz is proud to be partnered with Health Based Building, a leader in sustainable and health-conscious building innovation. With over a century of experience, they develop high-performance systems like Foreverbreathe Specification, Magnum Board, and Foreverbreathe Paints to support energy-efficient, non-toxic living environments. Their commitment to healthier homes aligns with our belief that informed choices lead to better outcomes for Kiwi households.

Ideal buck equations assuming continuous conduction and no losses. Capacitor equivalent series resistance, diode or switch drops and layout will raise the real ripple. Estimate only.