Buck Converter Calculator

Written by Great Medico

Updated September 25, 2026 •2 min read

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A fast buck converter estimate is valuable only when the setup is clear. A quick circuit result is most useful when you can trace it back to the exact voltage, current, impedance, frequency, and topology assumed by the formula. The sections below show exactly what this page calculates, how to enter the data, and where the simplified model stops.

What this calculator does

The calculator isolates the relationship between Input voltage (Vin), Output voltage (Vout), Switching frequency (fsw) and duty cycle. That makes it useful for testing how one input changes the answer without mixing in unrelated assumptions.

How to use it

Fill in Input voltage (Vin), Output voltage (Vout), Switching frequency (fsw), Maximum ripple current (Iripple) exactly as defined on the page. After calculating, change one influential input slightly and confirm that the result moves in the direction predicted by the equation; this is a quick unit and setup check.

How the calculation works

For an ideal buck converter, D = Vout/Vin. The page estimates inductance as L = (Vin−Vout)D/(fsw·ΔI) from switching frequency and allowed inductor ripple current.

Example

With the default setup (Input voltage (Vin) = 24 V; Output voltage (Vout) = 12 V; Switching frequency (fsw) = 100 kHz; Maximum ripple current (Iripple) = 1 A), the page reports duty cycle of 50 %. Once this baseline matches, change only one quantity at a time so you can see which variable is controlling the result.

How to interpret the result

The duty cycle belongs to the ideal relationship shown above. Keep voltage, current, frequency, impedance, duty cycle, and component units consistent, then compare the result with real component limits rather than using it as the limit itself.

Limitations and notes

Real circuits include switch and diode losses, ESR/ESL, ripple, tolerances, thermal limits, control-loop behavior, transients, electromagnetic interference, and manufacturer derating that ideal equations may not capture. Before carrying the number into a design or report, confirm Input voltage (Vin), Output voltage (Vout), the unit system, and the model assumptions. Extra decimal places do not compensate for an input that represents the wrong physical quantity.