RC Snubber Design Calculator

About this calculator

In switching power converters, every trace, pad and component lead has a bit of stray inductance and capacitance, and when a MOSFET or diode switches off abruptly, that parasitic LC network rings — the voltage overshoots and oscillates at a frequency set by the parasitic inductance and capacitance before settling. An RC snubber tames this ringing by adding a resistor in series with a capacitor across the ringing node: the capacitor is sized close to the parasitic capacitance so it can absorb the oscillating energy, and the resistor is sized as R = 1/(2π × f_ringing × C) so it dissipates that energy as heat right at the ringing frequency, damping the oscillation without slowing down the switching edge too much.

Power electronics engineers add snubbers to reduce electromagnetic interference (EMI), protect switching devices from voltage spikes beyond their rated breakdown voltage, and pass EMC compliance testing in designs like flyback converters, motor drives and switch-mode power supplies. This calculator takes your measured ringing frequency and estimated parasitic capacitance and returns the snubber resistor and capacitor values to try first, before fine-tuning on the bench.