Enter values and press Calculate.
Uses the same V, I, tr, tf as the calculator above — switch tabs, run a calculation, then view how loss scales with frequency.
Every time a power switch turns on or off, it briefly carries both significant voltage and significant current at the same time as they cross over — and V×I during that crossover is instantaneous power, dissipated as heat. Because this happens on every switching cycle, the resulting switching loss grows directly with frequency, unlike conduction loss which depends only on RMS current. This is the fundamental power-electronics trade-off: higher switching frequency shrinks passive components (see the Magnetics section) but raises switching loss.
| Quantity | Formula |
|---|---|
| Crossover energy per event | Esw = ½×V×I×(tr+tf) |
| Switching power | Psw = Esw × fsw |
| Reverse recovery loss | Prr = Qrr × V × fsw |
| Total switching-related loss | Psw(total) = Psw + Prr |
This model uses the simplified linear crossover approximation — treating voltage and current as ramping linearly during tr and tf — which is the standard first-pass estimate used across the industry. Real waveforms are affected by parasitic inductance, gate drive strength, and the device's own capacitances, so measured loss is often somewhat different; this calculator gives the right order of magnitude and correct frequency scaling.
It is the energy lost every time a power switch turns on or off, caused by voltage and current briefly overlapping during the transition. Unlike conduction loss, it occurs once per switching cycle and so scales directly with switching frequency.
The linear-crossover approximation gives Esw = ½×V×I×(tr+tf), where V and I are the switched voltage and current, and tr, tf are the rise and fall (crossover) times.
Multiply the per-event energy by the switching frequency: Psw = Esw×fsw, since the switch produces one such energy loss per cycle.
Each switching transition wastes a fixed amount of energy (for given V, I, and speed), so switching more often per second directly multiplies the total power lost — this is the fundamental trade-off against smaller magnetics at high frequency.
Use a stronger/faster gate driver to shorten tr and tf, choose a device with lower capacitances (or a wide-bandgap device like SiC/GaN), reduce the switched voltage or current where possible, or use soft-switching (ZVS/ZCS) topologies that largely eliminate the overlap.
When a diode turns off, stored charge (Qrr) must be swept out before it blocks voltage, causing a brief reverse current spike. This dissipates Prr=Qrr×V×fsw and can rival or exceed the switch's own switching loss.
They have far smaller parasitic capacitances and, for SiC diodes, negligible reverse recovery charge, so their crossover times are a fraction of silicon's — letting designers push to much higher frequencies for the same loss budget.
It captures the correct order of magnitude and the linear frequency scaling that matters for design trade-offs. Real switching is nonlinear (affected by Miller plateau, parasitic inductance and gate drive), so datasheet or measured Eon/Eoff values are more accurate when available.
Hard switching (what this calculator models) has full voltage and current overlapping at each transition. Soft-switching topologies (like the LLC resonant converter) arrange for voltage or current to be near zero during the transition, dramatically cutting switching loss.
If the manufacturer provides tested Eon and Eoff values at your operating conditions, those are more accurate than the linear approximation and should be preferred; use this calculator for early estimates or when only rise/fall times are known.
Yes, directly. A larger gate resistor slows the gate charge/discharge, increasing tr and tf and therefore switching loss — see the MOSFET Gate Resistor calculator for that trade-off against ringing and EMI.
They simply add: total device loss = conduction loss + switching loss (+ any reverse recovery loss from an associated diode). See the MOSFET Power Loss calculator for a combined breakdown specific to MOSFETs.
MOSFET Power Loss • MOSFET Gate Resistor • Junction Temperature • All Calculators