Inductor Saturation Calculator
Check whether your inductor stays out of saturation at peak current, including temperature derating of the saturation current.
About This Calculator
Inductors lose inductance as current approaches the saturation current Isat — typically where inductance drops ~20-30%. Beyond that, ripple current rises sharply and the converter can misbehave. Because Isat also falls with core temperature, this tool derates the datasheet figure by 0.2%/°C above 25 °C and checks peak current against both raw and derated limits.
How to Use
- Enter the datasheet inductance and saturation current at room temperature.
- Enter the true worst-case peak current — DC load current plus half the ripple current.
- Set the expected core temperature (hot spots under the PCB can reach 70-100 °C).
- Check both saturation flags; any '1' means redesign (larger Isat, lower ripple, or better cooling).
Formulas
| Margin | Margin = Isat / I(peak) |
| Derated Isat | Isat(der) = Isat × (1 − 0.002 × (T − 25)), clamped ≥ 60% |
| Headroom | Headroom% = (Isat − Ipeak) / Ipeak × 100 |
Design Notes
Isat is defined at a percentage of nominal inductance (often 20-30% drop) — match that definition when comparing parts.
Core losses also rise with temperature and frequency; saturation is only one failure mode.