Buck Inductor Calculator
Size a buck inductor across an input voltage range. Compare standard values, ripple, peak current and RMS current with inductance tolerance.
Calculations run locally. Save is device-only; sharing includes the entered values.
Operating conditions
Units are fixed beside each field: V, A, kHz, µH, mΩ and °C.
Vin max ≥ Vin min > Vout > 0; load, frequency and L > 0; ripple target 0–200% (exclusive); tolerance 0–100% (100 excluded).
Calculation results
- Required minimum effective L
- 6.4815 µH
- Nominal L allowing for tolerance
- 8.1019 µH
- Minimum L from tolerance
- 8 µH
- CCM boundary load
- 0.36458 A
- Peak current
- 3.3646 A
- RMS current
- 3.0074 A
Ripple across input range: 0.72917–0.72917 A
Duty-cycle range: 41.667–41.667%
Compare standard inductances
| Nominal L | Minimum L from tolerance | Inductor ripple (peak-to-peak) | Peak current | RMS current | Mode | Ripple target | Use |
|---|---|---|---|---|---|---|---|
| 5.6 µH | 4.48 µH | 1.3021 A | 3.651 A | 3.0235 A | CCM | Exceeded | |
| 6.8 µH | 5.44 µH | 1.0723 A | 3.5362 A | 3.0159 A | CCM | Exceeded | |
| 8.2 µH | 6.56 µH | 0.88923 A | 3.4446 A | 3.011 A | CCM | Met | |
| 10 µH | 8 µH | 0.72917 A | 3.3646 A | 3.0074 A | CCM | Met | |
| 12 µH | 9.6 µH | 0.60764 A | 3.3038 A | 3.0051 A | CCM | Met |
Model & formulas
Ideal steady-state, nonnegative CCM model with fixed frequency. Worst ripple occurs at maximum input voltage and minimum L from tolerance. DC bias, temperature-related inductance change, controller limits, startup and transients are not modeled. Check the controller datasheet and real waveforms.
ΔI = Vout × (1 − Vout/Vin) / (f × Lmin)
Lmin = Lnom × (1 − tolerance/100)
Ipeak = Iout + ΔI/2
Irms = √(Iavg² + ΔI²/12)