Calculated Results
These results appear after you press the calculate button.
Design Summary
Performance Notes
Current, Flux, and Energy Trend
Calculator Inputs
Example Data Table
These examples show how the calculator summarizes typical design inputs and estimated outputs.
| Mode | Inductance | Avg Current | Ripple | Ae | Aw | Bmax | Turns | Gap | Wire Ø | Copper Loss | Fill |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Manual | 100 µH | 5.0 A | 2.0 A | 125 mm² | 180 mm² | 0.25 T | 20 | 0.628 mm | 1.266 mm | 0.499 W | 34.95% |
| Buck Derived | 30 µH | 5.0 A | 2.0 A | 125 mm² | 180 mm² | 0.25 T | 6 | 0.188 mm | 1.266 mm | 0.150 W | 10.49% |
| Manual | 220 µH | 8.0 A | 3.0 A | 210 mm² | 320 mm² | 0.28 T | 36 | 1.555 mm | 1.642 mm | 1.818 W | 56.72% |
Formula Used
Inductance setup
Manual mode: Use the target inductance entered by the user.
Buck mode: L = ((Vin - Vout) × D) / (fs × ΔI), where D = Vout / Vin when duty is left blank.
Current calculations
Ipk = Iavg + (ΔI / 2)
Irms = √(Iavg² + (ΔI² / 12))
Turns and flux density
Nmin = (L × Ipk) / (Bmax × Ae)
N = ceil(Nmin)
Boperating = (L × Ipk) / (N × Ae)
Approximate air gap
g ≈ (μ0 × N² × Ae) / L
This approximation assumes a gapped design where gap reluctance dominates the magnetic path.
Wire and copper loss
Awire = Irms / J
Wire diameter = √(4 × Awire / π)
Wire length = N × MLT
Rdc = ρ × Wire length / Awire
Pcu = Irms² × Rdc
Stored energy and fill ratio
Energy = 0.5 × L × Ipk²
Fill ratio = (N × Awire) / (Aw × Ku)
How to Use This Calculator
- Choose manual mode if you already know the required inductance, or choose buck mode to derive inductance from converter conditions.
- Enter average current, ripple current, and realistic core geometry values from a datasheet.
- Set a conservative flux-density limit for your material and a practical current density for your winding approach.
- Press the calculate button to generate the results section above the form.
- Review turns, gap, flux density, wire diameter, loss, and fill ratio together rather than relying on a single output.
- Use the graph to inspect how flux density and stored energy rise with current.
- Export the summary with the CSV or PDF buttons when you want a saved design snapshot.
- Confirm the design with manufacturer data, thermal limits, fringing effects, and AC loss checks before production.
FAQs
What does this inductor design calculator estimate?
It estimates inductance, turns, air gap, peak flux density, wire size, copper resistance, copper loss, stored energy, fill ratio, and related magnetic design checks.
Why is the air gap important in a practical design?
The air gap stores most of the magnetic energy and prevents early saturation. In many power inductors, the gap dominates magnetic reluctance and strongly controls inductance.
Why does the calculator use peak current for turns?
Peak current sets the highest flux density in the core. Designing from average current alone can underestimate turns and push the core too close to saturation.
Can this tool pick an exact commercial core for me?
No. It gives engineering estimates. You should still compare the results with manufacturer core data, AL values, thermal curves, bobbin limits, and winding constraints.
What does fill ratio tell me?
Fill ratio compares required copper area with usable window area. Higher values mean the winding is harder to fit and may require different wire, fewer turns, or a larger core.
Is copper loss the only heating source?
No. Core loss, skin effect, proximity effect, fringing, and temperature rise also matter. This calculator mainly estimates DC copper loss for an early design pass.
How is wire diameter estimated here?
The calculator derives conductor cross section from RMS current and chosen current density, then converts that area into an equivalent round wire diameter.
Can I use this for toroids, ferrites, and powder cores?
Yes, for preliminary sizing. Results are most accurate when you enter realistic core area, window area, path length, and a suitable flux-density limit for your material.