Toroidal inductor calculator
Estimate turns, winding envelope, copper usage and DC resistance from core and wire parameters.
1. Design goals
Example parameters are ready to edit.
Installation limits: Ø ≤ 100 mm · H ≤ 100 mm · Hole ≥ 2 mm
2. Core and inductance
Select a manufacturer, material series and model, or search across manufacturers. Missing parameters and bias curves are not inferred. (6420)
Matching models: 1339 · Showing first 100; refine search for more
PDF-checked parameters · Selected model source
KDA · KS107-060A · 27.7 × 14.1 × 9.45 mm · AL 59
View / edit core parameters
Changing core dimensions or AL switches to custom; no bias curve is assumed from a material name.
3. Winding and operating conditions
Insulated diameter is an estimate: bare diameter + 0.06 mm. Confirm with the wire supplier.
Parallel wires, leads and winding settings
4. Design estimate
Geometry: fits current space limits
Bias data: Typical curve available · Temperature: Not assessed
Target → integer-turn inductance: 68 → 76.46 μH
Resistance, losses and all results
- Layers
- 1
- Zero-bias inductance
- 76.46 μH
- AL tolerance range
- 70.35 – 82.58 μH
- Inductance at working current
- ≈ 70.86 μH (min ≈ 65.19 μH)
- Flat envelope L × W × H
- 29.42 × 29.42 × 11.17 mm
- Remaining hole
- 12.38 mm
- Installed wire (all strands)
- 1.37 m
- Wire with allowance
- 1.44 m
- Copper mass
- 6.16 g
- Core + copper mass
- 25.56 g
- DC resistance at 20°C
- 46.89 mΩ
- DC resistance at temperature
- 54.27 mΩ
- DC copper loss
- 0.488 W
- Current-density reference
- 2.01 A
- Actual current density
- 5.97 A/mm²
Integer turns are rounded up using minimum AL. Loaded-target mode searches integer turns using the typical bias curve. Finished wire diameter must be checked against your wire supplier.
Evidence and winding feasibility
Core parameters from manufacturer catalog; Turns, resistance and copper mass are calculated; envelope and packing are geometric estimates. Parallel wires are side by side; leads, mounts and lead exits are excluded.
AL tolerance: 8% · Core mass: 19.4 g · Finished wire diameter: Provisional
Meets geometry and space limits; winding process requires verification.
Target → integer-turn inductance: 68 → 76.464 μH · Flat L×W×H: 29.42 × 29.42 × 11.17 mm
Operating / current-density reference: 3 / 2.011 A. Reference current is not a current rating.
Bias-curve current: 5.906 A · — means no valid model-specific curve. This is not a thermal current rating.
Calculation assumptions
Geometric estimate: concentric layers, side-by-side equal parallel strands, rectangular core cross-section and even coverage. Flat dimensions exclude leads, bobbins, mounting and manufacturing clearance. Wire weight is copper only; total excludes enamel and added insulation. Equal current sharing is assumed.
Current-density reference is not a rated current. Thermal rise, AC copper loss, core loss and insulation ratings are not verified. Validate with a physical sample at the actual frequency, ripple and cooling conditions.
Bias results use a digitized typical KDA curve (1–1,000 Oe, approximate log interpolation), not a guaranteed minimum curve. AL tolerance is applied independently; loaded minimum is a planning estimate. No extrapolation. Zero-bias AL assumes the manufacturer test conditions; uneven winding may differ.
Manufacturer data and method
Saved designs and comparison
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| Design | L / I | Turns/layers | OD×H / hole mm | Wire m / copper g | DCR Ω / DC loss W | Loaded L μH | Actions |
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High-frequency and steady-state thermal estimate
Single-winding storage/filter inductors with triangular ripple; not common-mode chokes or transformers. AC resistance factor, core loss density and thermal resistance require manufacturer, simulation or measured evidence.
Evidence has not been confirmed.
Copper skin depth: 0.225 mm · Ripple RMS: 0 A
At entered winding temperature: copper including ripple / core / total loss: 0.488 / — / — W
Steady-state temperature: — °C
Total temperature requires evidence, core loss and thermal resistance. Model includes copper resistance feedback with constant core loss and thermal resistance. Skin depth does not model proximity effect. Results are not a current rating or safety certification.