Analyze coils using geometry, turns, and permeability. Review energy, reactance, voltage, and timing in seconds. Get reliable results, exports, formulas, and guidance for design.
Use the responsive grid below. Large screens show three columns, medium screens show two, and mobile shows one.
The calculator is built around the magnetic circuit estimate for self inductance:
L is self inductance in henries, μ₀ is free space permeability, μᵣ is relative permeability, N is turns, A is cross sectional area, and l is magnetic path length.
Solenoid: A = π(d/2)² and l ≈ coil length. This works best when the coil is long compared with its diameter.
Toroid: A = (rₒ − rᵢ)h and l = 2πrₘ, where rₘ is the mean radius. This suits toroidal cores with rectangular cross sections.
Custom path: enter your own magnetic path length and area when you already know the effective core dimensions.
Derived values use standard relations: XL = 2πfL, E = 0.5LI², τ = L/R, and V = L(dI/dt).
| Case | Model | Turns | μr | Geometry | Calculated L |
|---|---|---|---|---|---|
| Example 1 | Solenoid | 500 | 1 | Diameter 25 mm, Length 80 mm | 1.927657 mH |
| Example 2 | Toroid | 120 | 150 | Inner radius 15 mm, Outer radius 25 mm, Height 10 mm | 2.16 mH |
| Example 3 | Custom path | 800 | 200 | Path length 180 mm, Area 120 mm² | 107.233029 mH |
For high accuracy hardware work, compare these results with measured inductance, manufacturer core data, or a field solver. The calculator is strongest as a fast engineering estimate, not as a final verification method.
Self inductance measures how strongly a coil resists changes in its own current by storing magnetic energy and producing an opposing induced voltage.
Permeability describes how easily magnetic flux forms in a material. Higher relative permeability usually raises inductance sharply when geometry and turn count stay fixed.
Use the solenoid model for straight cylindrical coils where the magnetic path is approximated by the winding length and the cross section is circular.
Use the toroid model for ring shaped cores. It usually gives tighter flux containment and often reduces external magnetic field leakage.
Those values are optional operating conditions. They let the tool estimate stored magnetic energy, inductive reactance, and induced voltage alongside inductance.
No. Real coils can differ because of fringing, core saturation, winding spacing, material tolerance, temperature, and frequency dependent losses.
The RL time constant needs resistance. If resistance is zero, the tool still calculates inductance but does not report a finite time constant.
Yes, as long as you provide a reasonable relative permeability and remember that strong saturation or nonlinear behavior can reduce accuracy.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.