Inductor Calculator – Guide & Formulas
Determine air-core and magnetic core solenoid inductor values using Wheeler's electromagnetic coil dimensions formula.
Model solenoid electromagnetic components. Input physical characteristics including turns, outer core diameter, coil length, and core magnetic properties to compute estimated inductance in microhenries.
Key Takeaway
Use the free Inductor Calculator to determine air-core and magnetic core solenoid inductor values using wheeler's electromagnetic coil dimensions formula. Get instant results with step-by-step explanations.
How to Use the Inductor Calculator
- Enter the total number of physical coil wire windings (Turns).
- Input physical coil diameter (measured in inches).
- Input the continuous physical coil length (measured in inches).
- Select core material properties (Air, Ferrite, or Soft Iron Powder).
- Instantly read equivalent inductance in microhenries (µH) or millihenries (mH).
The Formula
Variable Definitions
- N: Total number of winding turns
- d / l: Coil diameter and coil physical length measured in inches
- mu_rel: Relative permeability of internal core material compared to air vacuum
Calculating Inductance for an Air-Core Solenoid
Size a coil with 30 turns, 0.5-inch diameter, and 1.2-inch physical length with an air core.
- Step 1: Establish variables: d = 0.5, l = 1.2, N = 30, mu = 1.
- Step 2: Solve numerator: 0.5^2 × 30^2 × 1 = 0.25 × 900 = 225.
- Step 3: Solve denominator: 18 × 0.5 + 40 × 1.2 = 9 + 48 = 57.
- Step 4: Solve final Wheeler inductance: 225 / 57 ≈ 3.947 µH.
Frequently Asked Questions
What is Wheeler's formula?
Wheeler's formula is an empirical approximation for single-layer solenoid coils. It is accurate within 1% for coils where length is greater than 0.4 times diameter.
How does core material affect inductance?
Magnetic core materials like ferrites concentrate magnetic field lines, multiplying system inductance by their relative magnetic permeability rating.