How do I use the inductor series and parallel calculator?

Enter the inductance values (in nH, µH, mH, or H) for each coil and specify their connection type (series or parallel). The calculator computes the total inductance and, for parallel configurations, estimates how the input current divides among the branches.

What is the formula for inductors in series?

In a series connection, the total inductance is the sum of the individual inductances: L_eq = L₁ + L₂ + ... + Ln.

What is the formula for inductors in parallel?

In a parallel connection, the total inductance is calculated using the reciprocal sum: 1/L_eq = 1/L₁ + 1/L₂ + ... + 1/Ln.

Can I simulate complex inductor networks?

Yes, the calculator supports nested series and parallel combinations, allowing you to model complex inductor networks and obtain the equivalent inductance and current distribution.

What are the practical applications of this calculator?

This tool is useful for designing filters, power supply chokes, and resonant circuits, helping to avoid manual algebra and providing instant results.

Inductor Series and Parallel Calculator

Input current, A:

This online tool computes the total inductance of a network made of two or more coils connected in series, parallel or any mixed arrangement. Nested branches are supported and the calculator also estimates how the input current divides between branches. Use it for filter design, power supply chokes and resonant circuits to avoid manual algebra and get a clear, instant result.

👉 Add coils and connection blocks in any quantity and at any nesting level. Enter each coil’s value and unit (nH, µH, mH, H) and specify the input current for branch current analysis.

Table of Contents

Calculation formulas

Series connection

$$L_{\text{eq}} = L_1 + L_2 + \dots + L_n$$

Parallel connection

$$\frac{1}{L_{\text{eq}}} = \frac{1}{L_1} + \frac{1}{L_2} + \dots + \frac{1}{L_n}$$

Simple example

Three coils: 1.8 mH, 2.9 mH and 4.7 mH connected in series.

$$L_{\text{eq}} = 1.8 + 2.9 + 4.7 = 9.4\ \text{mH}$$

If the same coils are connected in parallel

$$\frac{1}{L_{\text{eq}}} = \frac{1}{1.8} + \frac{1}{2.9} + \frac{1}{4.7} \approx 1.11315 $$

$$L_{\text{eq}} \approx 0.898\ \text{mH} $$

Compound example

Coils: 3.9 mH, 5.1 mH and 9.6 mH. The 3.9 and 5.1 mH coils are in parallel; that branch is in series with 9.6 mH.

Parallel branch

$$ L_{\parallel} = \frac{1}{\frac{1}{3.9}+\frac{1}{5.1}} \approx 2.210\ \text{mH}$$

Total series with 9.6 mH

$$ L_{\text{eq}} = 2.210 + 9.6 = 11.810\ \text{mH} $$

Units of inductance

Name	Symbol	Value in henries
Henry	H	1
Millihenry	mH	10⁻³ H
Microhenry	µH	10⁻⁶ H
NanoHenry	nH	10⁻⁹ H

Features

Build networks of unlimited complexity with nested series and parallel blocks.
Automatic calculation of equivalent inductance and branch current distribution.
Text and ASCII representations of the network for quick inspection.
Option to download calculation results as a plain text file.

In parallel the total inductance is always lower than the smallest branch value, which is useful for HF filter design. Series connection raises total inductance while current remains the same through each coil. For mixed networks consider parasitic series resistance and stray capacitance; these factors matter above a few hundred kilohertz. For precise models use measured coil data rather than nominal values.