Inductor Combination Calculator
Total inductance of any number of coils in series or parallel, with the other arrangement shown alongside.
Results
What this tool does
Inductors follow the same rules as resistors, which catches people out because capacitors — the other reactive component — follow the opposite ones. In series the inductances add; in parallel the reciprocals do, so the total always ends up smaller than the smallest coil. List as many values as you like, choose how they are wired, and this page gives the total along with what the other wiring would produce, so the comparison is right there.
Formula
in series: L = L₁ + L₂ + … · in parallel: 1/L = 1/L₁ + 1/L₂ + … (no coupling between coils)
Variables
| Symbol | Meaning | Unit |
|---|---|---|
values | The inductances, one per line or separated by commas | — |
arrangement | How they are connected | — |
L | Total inductance | mH |
LO | The other way round | mH |
LS | In series | mH |
LP | In parallel | mH |
TB | Number · value · share of the sum | — |
NC | Components | — |
MN | Smallest | mH |
MX | Largest | mH |
Worked example
- The inductances, one per line or separated by commas10, 22, 47
- How they are connectedseries
- Total inductance79.000000 mH
- The other way round5.997680 mH
- In series79.000000 mH
- In parallel5.997680 mH
- Number · value · share of the sum1 10 12.66 2 22 27.85 3 47 59.49
- Components3
- Smallest10.000000 mH
- Largest47.000000 mH
Limitations
- Electrical installations are governed by national wiring rules. Cable sizing also depends on installation method, grouping, ambient temperature and protection devices, which this calculator does not evaluate.
Frequently asked questions
Do inductors combine like resistors or like capacitors?
Like resistors. In series the inductances simply add; in parallel you add the reciprocals. Capacitors are the odd one out and do it the other way round, which is the single most common slip in this corner of electronics. A quick sanity check: putting two components in series should make the opposition to changing current larger, and inductance is exactly that opposition — so series must add.
Does this account for coils affecting each other?
No, and that is a real limitation rather than a rounding detail. Two coils close together share part of each other's magnetic field, and the mutual inductance between them adds to or subtracts from the total depending on which way round they are wound — the same pair can measure noticeably higher or lower simply by flipping one. The figures here assume the coils are far enough apart or shielded well enough that they ignore each other, which is what a circuit is normally laid out to achieve. If yours are wound on a shared core, they are a transformer and this is the wrong page.