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coil64

Calculates inductance for coils of almost any geometry

What it does

Computes inductance, and the dimensions to achieve a target inductance, for a long list of coil forms: single-layer air-cored solenoids, multilayer and sectioned windings, flat spirals, toroids on ferrite and powdered-iron cores, ferrite rods, pot cores, meander traces on a PCB, and coupled coils. It also does self-resonant frequency, Q, and the reverse calculation from a measured inductance back to a wire length.

Why you would want it

Winding an inductor is a place where the textbook formula and the bench disagree, because the formula assumes a geometry you did not build. Coil64 covers enough forms that the one in front of you is usually there, and it computes both directions -- how many turns for this inductance, and what did I just wind. For matching networks, traps and filters that saves an evening of trimming.

Before it will work

None beyond a desktop session. It calculates; it talks to no hardware.

How it installs

  • git (qmake) — https://github.com/radioacoustick/Coil64 at v2.4.39
  • build dependencies: build-essential, qtbase5-dev, qt5-qmake, qtbase5-dev-tools
  • the project's build system has no install rule; the binaries listed below are copied into the prefix instead
  • Built from this tag in a Debian 13 container on 2026-08-28: qmake exits 0, make exits 0, and a Coil64 executable appears in the source root. Resources are compiled in through Qt's resource system, so the binary is self-contained and copying it into a prefix is sufficient -- unlike MSHV, the catalog's other qmake unit, which reads data from directories beside itself.

Binaries this produces:

  • Coil64 → coil64

Known problems

Its accuracy is the accuracy of the empirical formulas behind it, which are good for the geometries they were derived for and degrade outside them -- a very short, very wide coil is where the classic solenoid formulas stop being trustworthy and the program does not warn you. Amidon and manufacturer core data is built in and ages as parts are discontinued. Measuring the finished coil with a NanoVNA remains the check.

Toolkit risk

  • qt5: unknown, checked 2026-08-28 — Builds against qtbase5-dev. Upstream has published no Qt6 plan that this check found; recorded as unknown rather than guessed.

Keeping it current

  • probe: github tags (radioacoustick/Coil64)
  • strategy: rebuild
  • Tagged releases, several a year. Latest is v2.4.39, and the default branch's head is b9b4e834ecb7 (read from the branch, not from GitHub's updated_at -- D-032).

Where to get help with the software itself

Valery Kustarev. GitHub issues at the URL above; the wiki there documents which formula each calculation uses, which is worth reading before trusting a result at the edge of a geometry.

Source: catalog/packages/coil64.yaml