Electric Motor Winding Calculator
Pick a pole-count range and a slot-count range, and the calculator finds every feasible three-phase winding combination in that range, scores each one by winding factor, and lets you inspect the coil-by-coil layout for any combination you select. It covers both integer-slot and fractional-slot windings, single- and double-layer.
Motor datasheets rarely explain why a design uses, say, 12 slots and 8 poles instead of 9 and 6 — both are common, valid three-phase windings, but they trade off winding factor (how efficiently the coils convert current into torque), cogging behaviour, and manufacturability differently. This calculator lets you compare combinations side by side before committing to one. For background on the terms used here, see the electric motor glossary.
Turncircles builds stators on PCB/DCB (printed/direct copper bond) boards, which can only realize concentrated-slot windings (slots per pole per phase q < 1) — the coils are wound around individual teeth as traces or bonded copper, with no overlap between phases. Integer-slot and fractional-slot windings, which need overlapping distributed coils, are not manufacturable with this technology. They're included in the matrix below for reference and comparison, but concentrated-slot is the only type Turncircles can build, which is why it's selected by default. Concentrated-slot and integer-slot windings can each be built as single- or double-layer; fractional-slot windings (q > 1) can only be double-layer.
Determine Number of Slots and Number of Poles
Set a pole range and a slot range, then narrow the matrix by winding type and layer count. Click any colored cell to load that combination below.
Slots/Poles
Investigate and Edit the Selected Winding Layout
Select a combination in the matrix above to see its coil layout here, including coil span, pole pitch, periodicity and winding factor. Toggle between single- and double-layer where both are available.
Winding Diagram
Harmonic Spectrum
The fundamental (n=1) is what drives torque; higher harmonics are unwanted byproducts of the coil layout. The winding-factor chart shows how strongly this winding couples to each harmonic order; the MMF chart shows the resultant spectrum after the three phases combine, where every third harmonic (3, 9, 15, ...) cancels out in a balanced winding.
This calculator is provided for design exploration and does not replace detailed electromagnetic simulation. Turncircles makes no warranty as to the accuracy of results; see our Terms of Use.
How the Calculator Works
Slots per pole per phase (q): for Q slots, 2p poles and m=3 phases, q = Q / (2p·m). A whole-number q gives an integer-slot winding (coil groups of equal size per pole); q below 1 gives a concentrated-slot winding (short-pitch, non-overlapping coils, the type Turncircles' PCB/DCB stators build); q above 1 and non-integer gives a fractional-slot winding.
Winding factor (kw1): how effectively the physical coil layout couples to the fundamental rotating field, found from the phasor sum of each phase's slot EMFs (the "star of slots" method). A winding factor near 1.0 wastes less copper per unit of torque; most practical designs fall between about 0.85 and 0.96.
Periodicity (t): the greatest common divisor of slot count and pole-pair count. A higher t means the winding pattern repeats more times around the machine, which can simplify manufacturing but does not by itself change the winding factor.