Calculate guitar pickup coil wire length and DC resistance for any turns count, AWG, and bobbin dimensions.
Enter the number of coil turns (the form opens at 8,000), choose a magnet-wire gauge between AWG 40 and AWG 44, and supply the inner and outer diameters of the bobbin in millimeters — the defaults are 6.35 mm and 35 mm.
Wire length assumes each turn sits at the mean of the two diameters: length = turns × π × (inner + outer) ÷ 2. DC resistance then follows from copper resistivity, 1.724 × 10⁻⁸ Ω·m, multiplied by that length and divided by the cross-sectional area of the selected gauge.
With the default inputs the model winds about 519.6 m of AWG 42 wire for roughly 2.84 kΩ. Rewinding the identical coil in AWG 44 reads about 4.54 kΩ, because the thinner conductor carries close to 1.6 times the resistance per meter of length.
It multiplies the turn count by the circumference at the mean bobbin diameter: turns × π × (inner + outer) ÷ 2. With the default 8,000 turns on a 6.35 mm / 35 mm bobbin, the mean diameter is 20.675 mm and the wire length works out to about 519.6 m.
Resistance equals copper resistivity (1.724 × 10⁻⁸ Ω·m) times the wire length, divided by the conductor's cross-sectional area for the chosen AWG. The default coil computes to roughly 2,842 Ω, displayed as both ohms and kilo-ohms.
A finer gauge has a smaller cross-section, so the same length of wire resists more. AWG 44 (0.05012 mm conductor) carries about 1.6 times the resistance of AWG 42 (0.06334 mm); the identical 8,000-turn coil reads near 4.54 kΩ instead of 2.84 kΩ.
In this model, yes — every extra turn adds one mean-circumference of wire to the coil. Going from 8,000 to 10,000 turns of AWG 42 on the default bobbin stretches the wire from 519.6 m to 649.5 m and lifts the resistance from 2.84 kΩ to 3.55 kΩ.
AWG 40 through AWG 44, with bare-conductor diameters from 0.07938 mm down to 0.05012 mm taken from the built-in wire table. The model places every turn at the mean diameter and does not account for insulation build-up, winding tension, or temperature.