Free printable: 12V Wire Gauge & Fuse Size Cheat Sheet
Two pages to tape inside a cabinet door or keep in the glovebox: wire gauge charts for 12 V at 3% and 10% drop and 24 V at 3%, a fuse-size table, and the largest fuse each wire size can take.
Download the PDF (2 pages, US Letter)
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How the numbers were made
Every cell is generated by the same code as the wire gauge and fuse calculators, and our automated tests check the PDF against that code. Basis: copper wire, ABYC voltage-drop method (CM = 10.75 × amps × round-trip feet ÷ allowed volts), ABYC 105 °C ampacity, outside the engine space, 1–3 conductors bundled, fuse at 125% of the load rounded up to the next standard size. For other conditions (engine space, bigger bundles, metric sizes, your exact length) use the calculators.
Preview: 12 V, 3% drop
| Amps | 5 ft | 10 ft | 15 ft | 20 ft | 25 ft | 30 ft |
|---|---|---|---|---|---|---|
| 5 A | 18 | 14 | 12 | 12 | 10 | 10 |
| 10 A | 14 | 12 | 10 | 8 | 8 | 6 |
| 15 A | 12 | 10 | 8 | 6 | 6 | 4 |
| 20 A | 12 | 8 | 6 | 6 | 4 | 4 |
| 25 A | 10 | 8 | 6 | 4 | 4 | 2 |
| 30 A | 10 | 6 | 4 | 4 | 2 | 2 |
| 40 A | 8 | 6 | 4 | 2 | 2 | 1 |
| 50 A | 8 | 4 | 2 | 2 | 1 | 1/0 |
| 60 A | 6 | 4 | 2 | 1 | 1/0 | 2/0 |
| 80 A | 6 | 2 | 1 | 1/0 | 2/0 | 3/0 |
| 100 A | 4 | 2 | 1/0 | 2/0 | 3/0 | 4/0 |
| 150 A | 2 | 1/0 | 3/0 | 4/0 | >4/0 | >4/0 |
| 200 A | 1/0 | 2/0 | 4/0 | >4/0 | >4/0 | >4/0 |
AWG, one-way length. ">4/0" = larger than 4/0: shorten the run, use parallel conductors per the manufacturer, or go to 24/48 V.