Wire Gauge Calculator: Cable

Size every cable, fuse and battery for a 12 V system — then hand over a wiring diagram and parts list as a PDF.

Cable turns wire-gauge guesswork into a complete DC plan. Add your loads, batteries, chargers and solar, and get correct cross-sections in AWG or mm², fuse ratings, voltage drop, runtime and charge time — plus a bill of materials you can actually shop.

WHAT YOU GET
- Cable sizing in AWG or metric: every result satisfies both your voltage drop budget and the current the cable has to carry
- A voltage drop budget per system — 3 %, 5 % or 10 %, the way ABYC separates critical from non-critical circuits
- Fuse ratings from standard sizes, never above what the recommended cable can carry
- Complete system model: loads, batteries, solar, chargers and alternator
- Runtime and charge-time results, checked against your own runtime and charge goals
- Duty cycle and daily on-time per load, so a fridge is not treated like a permanent load
- Sizes that keep themselves current: change a load, a length or your budget and every cable follows automatically
- Bill of materials, built automatically as you design
- Export a Full Report or bill of materials as PDF, or the wiring diagram as a PNG — preview everything before you share
- Works offline: every calculation runs on device, in the van, on the boat, in the workshop
- iPhone and iPad, in English, German, Spanish, French and Dutch

BUILT ON REAL ENGINEERING
Cross-sections come from standard AWG and mm² ladders instead of rounded guesses. Voltage drop is calculated over the whole run, there and back, for copper conductors. Current-carrying capacity follows the published ampacity tables for 105 °C conductors, and a fuse is never recommended above the capacity of the cable protecting it. Every number is visible, so you can check it before you cut a single cable.

WHO IT IS FOR
- Van and RV conversions
- Boats, marine installs and off-grid cabins
- Workshops, service technicians and installers who need a document to hand over
- Anyone who would rather calculate once than replace a melted cable

FROM IDEA TO INSTALLATION
1. Create a system, set its voltage and its voltage drop budget
2. Add loads from the component library
3. Add batteries, chargers, solar or an alternator
4. Read cable sizes, fuses, runtime, charge time and warnings
5. Export the report and buy the parts

One-time purchase — pay once, use forever. No account, no ads.

Get Cable today, add your first load, and know your cable size in under a minute. Build safer, build smarter.