Wire your rig right, then check it all fits

Wire Your Rig has free calculators for building out a camper van, truck camper or overland rig: wire gauge, fuses, batteries, solar and DC-DC charging, inverters, and a payload check for everything you add. Every result shows the formula behind it. Runs in your browser: no sign-up, no cookies, no tracking.

Free printable: 12V Wire Gauge & Fuse Size Cheat Sheet (PDF, 2 pages, no email needed).

• Wire gauge & voltage drop calculator
  Find the right copper wire size for a 12, 24 or 48 V DC circuit from current and run length, using the ABYC 3%/10% voltage-drop method plus ampacity and fuse checks. AWG and mm².
• DC fuse size calculator
  Size a fuse or breaker for a 12V/24V DC circuit: 125% of continuous current, rounded to the next standard rating, then checked against the wire's ampacity.
• Battery bank size calculator (LiFePO4 vs AGM)
  Build a daily load budget for your camper or overland rig and size a LiFePO4 or AGM battery bank by days of autonomy, margin and depth of discharge.
• Solar & DC-DC charging calculator
  Will your solar panels and DC-DC (alternator) charger keep up with your daily amp-hours? Estimate daily charge, net balance, days until empty, and solar watts needed.
• Inverter size calculator (with surge)
  Size an inverter for a camper or van: continuous watts with headroom, start-up surge, DC battery current and the fuse for the inverter cable.

Build-out check

• Rig build-out payload & GVWR calculator
  Building out your rig? Check how much payload is left after the batteries, drawers, rack, rooftop tent, water, people, gear and trailer tongue weight, using your door-jamb placard or a scale ticket and GVWR.

How to use them together

1. List your devices in the battery calculator to get daily amp-hours and a bank size.
2. Check that solar and DC-DC charging keep up.
3. If you run AC devices, size the inverter.
4. Size every cable with the wire gauge tool and every fuse with the fuse tool.
5. Before you bolt it all in, check the battery bank, drawers, rack, tent and everything else fit your payload.