VoltSizer - DC Wire Calculator

VoltSizer is a low-voltage DC cable sizing and electrical calculation app built for campervans, overland rigs, off-grid solar cabins, marine builds and mobile audio systems.

Unlike basic voltage drop calculators that only look up wire gauges, it treats your DC installation as a full engineering project, combining cable physics, real connection losses and coordinated overcurrent protection.

It performs full DC loop voltage drop calculations with chassis ground mode support, showing results at 20°C and elevated operating temperatures. Milliohm losses from crimp lugs, fuse holders, isolators and busbars are included so outputs match real multimeter readings.

The tool picks compliant fuse ratings following the 1.25× continuous current rule and derated wire ampacity. It flags low-voltage shutdown risks for inverters, pumps and electronics, and assesses motor inrush without overspecifying copper.

Organise multiple branch circuits with custom ambient temperature and bundling factors. Input equipment duty cycles to compute energy use and battery runtime, or simulate upgrades between 12 V, 24 V, 36 V and 48 V to find copper weight savings.

Practical workshop utilities: calculate safe limits for leftover cable spools, find maximum compliant run length for a fixed wire gauge, view pass/fail gauge matrices with failure explanations, and quickly reference terminal studs, lugs and torque specs.

Track commissioning checks including terminal torque and measured voltage drops. Auto-generate BOMs with cable lengths, copper weight and terminal counts, then export clean professional PDF specification sheets.

Fully offline with no internet required. No accounts, sign-ins or tracking — all your project data stays local on your device.、