United States
Size your off-grid power system (US)
Tell us what you'll run — fridge, CPAP, laptop, lights — and we'll size your battery, solar and inverter from your real daily usage in watt-hours.
Takes about 5 minutes · Free · No experience needed
Built on NEC Article 551, Victron and Blue Sea guidance, with US pricing in USD — we'll always tell you when a job needs a licensed electrician.
What does this calculator do?
Roam Wired is a free off-grid power calculator for US van life, RVs and overlanding. You enter the appliances you plan to run — a 12V fridge, CPAP, laptop, lights, a water pump — and it adds up your real daily energy use in watt-hours, then sizes the battery, solar and inverter to match.
Whether you're building a dual-battery system into a van or choosing a portable power station, the numbers are the same: figure out your daily watt-hours first, then buy to fit. Once you know your target capacity, our US power station guides help you pick the right unit.