What size power do you really need?

Free, brand-neutral calculators for power stations, generators, RV solar and home backup. Enter your devices, get the exact size, and see models that actually fit.

Why use these calculators?

Manufacturer calculators only recommend their own products and often skip start-up surge, inverter losses and cold-weather derating. Ours apply the same formulas to every brand. You'll see the math behind every result, so you don't overpay for capacity you won't use or end up with a unit that trips when your fridge starts.

  • Real-world numbers: 85% inverter efficiency, duty-cycle-aware fridge consumption, 75% solar derating.
  • Start-up surge checks for pumps, fridges and AC units.
  • Sun hours for every US state for solar sizing.
  • Shareable results: every result has its own link.

Runtime guides by device