Power Station Size Calculator
Pick the appliances you need to run and get a recommended power station capacity plus matching models.
The formula, every assumption, and the primary sources behind this tool are published on this page.
Results
Enter hours for the appliances you want to run, then compute.
How it works
Add up a day of the appliances you pick, then divide by the delivery fraction (usable capacity × inverter efficiency) to get the nameplate capacity a station needs, and snap up to a standard size. This matches the runtime calculator's loss model.
delivery_fraction = usable_fraction (0.85) × inverter_efficiency (0.85) = 0.7225required_capacity_wh = daily_wh / delivery_fractionrecommended = smallest standard tier where tier_wh ≥ required_capacity_wh tier_output_w ≥ running_w tier_surge_w ≥ peak_w
daily_wh- Energy your selected appliances use in a day, watt-hours.
delivery_fraction- Share of nameplate watt-hours actually delivered to AC loads — usable fraction (0.85) × inverter efficiency (0.85) ≈ 0.72.
required_capacity_wh- Nameplate capacity needed = daily_wh ÷ (usable fraction × inverter efficiency).
recommended- Smallest standard station size (500 / 1000 / 2000 / 3000 Wh) that clears the capacity requirement AND has the rated output and startup headroom to drive your load. Capacity alone is not an answer: a 1,500 W hair dryer for 12 minutes is only 300 Wh, but no 500 Wh station in the catalog delivers more than 500 W.
Assumptions
- A station delivers roughly 72% of its rated watt-hours to an AC load — about 15% held by the BMS reserve, then ~15% lost in the inverter — the same figures the runtime calculator uses.
- The recommendation covers one day of the selected loads on a single charge. For multi-day off-grid autonomy, use the solar battery bank calculator.
- The station must handle the running and peak watts shown, not just the capacity — so the recommended tier is held to both. Each tier's rated output and startup headroom come from the weakest catalog unit at that capacity, which is why a short high-wattage load can push the recommendation up a size even though its watt-hours are small. Suggestions below screen out models whose published surge rating is under the peak; models that publish only a boost mode are kept (surge unknown) and marked, so confirm their startup rating before buying.
- Sizes snap up to the nearest common tier that can both store and deliver what you need. A requirement above 3000 Wh — or a load no single tier can drive — points to multiple units or a home battery, not one portable station.
FAQ
What size power station do I need?
Add up the watt-hours your appliances use in a day, divide by about 0.72 (usable capacity × inverter efficiency), and pick the next standard size up — then check that size can actually deliver your running and startup watts, because a brief high-wattage load needs a bigger station than its watt-hours suggest. This tool applies both tests.
Should I size by capacity or by wattage?
Both. Capacity (Wh) sets how long it runs; rated output (W) sets what it can power at once. A big battery with a small inverter still can't start a 1500 W heater.
Can one power station run my whole house?
Rarely. Portable stations top out around 3–4 kWh and a few thousand watts. Whole-home backup needs a larger home battery — size that with the battery bank calculator.
Sources
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