What Size Portable Power Station Do I Need?

Sizing is the step most buyers skip, and it is the reason so many power stations end up either useless or oversized. The arithmetic is simple: one sum for what it must start, one for how long it must last.

This is a research-based explainer using manufacturer-published ratings. No prices or marketplace data appear here.

Step 1: list what runs at the same time

Write down every device you want powered simultaneously and its wattage — usually printed on the appliance or its label. Add them up. That total is your minimum continuous inverter rating.

Add headroom of about 20%. An inverter running permanently at its ceiling is an inverter that gets hot and shuts down.

Step 2: check the biggest start-up surge

Anything with a motor or compressor — fridges, pumps, power tools — draws several times its running wattage for a moment at start-up. Your unit's surge rating must cover the largest of those spikes.

This is why a fridge that runs at 150W can still trip a small inverter. Size for the spike, not the average.

Step 3: convert to watt-hours

Multiply your average draw by the hours of runtime you need. A 100W average over 10 hours is 1000Wh, so you want a 1kWh unit at minimum, and more once you allow for conversion losses.

For a fridge, use its daily energy consumption from the energy label rather than its nameplate wattage — the compressor cycles rather than running constantly.

Step 4: pick the capacity band

Under 500Wh: phones, laptops, cameras, lights, a router, most CPAP machines. Compact and genuinely carryable.

700Wh–1.2kWh: the mainstream band. A camp fridge for a weekend, or a household fridge plus electronics for several hours in an outage.

2kWh and up: outage backup with real endurance, and higher-wattage appliances. Around 50 lb, so plan placement. Above that, 4kWh with 240V output covers well pumps and circuit-level backup.

Step 5: decide whether solar changes the answer

Solar input is capacity you did not have to buy. A modest array can carry a share of daytime load and stretch a mid-size unit across several days.

It does not replace inverter capacity. If the appliance will not start, no amount of solar helps.

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