What Size Portable Power Station Do You Actually Need?

Runtime in hours equals usable watt-hours divided by the load in watts. The catch is the word usable: an inverter converting DC battery power to household AC loses energy as heat, so plan on getting about 85% of the number printed on the box.

A 1,024Wh station therefore delivers roughly 870Wh in practice. Running a 45W CPAP machine, that is about nineteen hours — two full nights. Running a 1,200W electric kettle, it is about forty minutes of continuous boiling, which in practice is a week of morning coffee because the kettle only runs for three minutes at a time.

That second example is the point most sizing guides miss. What matters is not a device's wattage but its wattage multiplied by the time it actually spends switched on. A microwave rated at 1,500W is a trivial load if you use it for four minutes a day and a catastrophic one if you are trying to cook dinner.

• Usable capacity ≈ rated watt-hours × 0.85
• Runtime (hours) = usable watt-hours ÷ device watts
• Daily need (watt-hours) = device watts × hours actually running per day

These are typical running figures for equipment people commonly want to power. Check the label on your own device where it matters — figures vary meaningfully by model, and older appliances are usually worse.

• Phone: 15–25Wh for a full charge (so a 1,000Wh unit is roughly 40 charges)
• Laptop: 45–90W while working
• Wi-Fi router and modem: 10–20W
• Starlink standard dish: 50–75W
• LED lights: 5–10W each
• CPAP without humidifier: 30–60W · with heated humidifier: 80–110W
• Full-size refrigerator: 100–200W while the compressor runs, about 1–2kWh per 24 hours in total
• TV: 60–120W
• Coffee maker: 800–1,200W
• Electric kettle: 1,200–1,500W
• Microwave: 1,200–1,700W drawn (the advertised number is cooking output, not draw)
• Space heater: 750–1,500W
• Circular saw: 1,400–1,800W, with a much higher startup spike

Motors and compressors do not draw their running wattage at the moment they switch on. A refrigerator that hums along at 150W can demand 600W to 1,200W for a fraction of a second as the compressor starts. Well pumps and power tools are worse still.

If that spike exceeds the inverter's surge rating, the station shuts off to protect itself. You will see this as a unit that runs the fridge fine on the bench and then trips repeatedly overnight — the compressor cycles roughly every twenty minutes, so a marginal inverter gets many chances to fail.

This is why an 1,800W continuous rating with 2,400W of surge headroom is the practical floor for appliance backup, and why the inverter spec deserves as much attention as the battery spec. Some units also offer a boost mode that runs high-wattage resistive loads — kettles, heaters, toasters — above the nominal inverter rating. That trick works because resistive loads tolerate a reduced voltage; it does not help with motors.

Sizing gets much easier once you decide which of these you are actually buying for. Most disappointment comes from buying for one and expecting another.

Under 300Wh, USB-first. Phones, laptops, cameras, headlamps, a tablet on a flight. Units in this class often drop the AC inverter entirely, which sounds like a compromise and increasingly is not — if everything you carry charges over USB-C, the weight saved is worth more than an outlet you would not use. The Anker SOLIX C300 is the clearest example: 288Wh, about six pounds, 140W USB-C, and no AC outlet at all. Be honest about that limitation before you buy, because it also rules out anything with a wall-wart power brick.

500–1,000Wh, weekend and work. Camping trips of two or three nights, CPAP for a couple of nights, running a laptop and a Starlink dish from a truck. Here you want a real inverter but not a large one.

1,000–2,000Wh, the sweet spot. This is where most buyers should land: enough capacity for a weekend or a short outage, enough inverter to run essentially any household appliance, and still light enough for one person to carry. The Anker SOLIX C1000 Gen 2 sits squarely here at 1,024Wh and 1,800W continuous, with a full recharge in under an hour — which quietly solves the most common real-world failure, forgetting to charge it. The EcoFlow DELTA 2 offers the same capacity and inverter with the option to chain on extra batteries to 3,040Wh later, which is the right call if you are unsure how your needs will grow.

2,000Wh and up, genuine blackout insurance. Once you need a refrigerator to survive a night, you are budgeting in kilowatt-hours per day rather than hours of runtime. A fridge at roughly 1–2kWh per 24 hours plus lights, phones, a router and a CPAP is comfortably more than a 1kWh unit can carry. The Jackery Explorer 2000 v2 at 2,042Wh and 2,200W is built for exactly this, and 2kWh is the point where a power station stops being a convenience and starts being infrastructure.

Capacity is only half of an outage plan. A power station that takes eight hours to refill from the wall is a very different product from one that refills in fifty minutes, because in a rolling outage you may only get short windows of grid power.

Solar is the other path, and it is routinely oversold. A 400W panel array in good, direct, correctly angled sun realistically produces somewhere around 300W. Refilling a 1kWh station therefore takes roughly three and a half hours of genuinely good sun — and considerably longer on an overcast day, in winter, or with panels flat on the ground rather than aimed. Size panels for the weather you actually get, not the number on the panel.

Nearly every station worth buying now uses lithium iron phosphate (LiFePO4) cells rather than the older lithium-ion NMC chemistry. The relevant difference is lifespan: LiFePO4 is typically rated for 3,000 or more charge cycles to 80% of original capacity, against several hundred for NMC.

This matters for sizing because a slightly larger unit that you cycle shallowly will outlast a smaller one you drain to empty every trip. If the two candidates are close on price, the larger capacity is usually also the longer-lived purchase. LiFePO4 is also markedly more tolerant of heat, which is worth something if the unit lives in a vehicle.