What Size Power Station Do I Need? Capacity vs Output Explained (2026)
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Every power station is described by two numbers, and confusing them is the #1 sizing mistake. Here’s the 2-minute method that gets it right.
The two numbers
Capacity (Wh) — how much energy the battery holds. Decides how long things run. A 2000Wh station holds twice the energy of a 1000Wh one.
Output (W) — how much power the inverter delivers at once. Decides what can run. A 2400W inverter runs a microwave; a 1000W inverter trips trying.
You need enough of both. A 4kWh station with a 1000W inverter can’t run a 1500W kettle. A 1kWh station with a 2400W inverter (DELTA 3 Plus) runs the kettle — briefly.
fridge 150W × 10h ≈ 1500Wh
microwave needs 1000W+ sustained
neither wasted
Our RV sizer does this math for you — see the tools page.
The 2-minute method
- List your devices with their watts (check the label or our RV sizer’s device list).
- Multiply watts × hours per day for each, and add them up. That’s your Wh/day.
- Add 20% headroom. That’s your target capacity.
- Find your biggest single load (or two simultaneous loads). Your output watts must exceed it.
Example — home office backup: laptop 65W × 8h = 520Wh, monitor 30W × 8h = 240Wh, modem/router 20W × 8h = 160Wh, phones 60Wh. Total ≈ 980Wh → +20% ≈ 1,200Wh target. Biggest load: 65W. Any 1kWh station works — the Anker C1000 is plenty.
The common traps
- Forgetting surge: fridge compressors and pumps draw 2–3x their rated watts for a second at startup. Check the station’s surge rating, not just continuous.
- Sizing for the average, not the peak: your average load might be 300W, but the microwave’s 1000W is what trips the inverter.
- Ignoring recharge: a perfectly sized battery that’s empty on day two of an outage is a brick. Size the solar (or the wall-recharge plan) too — see our solar pairing guide.
Quick reference
| Daily need | Station size | Example pick |
|---|---|---|
| Phones, lights, laptop (~500Wh) | 500Wh–1kWh | Anker C1000 |
| + 12V fridge (~1,500Wh) | 1–2kWh | DELTA 3 Plus |
| + cooking/Starlink (~3,000Wh) | 2–3kWh | C2000 Gen 2 |
| Fridge + freezer 24h (~3,200Wh) | 3kWh+ | Anker F3000 |
| Multi-day home backup | 4kWh + solar | DELTA Pro 3 |
Sizing for specific appliances
The table above is a starting point — here’s the appliance-level math for the loads people actually ask about (using the 0.85 efficiency factor):
| Appliance | Typical draw | 1kWh station | 2kWh station | 4kWh station |
|---|---|---|---|---|
| Full-size fridge | ~150W avg | ~6h | ~11h | ~23h |
| Chest freezer | ~100W avg | ~8.5h | ~17h | ~34h |
| CPAP (no humidifier) | ~40W × 8h | 2–3 nights | 5+ nights | 10+ nights |
| Laptop + monitor | ~95W × 8h | ~1 workday | ~2 workdays | ~4 workdays |
| Portable AC (8k BTU) | ~1000W | ~50 min | ~1.7h | ~3.4h |
| Microwave | 1000W × 15min | ~4 meals | ~8 meals | ~16 meals |
Two deep dives: what size power station runs a refrigerator does the full fridge math including compressor surge, and home backup scenarios walks through 4-hour, 24-hour and multi-day outages hour by hour.