What size power station do I need?
Set what you'll run and for how long. You get the battery size, output and surge, and which models can do it.
Start from
What stays on
980 W running- Refrigeratorsurge 24 h
- Freezer, chestsurge 24 h
- LED bulb
- Internet router and modem
How long is the outage
Advanced
| Appliance | Running W | Start-up W | Use per day | Wh in 1 day |
|---|---|---|---|---|
| Refrigerator | 400 | +1,200 | all day | 1,400 |
| Freezer, chest | 500 | +1,000 | all day | 600 |
| LED bulb × 4 | 60 | – | 6 h | 360 |
| Internet router and modem | 20 | – | 24 h | 480 |
| Total | 980 | +1,200 | 2,840 |
- Starting
980 running + 1,200 largest start-up = 2,180 W - Running
980 × 1.20 headroom = 1,176 W, rounded up to 1,200 W - Battery
2,840 Wh ÷ 85% inverter × 1.20 headroom = 4,009 Wh
Headroom 20% · inverter efficiency 85% · fuel gas. Change these under Advanced.
You need about
4,010Wh
980 W output · 2,180 W surge
Best fit
Portable generator
A battery would need about 4,010 Wh. A generator covers this on fuel you can store.
- Portable generator
- 1,200 W run · 2,200 W start
- Power station
- 4,010 Wh · 980 W out
- Standby generator
- 10 kW
Refrigerator uses 49% of the battery energy. It's what makes a battery expensive.
See 1 model that fitRun a generator outdoors only, 20 ft or more from windows, doors and vents. Never in a garage. CDC
The short answer
Multiply each appliance's watts by the hours you'll use it. Add them up, divide by 85% for inverter losses, and add 20% headroom. A fridge for one day comes to about 1,980 Wh. The power station's output must also cover everything running at once, and its surge must start the biggest motor.
Models that meet your numbers
Checked against each manufacturer's published specs on October 11, 2026. Links go to the manufacturer. If we add affiliate links, we may earn a commission. That never changes which models pass. Disclosure
| Model | Rating | Your numbers | Runtime or fuel | List price | Link |
|---|---|---|---|---|---|
| EcoFlowDELTA Pro 3Power station | 4,096 Wh · 4,000 W | Capacity Output SurgeMeets your needs | 29.4 h at your load | — | Specs |
How long each model runs a fridge
| Model | Capacity | Runs a fridge for |
|---|---|---|
| EcoFlow DELTA 3 Plus | 1,024 Wh | 15 h |
| Anker SOLIX C1000 | 1,056 Wh | 15 h |
| Jackery Explorer 1000 v2 | 1,070 Wh | 16 h |
| BLUETTI AC180 | 1,152 Wh | 17 h |
| EcoFlow DELTA 2 Max | 2,048 Wh | 30 h |
| BLUETTI Elite 200 V2 | 2,074 Wh | 30 h |
| Anker SOLIX F3800 | 3,840 Wh | 56 h |
| EcoFlow DELTA Pro 3 | 4,096 Wh | 60 h |
Full-size fridge at 1,400 Wh a day (ENERGY STAR median), 85% inverter efficiency, nothing else plugged in.
How we calculate
Energy for the outage
Watts × hours of use for each appliance. Fridges and freezers use measured daily energy from ENERGY STAR data, because they cycle on and off.
energy = Σ watts × hours × quantityAllow for losses
Turning battery power into household AC wastes some as heat.
capacity = energy ÷ 0.85Leave headroom
20% more covers cold weather, battery aging and what you forgot.
size = capacity × 1.2
Output must cover the running total. Surge must cover the running total plus the largest start-up. Full method
Questions
How long will a power station run a refrigerator?
A typical full-size fridge uses about 1,400 Wh a day, or 58 W on average as it cycles. A 1,000 Wh power station gives about 15 hours at 85% inverter efficiency. The table above has the figure for each model.
What size power station do I need for a fridge for 24 hours?
About 1,980 Wh: 1,400 Wh of energy, divided by 85% efficiency, plus 20% headroom. It also needs at least 1,600 W of surge to start the compressor.
How big a power station do I need for a CPAP?
A CPAP with a heated humidifier draws up to 120 W, so 8 hours is 960 Wh. With efficiency and headroom, that's about 1,360 Wh. Without the humidifier it's about half that. Check your device's label.
Can a power station run a sump pump?
Only if it can handle the start-up surge. A 1/2 HP sump pump needs up to 3,200 W for a moment. Of the models we list, EcoFlow DELTA 3 Plus, EcoFlow DELTA 2 Max, Anker SOLIX F3800, EcoFlow DELTA Pro 3 have enough surge rating.
What is the difference between Wh and W?
Watt-hours (Wh) is how much energy the battery holds, like the size of a fuel tank. Watts (W) is how much it can deliver at once. You need enough of both: Wh for how long, W for what runs at the same time.
Why don't I get the full rated capacity?
Converting battery power to household AC loses some energy as heat. We assume 85% efficiency, which you can change under Advanced. Cold weather and an aging battery also reduce what you get.
Sources
- ENERGY STAR certified refrigerators and freezers, median annual energy use
- U.S. Department of Energy, Estimating Appliance Energy Use
- Champion Power Equipment, Generator Wattage Chart, running and starting watts
- Model specs: each manufacturer's product page, linked in the table above