Power station runtime calculator
How many hours for your fridge, router or CPAP? Tick your devices and choose how many days. We tell you what size battery you need, and which stations can do it.
- You need a battery of
- –
- Per day
- –
- All on at once
- –
How we work it out: battery Wh × 0.85 ÷ (device watts + 10 W)
These stations can do it
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In short: hours = battery Wh × 0.85 ÷ (device watts + 10 W for the station itself). A 1,000 Wh station runs a 10 W router for about 42 hours, and an average 45 W fridge for about 15 hours.
- LED lamp 8 W 47 h
- Internet router 10 W 43 h
- CPAP machine 12 W 39 h
- Fridge 45 W 15 h
- Laptop 60 W 12 h
- LED TV 80 W 9.4 h
- Microwave 1200 W 42 min
- Electric kettle 2000 W 25 min
How we count: 1,000 Wh × 0.85 ÷ (device watts + 10 W). These are average watts. Your device may use more or less.
How to read the result
- Per day (Wh): each device’s watts times the hours it is on. This is what empties the battery.
- All on at once (W): the power the station must give with everything on together. If this is more than the station’s max power, it shuts off.
- Battery you need: Wh per day × days ÷ 0.85.
Three mistakes to avoid
Forgetting the fridge needs a push to start
For a split second when they start, fridges and freezers need several times their usual power. A 300 W station may have enough battery for the day and still fail to start the fridge. The calculator leaves those stations out.
Counting on anything that heats
Kettles, space heaters, hair dryers and hot plates use 1,200 to 1,800 W. A 1,000 Wh station runs them for minutes, not hours.
Leaving the outlets on for nothing
When its outlets are on, the station uses a few watts even if nothing is plugged in. Turn them off when you don’t need them, and charge phones and laptops over USB-C.
YesThe device plugs into the station
NeverSending the station’s power into a wall outlet or your home’s wiring
Power would flow back into the power lines. That is dangerous for you and for the people fixing them.
How long should you plan for?
FEMA’s Ready.gov asks you to keep supplies for several days after a disaster. With a fridge running, one station alone rarely lasts 3 days. A solar panel makes the difference.
Questions
How long will a 1,000 Wh power station run a refrigerator?
About 13 to 15 hours. A recent fridge uses about 1 to 1.5 kWh per day, or 45 to 60 W on average, and the station itself uses about 10 W while its outlets are on. The math: 1,000 Wh × 0.85 ÷ (55 W + 10 W) ≈ 13 hours. To find your fridge’s number, look at the yearly kWh on its EnergyGuide label and divide by 365.
Why multiply by 0.85 and add 10 W?
Some energy is lost when the battery turns into power for your outlets, so we only count 85% of the battery the brand gives. And the station itself uses about 10 W while its outlets are on (BLUETTI states about 15 W for one of its models), so we add it to your devices. It is a careful estimate.
How long will a power station run a CPAP?
Without the heated humidifier, a common CPAP uses about 10 to 15 W (ResMed measures about 7 Wh per hour for the AirSense 10 alone). So an 8-hour night needs about 100 Wh, plus about 80 Wh for the station itself. With the humidifier and heated tube, count 25 to 45 W: two to four times more. Ask your equipment supplier for the exact number, and always have a backup plan.