What this answers: “How long will a power station run my fridge, router and CPAP in an outage?” Tick the loads you’d plug in, replace the example watts with your own, and pick a station. The calculator uses the runtime formula BLUETTI publishes: capacity × usable % × inverter efficiency ÷ (load + self-consumption). It also checks whether the inverter can run everything you ticked at the same time.
Outage runtime calculator
Every value is editable. Nothing is stored or sent anywhere.
Loads (example watts — use your labels)
Average load = sum of (watts × hours per day) ÷ 24. Runtime = capacity × usable % × inverter efficiency ÷ (average load + self-consumption). Educational estimate only, not a guarantee.
How to get real watt numbers
The U.S. Department of Energy’s Energy Saver guidance says an appliance’s wattage is usually stamped on its nameplate, and that figure is its maximum draw. If only amps are listed, multiply by the voltage (120 V for most U.S. plug-in appliances). For a refrigerator, which cycles on and off, DOE suggests dividing the time it’s plugged in by three to estimate how long it actually runs. That’s why the example uses 8 hours a day. A plug-in watt meter over a full day gives you a better number than either estimate.
For runtime, energy matters more than the peak: a 150 W fridge running 8 hours uses 1,200 Wh a day. For the inverter check, peak watts are what count. The calculator adds up every ticked load as if all were on at once, a deliberately cautious test.
Three things that shorten real runtime
- Compressor and motor start-up surge. BLUETTI notes that its runtime formula is not suitable for inductive loads with compressors, such as refrigerators and air conditioners. Their start-up draw is well above the running watts, so treat fridge runtime as an estimate. Leave headroom on the inverter, and check the station’s surge rating against the fridge’s start-up draw.
- Heat-making loads. A 1,500 W space heater empties a 1,152 Wh station in about 35 minutes: 1,152 × 90% × 85% ÷ (1,500 + 15) W. Tick it in the calculator to see. Keep a portable station for electronics, the fridge and medical devices, and heat with something designed for it.
- Cold. Many LiFePO4 stations won’t recharge below freezing: BLUETTI lists the AC180’s charging range as 32–104 °F, and discharging as -4–104 °F. Keep the station indoors in a winter outage.
Furnace blowers are usually hardwired. Most furnaces can’t simply plug into a power station. Connecting one safely usually means an electrician-installed inlet or transfer switch, and never a “backfeed” cord into an outlet. Check your furnace’s nameplate and manual, and talk to a licensed electrician. Our panel capacity guide and portable vs. home battery guide cover when you’ve outgrown a plug-in station.
Stations in the calculator
The presets use specs from each maker’s product page, checked November 10, 2026. No prices are listed. Size from your own load total, then compare current prices yourself. For a broader comparison, including UPS switchover and expansion batteries, see the portable power station guide. To see how many emergency miles the same box could add to an EV, use the power station EV miles calculator.
BLUETTI AC180
1,152 Wh LiFePO4, 1,800 W AC output. BLUETTI publishes the 90% / 85% / ~15 W runtime figures this calculator uses by default.
BLUETTI AC200L
2,048 Wh LiFePO4, 2,400 W AC output, expandable with add-on batteries per BLUETTI.
See the AC200L at BLUETTI (sold out Nov 10)
BLUETTI showed the AC200L as sold out on Nov 10, 2026. Closest in-stock BLUETTI: Elite 200 V2 (2,073.6 Wh, 2,600 W) at BLUETTI.
ALLPOWERS R1500
1,152 Wh LiFePO4, 1,800 W pure sine wave inverter (3,000 W peak), per ALLPOWERS’ listing.
ALLPOWERS R2500 Plus
2,016 Wh, 2,500 W pure sine wave inverter (4,000 W peak), per ALLPOWERS’ listing. It can be expanded with ALLPOWERS’ B1000 battery.
See the R2500 Plus at ALLPOWERS (sold out Nov 10)
ALLPOWERS showed the R2500 Plus as sold out on Nov 10, 2026. Closest in-stock ALLPOWERS: R2500 V2 (1,920 Wh, 2,500 W) at ALLPOWERS.
Frequently asked questions
How long will a 1,000 Wh power station run a refrigerator?
It depends on the fridge. Using the calculator’s example (150 W, running 8 of 24 hours, 50 W average) and BLUETTI’s 90% / 85% / 15 W figures, a 1,000 Wh station lasts about 12 hours. Put in your fridge’s nameplate watts, or better, a watt-meter reading. Remember that compressor surge makes any fridge estimate approximate.
Can a power station run a CPAP all night?
Usually, if you size for it. A CPAP’s power supply label gives its maximum draw. Heated humidifiers and heated tubing add a lot, so check whether your figure includes them. Enter your machine’s watts and 8 hours, and leave margin.
Should I count every load at once for the inverter?
The calculator does, as a conservative check. In practice, a fridge, router and CPAP rarely all hit peak together. Start-up surge is the bigger risk, so keep headroom between your total and the station’s continuous rating.