The Outage HouseKeep the essentials running when the power goes out
Room: Living room

Power Station Calculator for a Power Outage

Guide type
Tool
Last reviewed
Sources
23 cited
Tested by us
No. How we research

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Short answer

You need two numbers. First, the watts of everything that may run at the same time: the station's continuous output must be higher. Second, the watt-hours you use in a day: the battery must be bigger. The calculator below does both, adds about 20 W the station uses on its own (our assumption, based on the two makers that publish it 1,2), and counts 85 % of the label capacity as usable 3,4. Example: a fridge-freezer (about 55 W on average 5) and a Wi-Fi router for 24 hours need a battery of about 2,300 Wh.

How to use the calculator

  1. Tick what you need during an outage. Keep it short: most people start with the fridge, heat, a medical device and internet.
  2. Correct the watts if your appliance’s label says otherwise. Our figures are the ones in the list below the calculator.
  3. Set the hours a day. A fridge counts 24 hours because its figure is already an average; a microwave may run 15 minutes.
  4. Read the results: the watts if everything runs at once, the energy per day, the battery you need for 24 hours, and how long three common sizes last.

Pick what you need to keep running

Tick each appliance, then adjust the watts from your own label and the hours you expect to use it each day.

Heating
Kitchen
Medical
Internet
Living room
Basement
Other
Usually too big
Your own appliance
Your outage plan
All running at once
0W
Energy per day
0Wh
Battery for 24 h
0Wh

Includes about 20 W the station uses on its own, all day (our assumption), and 85 % usable capacity.

Station sizeHow long your daily plan lasts
1,024 Wh–
2,048 Wh–
3,584 Wh–

    How long a 1 kWh or 2 kWh station lasts

    For a steady load, with our method (85 % usable, plus 20 W for the station):

    Steady load 1,024 Wh station 2,048 Wh station
    50 W (close to a CPAP’s typical draw) ≈ 12.4 h ≈ 25 h
    100 W (a 55-inch TV and a router) ≈ 7.3 h ≈ 15 h
    300 W ≈ 2.7 h ≈ 5.4 h
    1,000 W (a coffee maker) ≈ 51 min ≈ 1.7 h

    One trap: many stations switch off on their own under a small load. Turn energy-saving and auto-off modes off before an outage; our sump pump and furnace guides show how for several models.

    Running watts, startup watts and why they differ

    • Running watts decide the station’s continuous output. If everything you ticked may run at the same moment, the station must deliver at least the “all running at once” figure. For a fridge, the calculator uses its nameplate (725 W for a 16 cu ft model 7), not its 24-hour average.
    • Startup watts matter for motors and compressors. As a general rule, a motor draws about three times its running current for a moment as it starts 7. Makers’ own figures can be lower: a Liberty 1/3 HP sump pump is rated 5.2 A running and 8 A at start-up 8. Check the station’s surge rating against your appliance.
    • The label can mislead. A “1,200 W” microwave is its cooking power; the Panasonic NN-SN686S draws 1,480 W from the outlet 9. Use the input figure.

    Why our runtimes are lower than the label

    Three reasons, all built into the calculator. They overlap a little, which keeps the estimate on the safe side:

    • Not all of the battery is usable. OutdoorGearLab measured 910 Wh out of an advertised 1,070 Wh, about 85 % 3. Outdoor Life measured 76 to 92 % at a 380 W draw 4.
    • The station uses power on its own. BLUETTI publishes about 10 W for the Elite 200 V2 and 20 W for the Apex 300 1,2. Most makers publish nothing, so we assume 20 W, all day.
    • Small loads vary more. At a 34 W draw, Outdoor Life got 40 to 77 % 4. The calculator already charges 20 W of station use on top of a small load, which lands near the low end of that range; some stations do worse, most do better.

    When a portable station is not enough

    • Electric water heaters and clothes dryers: 4,500 to 5,500 W and up to 5,000 W 7. A few large stations offer 120/240 V, such as the BLUETTI Apex 300 with its voltage switch 2, but they empty fast at these loads.
    • Baseboard heaters: many are 240 V and wired to the panel; Ouellet sells its standard line in 240/208 V and 120 V versions 10.
    • Well pumps: Franklin sells its 4-inch well motors above 1/2 hp only at 230 V 11.
    • Electric heat in general: a 1,500 W space heater empties a 2 kWh station in about an hour.

    For these, see a whole-home battery or a generator connected by an electrician. Guides on heating, sump pumps and the fridge go further.

    Where our figures come from

    Every default wattage comes from a published source; the default hours and the 20 W the station uses on its own are our assumptions, which you can change:

    • Fridge-freezers, chest freezers and TVs: ENERGY STAR certified-product data 5,12,13. We use the median for fridges and TVs, and the highest certified model for 9 to 21.7 cu ft chest freezers. For a fridge’s running draw, we use the nameplate of a 16 cu ft frost-free model, 725 W 7.
    • Furnace blower: a field study of 31 furnaces 14.
    • Boiler pump, pellet stove, sump pump: Grundfos, Forge & Flame and Liberty Pumps documents 8,15,16.
    • CPAP and oxygen: ResMed user guides, Inogen and Philips 17,18,19,20. Use your own device’s figure, and ask your care provider.
    • Internet: Starlink and eero 21,22,23.
    • Everything else: the nameplate list of Virginia Cooperative Extension 7. Nameplate figures are maximums, so these runtimes err on the safe side.

    Our method is on the how we research page.

    Questions

    How long will a 1000W power station last?

    A 1000 in a name may mean its output in watts or, roughly, its capacity in watt-hours: check the Wh on the label. The Jackery Explorer 1000 v2 is rated 1,500 W output and 1,070 Wh 6; OutdoorGearLab measured 910 Wh from it 3. At a steady 100 W, plus about 20 W for the station itself, that is about 7.6 hours.

    What size power station do I need?

    Add the watt-hours of each appliance (watts × hours a day), add about 480 Wh for the station's own use over 24 hours, and divide by 0.85. Then check that its continuous output covers everything that may run at once, and that its surge rating covers motors as they start.

    How big a power station do I need for a fridge?

    The median ENERGY STAR full-size fridge-freezer uses 478 kWh a year 5, about 1.3 kWh a day. With the station's own use, that is about 2,100 Wh for 24 hours. Your fridge's EnergyGuide or EnerGuide label gives its own yearly figure.

    Can a portable power station run household appliances?

    Most 120 V appliances below its continuous output, yes, for a while. A space heater or hair dryer empties it fast. An electric water heater (4,500 to 5,500 W) or a clothes dryer (up to 5,000 W) 7 is beyond most portable stations; only a few large 120/240 V models come close, and 240 V appliances need a 240 V source.

    Bottom line

    Size a station on watt-hours first, then check its continuous output and its surge rating. For an outage, keep the list short: the fridge, the furnace blower or a medical device, internet and lights. Heating with electricity and 240 V appliances are a job for a bigger system.

    Related guides

    What we checked, and what we didn't

    Checked
    • Every appliance figure in its source: ENERGY STAR data, maker documents, a field study and a university extension list
    • The 85 % usable capacity in two published bench tests
    Not checked
    • Your own appliances: labels and real use vary. We have not tested any appliance or station.
    • Idle draw of most stations: not published, so we assume 20 W.
    • Startup watts of each appliance: few makers publish them.
    • Air fryers, induction plates, treadmills, slow cookers and aquariums: not yet sourced; use the Your own appliance line.

    Sources

    1. BLUETTI Elite 200 V2 user manual · BLUETTI
    2. BLUETTI Apex 300 user manual (US) · BLUETTI
    3. Jackery Explorer 1000 v2 review: measured 910 Wh of 1,070 Wh (July 23, 2026) · OutdoorGearLab
    4. The Best Portable Power Stations, Tested and Reviewed: output at 34 W and 380 W loads (updated May 5, 2025) · Outdoor Life
    5. ENERGY STAR Certified Residential Refrigerators dataset (queried 2026-11-10; median computed by us) · U.S. EPA ENERGY STAR
    6. Jackery Explorer 1000 v2 user manual (specifications) · Jackery
    7. Energy Series: Estimating Appliance and Home Electronic Energy Use (BSE-301), nameplate wattage list · Virginia Cooperative Extension
    8. 250-Series sump pump specifications (rev. 1/24/2012): 1/3 HP, 115 V, 5.2 A full load, 8 A locked rotor · Liberty Pumps (distributor-hosted copy)
    9. NN-SN686SAZH microwave: features and specifications · Panasonic
    10. OFM standard baseboard heater product sheet · Ouellet
    11. 4-inch encapsulated submersible motor (order tables: 115 VAC and 230 VAC models) · Franklin Electric
    12. ENERGY STAR Certified Residential Freezers dataset (queried 2026-11-10; range computed by us) · U.S. EPA ENERGY STAR
    13. ENERGY STAR Certified Televisions dataset (queried 2026-11-10; median computed by us) · U.S. EPA ENERGY STAR
    14. Electricity Savings from Variable-Speed Furnaces in Cold Climates (field monitoring of 31 furnaces), 2004 · Pigg and Talerico, ACEEE Summer Study proceedings
    15. Grundfos UPS 15-58 FC circulator pump (59896341) specification sheet · Grundfos (distributor-hosted copy)
    16. Winter storm outage? No problem (Harman approved battery backups) · Forge & Flame (Hearth & Home Technologies)
    17. AirSense 11 user guide, technical specifications (copy hosted by NIH StrokeNet) · ResMed
    18. AirSense 10 user guide (copy hosted by NIH StrokeNet) · ResMed
    19. Energy savings calculator (Inogen At Home) · Inogen
    20. EverFlo home oxygen system: specifications (350 W average) · Philips Respironics
    21. Starlink Standard specification sheet · Starlink
    22. How can I power my Starlink Mini? (help center) · Starlink
    23. How much power does eero use? · eero (Amazon)

    Revision history

    2026-11-10First version.