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Power Station Runtime Calculator

Enter your power station's capacity and the devices you'll plug in during an outage. The calculator accounts for inverter losses and shows how many hours the station will last and what drains it fastest.

Wh
Printed on the case: 512, 1024, 2048 Wh and so on.
%
Inverter losses: typically 85%.
W
The most the station can deliver.
What's plugged in

Hours: how long each device actually draws power in 24 hours.

  • Wi-Fi router
    W
    pcs
    h
  • Fiber modem (ONT)
    W
    pcs
    h
  • Laptop
    W
    pcs
    h
  • Refrigerator
    W
    pcs
    h
  • LED bulb
    W
    pcs
    h
  • Gas furnace blower
    W
    pcs
    h
  • Phone charger
    W
    pcs
    h

The station will run for about

3 h 33 min

Average load 245 W · 5.88 kWh per day

Usable energy
870 Wh
Everything at once
1 h 11 min
no breaks
Peak power
735 W

What drains the station most

  • Gas furnace blower61% · 3,600 Wh per day
  • Refrigerator20% · 1,200 Wh per day
  • Laptop7% · 390 Wh per day
  • Wi-Fi router5% · 288 Wh per day
  • Fiber modem (ONT)3% · 192 Wh per day

You'll gain the most by switching off “Gas furnace blower”: the station will last 5 h 37 min longer.

How runtime is calculated

First, usable energy: station capacity × the share that reaches the outlets. For a 1,024 Wh station at 85%, that's about 870 Wh.

Next, the average load. A 150 W refrigerator doesn't draw 150 W all the time: its compressor runs about a third of the time. So for each device we take watts × hours of use per day and divide the total by 24.

Runtime = usable energy ÷ average load. A router, fiber modem, laptop, refrigerator, three LED bulbs, a gas furnace blower and two phone chargers average about 240 W, so a 1,024 Wh station lasts roughly 3½ hours.

What drains a station fastest

Usually not the most powerful device but the one that runs longest. A furnace blower cycling on and off all day uses more energy than a coffee maker you run for five minutes. The calculator shows each device's share and how much longer the station lasts without it.

How to make a station last longer

  • Switch the AC inverter off when nothing needs 120 V: it draws 10–30 W on its own.
  • Run the router and modem from the 12 V or USB-C port to skip inverter losses.
  • Charge laptops and phones from USB-C rather than through their wall adapters.
  • Keep the refrigerator closed: it holds the cold longer and starts the compressor less often.
  • Not sure which station you need? Try the backup power planner.

Frequently asked questions

What does capacity in Wh mean?

Watt-hours are stored energy. A 1,024 Wh station could in theory run a 1,024 W device for one hour, or a 102 W device for ten. In practice about 85% of that reaches the outlets because of inverter losses.

Why does the station run shorter than capacity ÷ watts?

The inverter turns the battery's DC into 120 V AC and loses 10–15% of the energy doing it. It also draws 10–30 W itself whenever it's on, even with nothing plugged in. That's why the calculator starts from usable energy, not the number on the case.

How long will a router run on a power station?

A router and fiber modem together draw about 20 W. A 1,024 Wh station with roughly 870 Wh usable runs them for around 43 hours. Powering them from the station's 12 V or USB-C output avoids inverter losses entirely.

Can a power station run a gas furnace?

Often, yes — the furnace burns gas, but its blower fan and controls need electricity. Blowers draw 300–800 W and briefly more to start, so check the station's surge rating. Many furnaces also need a pure sine wave inverter and a proper transfer switch or furnace plug.

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