Outage Power Planner

Backup power calculator

Estimate how long a portable power station can run your devices during an outage, and whether it can handle their running and startup power. Everything is calculated in your browser.

1. Choose your devices

Set a quantity for each device you want to run. Values are Estimate generic examples – open Adjust values to enter the numbers from your own device label or power meter.

  • Refrigerator (full-size)~150 W running · ~1200 W startup · 40% usage
    Adjust values

    Compressor cycles on and off. Startup surge can be several times the running draw.

  • Chest freezer~80 W running · ~800 W startup · 40% usage
    Adjust values

    Cycles like a refrigerator. Keep the lid closed during an outage.

  • Microwave oven~1500 W running · ~1800 W startup · 3% usage
    Adjust values

    Input power is higher than the advertised cooking power. Default usage ≈ 45 min per day.

  • Wi-Fi router + modem~20 W running · ~20 W startup · 100% usage
    Adjust values

    Small, steady load that runs all the time.

  • LED TV (about 50")~100 W running · ~100 W startup · 100% usage
    Adjust values

    Draw depends heavily on screen size and brightness.

  • Laptop charger~60 W running · ~60 W startup · 100% usage
    Adjust values

    Draw drops once the laptop battery is full.

  • Phone charger~10 W running · ~10 W startup · 100% usage
    Adjust values

    Many phones can also charge from the station’s USB ports.

  • Box fan~75 W running · ~150 W startup · 100% usage
    Adjust values

    Varies with speed setting.

  • Electric space heater~1500 W running · ~1500 W startup · 50% usage
    Adjust values

    Very high draw – drains most portable batteries quickly. Never leave unattended.

  • LED light bulb~10 W running · ~10 W startup · 100% usage
    Adjust values

    Roughly a 60 W-equivalent LED bulb.

  • CPAP machine (no humidifier)~40 W running · ~40 W startup · 33% usage
    Adjust values

    Default ≈ 8 h per day. Heated humidifiers add a lot. Confirm with your device supplier and doctor.

    Medical equipment: do not rely on this estimate. Confirm power needs and backup plans with your doctor and device supplier.

2. Your power station

Presets are Estimate generic capacity classes, not real products. Enter the ratings printed on your station or in its manual.

Advanced assumptions

Defaults are conservative general assumptions. See the methodology.

3. Estimated results

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Estimated runtime—
Average load
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Energy per 24 h
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Usable energy
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Devices selected
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Running load vs. continuous rating—
Startup peak vs. surge rating—

    Estimate only. Real runtime depends on your exact devices, temperature, battery age and how often motors cycle. Leave a safety margin.

    Est. runtime—

    How to get a more accurate estimate

    • Use your own numbers. Check the rating label on each device (watts, or volts × amps) or measure it with a plug-in power meter over 24 hours. Open Adjust values to enter them.
    • Use your station’s real ratings. Capacity (Wh), continuous AC output (W) and surge output (W) are listed in its manual or on its label.
    • Plan for less. Cold weather, an aging battery, or a fridge door that is opened often will reduce runtime. A 20–30% margin is a sensible habit.

    Want to know exactly how the numbers are produced? Read the methodology.