What size power station do I need for a power cut in the UK?

List what you want to keep running, multiply each device wattage by the hours you need it, add the totals and divide by 0.85 to allow for inverter losses. A typical evening cut running a router, lights and phone charging needs 300 to 400Wh. Keeping a fridge going for a day needs roughly 1,000 to 1,200Wh.

Are the wattage figures in this calculator exact?

They are typical figures for common UK household devices, useful for sizing. Your own equipment may differ, so check the label or power supply of anything critical, especially medical devices, and size with a 20 per cent margin.

Power Station Size Calculator UK: What Size Do I Need?

Tick what you would genuinely keep running in a power cut, set the hours, and the calculator does the honest arithmetic: device watts, multiplied by hours, divided by 0.85 for inverter losses, plus a 20 per cent margin. Typical UK figures; check the label on anything critical.

What the result means

Under 300Wh: a compact unit covers you: phones, router, lights and a CPAP without humidification. See the compact picks in our budget power stations guide.
300 to 800Wh: the comfortable evening-cut class for most households. Compare the mid-size picks in the main buyer's guide.
800 to 1,500Wh: fridge-through-the-day territory. You want the 1kWh class: see Best Overall and Best for Families in the buyer's guide.
Over 1,500Wh: long rural cuts or multi-day resilience. Look at the Best for Long Cuts pick, and plan solar recharging with the solar generators guide.

The honest caveats

These are typical figures for sizing, not a promise about your exact kit. Anything with a heating element (kettles, heaters, electric showers) is out of reach of every portable unit, which the buyer's guide explains with the full maths. For medical equipment, check the device label, size generously, and register with your network operator's Priority Services Register as described in our power cut guide.

What size power station do you need?

What the result means

The honest caveats