How long will my fridge run on a power station?

By our math, a box that holds about 1,000 watt-hours runs a fridge for about 7 hours. That math acts as if the fridge runs the whole time, so many fridges will last longer. Watt-hours: how much power a box holds.

The easy math

Our tools count 120 watts for a fridge. Watts: how fast something uses power.

Take the box size in watt-hours. Keep 85% of it, because some power is lost inside the box. Then divide by 120.

1,024 Wh × 0.85 ÷ 120 W = 7.3 hours

That is the Anker SOLIX C1000 Gen 2, a box of about 1,000 watt-hours.

Estimates. Your devices may use more or less.

Hours by box size

The first column of hours is our simple math at 120 watts. The second uses 54 watts, a day-long average we explain below.

Box size	Fridge at 120 W, never resting	Fridge at a 54 W average
300 Wh	2.1 hours	4.7 hours
500 Wh	3.5 hours	7.9 hours
1,000 Wh	7.1 hours	16 hours
2,000 Wh	14 hours	31 hours

Hours are only half the story. A box must also be able to start the fridge, which we cover below. Do you want to run more than a fridge? Our Find My Power tool adds up your whole list. We read every box size on the maker's own page, and this is how we check each number.

Why your fridge may last longer

A fridge does not work the same way all day. Frigidaire says every compressor cycles on and off. It also says some models are built to run nonstop, and that a warm room or an open door makes a fridge run more.

So we looked at a whole year. On October 5, 2026, the EPA's list of ENERGY STAR certified fridges had 2,628 full-size fridges with a freezer. Their use ran from 121 to 805 kilowatt-hours a year. The middle one used 473.

473,000 Wh ÷ 8,760 hours = 54 W

By our math that is 54 watts on average, less than half of our 120. Your fridge may not be on that list. So treat 54 watts as the hopeful number and 120 watts as the more careful one. Some fridges pull more while the motor is on: Honda's generator guide lists 132 to 192 watts for a running ENERGY STAR fridge or freezer.

To find your own number, look for the yellow EnergyGuide label. The FTC says that label tells you how much energy an appliance uses. If yours shows kilowatt-hours for a year, multiply by 1,000 and divide by 8,760.

The start-up burst

A fridge needs extra power for a moment when its motor starts. Surge: a short burst some things need to start.

Our tools count 1,200 watts for that burst. The number comes from Honda's generator guide, which lists about 1,200 watts to start an ENERGY STAR fridge or freezer. Generac says the burst is typically 2 to 3 times the running watts, which would be less. We use the higher number to stay on the safe side.

This is why a small box can fail to start a fridge even when the hours look fine. By our math, a box whose surge stops at 600 or 1,000 watts does not start a fridge. A box with a surge of exactly 1,200 watts starts it only when nothing else is plugged in. Find My Power runs this check for you.

So read the surge or peak number on the box, not just its size. Anker lists 2,000 W of output and a 3,000 W peak for the C1000 Gen 2. That is well above 1,200.

Our guide to watts vs. watt-hours shows how to check both numbers.

How long food stays safe with no power

You may not need a box for a short outage. The USDA says a closed fridge keeps food safe for up to 4 hours. It says a full freezer holds its temperature for about 48 hours, or 24 hours if it is half full.

After that, cold food is at risk. Ready.gov says to throw out food that has been at 40 degrees or higher for two hours or more. A box helps most when the outage lasts longer than that.

Make it last longer

The first four tips come from the USDA page above.

• Keep the fridge and freezer doors closed.
• Group foods together. This helps them stay cold longer.
• Keep the freezer full. Fill empty spaces with frozen jugs of water.
• Keep a thermometer in the fridge. You want it at 40 °F or below.
• Plug in only what you need. By our count Wi-Fi adds 15 watts, and a space heater adds 1,500.

For a long outage, a fridge is one part of a bigger list. See our guide to backup power for a whole home.

Questions people ask

Can a 300 watt-hour box run a fridge?

Not well. By our math it holds about 2 hours of fridge time. And our tools count 1,200 watts to start a fridge, so a small box with a 600-watt or 1,000-watt surge does not pass. A box near 1,000 watt-hours gives you more room. You can compare two boxes or see our picks.

What size box runs a fridge for 24 hours?

By our simple math, 120 watts for 24 hours needs about 3,388 watt-hours. At a 54-watt average it needs about 1,525.

How do I find my fridge's watts?

Look at the nameplate inside the fridge. Generac says to multiply the volts by the amps printed on it. Our guide to what a watt-hour is shows what to do with that number.

Is food safe to eat after the power comes back?

The USDA says to throw out meat, milk, eggs and leftovers if the fridge had no power for more than 4 hours. Never taste food to check it. When in doubt, follow the USDA page linked above.