How Long to Run a Generator to Keep Fridge Cold

Power outages can strike at any time, whether from severe storms, flooding, or civil unrest. Regardless of why you lost power, you want to make sure that your food stores will be fresh.

That’s why it’s important to have a backup generator so you can run your refrigerator if you happen to lose power, even if that’s only for an hour.

But how long do you run a generator to power a full-sized refrigerator?

In short, your refrigerator doesn’t have to be running the whole time the power is out to keep your food fresh. Because most modern fridges are designed to conserve energy, you should be able to run your generator for 20 minutes to keep your fridge cool for up to an hour.

Of course, you can always adjust this time as needed based on how much food you have in your fridge, how much fuel you have for your generator, and plenty of other factors. Keep reading to find out how a few specific factors can impact how long to run a generator for a refrigerator to keep your food cold.

Why Should You Worry About Keeping Your Fridge Cold?

It’s pretty much a no-brainer, but food that requires refrigeration goes bad fairly quickly if it’s not stored in the right conditions. For example, leaving milk out on the counter for more than two hours at room temperature will cause it to spoil.

As a general rule, the USDA recommends that any food that has been left out for more than two hours at room temperature—or less time at higher temperatures—be thrown away. There are many kinds of bacteria that start growing on food and drinks between 40 °F and 140 °F, including Salmonella Enteritidis, E-coli, and many others.

During a power outage, if you don’t open your refrigerator, your food will stay safe for up to 4 hours. But after that, you start to venture into that danger zone range of temperatures, where food will start to spoil in your fridge without power.

If you’re an avid homesteader or prepper, you might only have a few bare essentials in your fridge. Eggs, milk, some condiments; the norm. Your main stockpile will be in dried goods and things that don’t require power to keep.

If this is the case, then we would recommend having a few cooler bags or insulated travel containers at the ready. It’s much easier to keep things cool when they are closer together because the proximity of the items helps keep all of them cool.

That’s why if your fridge has only a few items in it, it’s better to group them together in a cooler bag with some ice and a cool pack than to try to run your fridge with a generator.

But, if you’re not the homesteading type, and your fridge has all kinds of perishable goodies in it, we’ll show you how to make sure your groceries are just as good after the power outage as they were before.

How Much Power Does a Refrigerator Require?

The power required to start and run a refrigerator vary depending on the:

  • Age
  • Size
  • Condition

Obviously, older models take a lot more power to run, and if your refrigerator has been heavily used (like the seals around the door are wearing out), it will be less efficient as well.

Starting a refrigerator takes the most power because the compressor requires a big jolt of energy to get going. After the compressor has started, the running wattage for the refrigerator becomes significantly less.

Here’s a little bit of a breakdown of the power required to start and run various refrigerator sizes:

SizeStarting WattsRunning Watts
Large Refrigerator (25+ cubic ft.)1000-1200 watts200-400 watts
Average Refrigerator (20 cubic ft.)700-1000 watts100-250 watts
Small Refrigerator (10-20 cubic ft.)400-600 watts75-150 watts
Mini Fridge (5 cubic ft. or less)80-120 watts40-50 watts

Choosing a Generator

So now that we know how much power is required to run a refrigerator, we can do some calculations to find out what kind of generator you need.

As a rule of thumb, companies that manufacture generators for home or business use rate the output as Watts or KiloWatts, which will make it easy to find out what generator is large enough for your home.

Let’s say that you live in a relatively small home, with a small refrigerator, a few lamps, and a couple of other small appliances. In total, your home Wattage might add up to around 3000 Watts.

We suggest purchasing a generator that produces a good deal more Watts than you require, that way if you ever forget to add any device or appliance into your calculation, you have some wiggle room. So for our example above, you’re want to purchase a 5kW generator. That way, you know for sure that your generator will power your refrigerator and your lights.

If you’re looking to purchase a generator to run your home during emergencies or to keep your food fresh during a power outage, here are some of the best brands that money can buy:

  • Honda
  • Generac
  • Westinghouse
  • Champion
  • Ryobi

Powering Your Refrigerator With A Generator

As mentioned earlier, there are many considerations that go into deciding how long to run a generator to power a refrigerator.

A good rule of thumb is that 1 hour of generator time will keep your food cold for up to 4 hours. This amount of time will vary depending on the integrity of the seals around your refrigerator.

If you have an older unit, and the seals on the door are cracked or peeling away, you might want to take some time to seal the door as much as possible. Using duct tape, you can easily create an airtight seal, or as close to airtight as possible. This will help to keep cold air from escaping while the fridge is running, thus lowering how long you have to keep the generator running.

Of course, you can always choose to run your generator for the full duration of the power outage. For example, the Westinghouse WGen9500DF can run for up to 12 hours on 6.6 gallons of fuel. If you’re not worried about fuel usage, you can certainly run the generator for as long as you need it.

But, if you happen to be running short on gas or propane, running on a 1:4 ratio is the best method for preserving the food in your refrigerator.

How Do I Attach My Refrigerator To My Generator?

If you’ve never used a generator before, hooking it up to your appliances—including your refrigerator—might seem like a daunting task.

There are two ways you can connect your appliances to a generator:

  1. You can have an electrician install a transfer switch to your circuit box. This allows you to attach your generator directly to your house without having to run extension cords from your appliances to the generator. It also protects your appliances from power surges or being overloaded when the generator starts up.
  2. Alternatively, you can use extension cords that plug directly into the generator. You want to make sure you’re using heavy-duty outdoor cords, and only use cords that are rated for the loads of your appliances. You should never use a damaged extension cord or one that’s not rated for the power you’re sending through it.

Tips for Running a Generator

  • Never run a generator indoors. Always make sure there’s ample space for the generator to run, at least three to four feet all around it. The generator puts off exhaust just like any other fuel-burning device, so keeping it in an enclosed space will result in a build-up of carbon monoxide.
  • When your generator runs out of fuel, make sure to let it cool down before you refuel it. Just like your car hood is hot to the touch after you take a 7-hour road trip, your generator engine will be just as hot. Let it cool down to where you can safely touch it with your hand before adding more fuel.
  • Test your generator from time to time. For the handy people out there, you’ll probably use your generator on a regular basis for running power tools, camping, or other outdoor activities. But, if you bought one just to have, make sure you run it at least once a month to ensure everything is in working order.
  • Keep a good amount of fuel on hand. It’s easy to fill up your lawnmower or weed eater and forget to refill your gasoline tank. Always make sure you have a fresh spare tank somewhere around your house because you never know when you’ll need it!

Common Questions About Generators

Can a generator damage my refrigerator?

Yes, if you’re not careful and match the voltage range from the generator with the voltage range from the refrigerator, you could end up blowing out your fridge. Not only will you have to repair the fridge, but you’re also creating a fire hazard in the process. That’s why it’s best to use a transfer switch so you can avoid overloading any one appliance.

How much does a good generator cost?

It depends on how powerful you need it to be. Generators typically follow a price-per-Watt range. For a smaller, lower-Wattage generator, you can expect to pay between $500 and $900, while more powerful generators can cost well over $1,000.

How do I use a generator to power my house?

During a power outage or an emergency, you can use a generator to keep the lights on and the fridge running. We recommend installing a transfer switch, but you can always run multiple extension cords from your generator to your lamps/appliances.

Just be careful not to overload your appliances with a powerful generator. It’s like putting a low-watt lightbulb in a high-watt lamp; you’re going to burn it out.