What Size Generator You Need to Run a Refrigerator and Freezer

Start with the wattage your appliances actually draw

A refrigerator and freezer together typically need a generator rated between 5,000 and 7,500 watts to run safely. The exact size depends on whether you are running them at the same time, what model you own, and whether you want to run other things too. Most home refrigerators draw 600 to 800 watts while running, and most freezers draw 500 to 700 watts. The catch is that both appliances use a starting surge — a brief spike in power when the compressor kicks on — that can be two to three times their normal running wattage.

Your generator must handle both the running wattage and the surge. If you buy a generator rated only for running watts, it will shut down or fail the moment the compressor starts. Check your appliance manual or the nameplate on the back for the actual wattage your model uses. If you cannot find it, contact the manufacturer with your model number — they will give you the exact figure in minutes.

A 5,000-watt generator is the practical minimum for a refrigerator and freezer running together. A 7,500-watt generator gives you headroom and lets you run a light, charge a phone, or power a small space heater at the same time without risk. Anything smaller than 5,000 watts will struggle or fail.

Key Takeaways

• A 5,000 to 7,500-watt generator is needed to run a refrigerator and freezer together, because both appliances draw surge power when the compressor starts.
• Check your appliance manual or the nameplate on the back for the actual running wattage and starting surge — do not guess based on age or size.
• A 5,000-watt generator is the minimum; a 7,500-watt generator gives you safety margin and lets you run other small appliances during an outage.
• Portable gas generators work for short outages, but for extended power loss, a permanently installed standby generator is more reliable and requires less fuel management.

How to calculate the wattage you actually need

Start by finding the running wattage for each appliance. Look on the back of the refrigerator or freezer for a label that lists amps and volts. Multiply amps by volts to get watts. For example, if a refrigerator draws 6 amps at 120 volts, that is 720 watts running. Write down the running wattage for both appliances.

Next, find the starting surge for each. The manual usually lists this as "locked rotor amps" or "inrush current." Multiply that number by 120 volts to get the surge wattage. A typical refrigerator might have a locked rotor amps rating of 15, which equals 1,800 watts at startup. A freezer might be 12 amps, or 1,440 watts at startup.

Add the running wattage of both appliances together — that is your baseline. Then add the starting surge of whichever appliance has the larger surge. This gives you the peak wattage your generator must deliver. In the example above: 720 (fridge running) + 600 (freezer running) + 1,800 (fridge surge) = 3,120 watts. A 5,000-watt generator handles this comfortably and leaves room for error or future appliances.

Portable gas generators versus standby units

A portable gas generator is what most people think of first. You can buy one for $500 to $2,000, store it in a garage, and wheel it out when the power goes down. They run on gasoline or propane and start within minutes. For a refrigerator and freezer, you need at least 5,000 watts; a 6,500 or 7,500-watt model is safer and more practical. Portable generators are loud — typically 70 to 90 decibels — and they need fuel on hand. You must run them outdoors, away from windows and doors, because they produce carbon monoxide.

A standby generator is permanently installed outside your home, usually near the electrical panel. It runs on natural gas or propane from your existing line, starts automatically when power fails, and switches your home's circuits to generator power without you doing anything. Standby units cost $3,000 to $15,000 installed, but they run quietly, need no fuel storage, and keep your refrigerator and freezer running indefinitely. They are the choice if you live in an area with frequent or extended outages.

For most homeowners, a portable 5,000 to 7,500-watt generator is the practical starting point. It handles a refrigerator and freezer plus a few other essentials, costs less upfront, and takes up little space. If outages last more than a few hours in your area, or if you want the appliances to run without your attention, a standby unit is worth the investment.

Fuel type and runtime

Portable generators run on gasoline, propane, or both. Gasoline is cheaper and easier to find, but it degrades after 30 days of storage and can gum up the carburetor if the generator sits unused. Propane lasts indefinitely and burns cleaner, but propane generators are heavier and more expensive. A dual-fuel model lets you switch between the two.

Runtime depends on fuel tank size and load. A 5,000-watt generator with a 5-gallon gas tank running at half load (refrigerator and freezer) typically runs 8 to 12 hours on a full tank. A propane model with a 20-pound tank runs 12 to 20 hours at the same load. If you expect an outage to last more than a day, you need either extra fuel on hand or a way to refuel quickly. Many people keep two 5-gallon gas cans filled and stored safely in a shed or garage.

For a standby generator, fuel is not a concern — it draws from your home's natural gas or propane line and can run indefinitely as long as the utility supply is on. This is one reason standby units are preferred in areas prone to long outages.

Connecting your generator safely

Never plug appliances directly into a portable generator using household extension cords. Instead, use a heavy-duty outdoor-rated extension cord rated for the wattage you are drawing — at least 12 gauge wire for a refrigerator and freezer. Better yet, use a generator transfer switch, which is a panel that sits between your generator and your home's electrical panel. It lets you safely switch circuits from grid power to generator power without backfeeding electricity into the utility lines, which can injure utility workers.

If you do not have a transfer switch, plug appliances one at a time into the generator using a heavy-duty cord. Start with the refrigerator, let it run for a minute, then plug in the freezer. This staggers the startup surges and prevents the generator from overloading. Never run both appliances on the same extension cord — the cord will overheat and create a fire risk.

For a standby generator, a licensed electrician installs the transfer switch and connects the unit to your home's panel. This is not a DIY job — improper installation can damage your appliances or create a serious shock hazard.

Choosing between running both appliances or just one

If you have limited generator capacity or budget, you may need to choose which appliance to prioritize. A refrigerator is usually more important because it keeps food safe for several days, while a freezer can hold temperature for 24 to 48 hours if you keep the door closed. If you have a 3,000 to 4,000-watt generator, you can run a refrigerator alone, but not both appliances together.

If you must choose, run the refrigerator and let the freezer sit idle. Keep the freezer door closed to preserve the cold. Once power is restored, the freezer will return to safe temperature within a few hours. If you have a separate chest freezer in a garage or basement, it will stay cold longer than an upright model because cold air does not spill out as quickly when you open it.

The best solution is to size your generator for both appliances from the start. A 5,000-watt unit is not much more expensive than a 3,000-watt model, and it gives you the flexibility to run other essentials during an outage.

Maintenance and testing

A portable generator sitting unused for months will not start reliably when you need it. Run it under load for 20 to 30 minutes every month or two. Connect your refrigerator and let it run, or use a load bank if you have one. This keeps the fuel system clean and the engine in working order. Change the oil every 50 to 100 hours of use, and replace the spark plug annually.

Store gasoline in approved metal cans in a cool, dry place away from your home. Add a fuel stabilizer if you plan to store gas for more than a month. Drain the tank and run the generator dry before storing it for the winter. Propane does not degrade, so propane generators need less maintenance — just check the tank level and run the unit occasionally to keep it ready.

For a standby generator, the utility company or the manufacturer usually handles maintenance as part of a service contract. The unit runs a self-test once a week and alerts you if something is wrong. Have a licensed technician inspect it annually.

Frequently Asked Questions

Can I run a refrigerator and freezer on a 3000 watt generator?

No. A 3,000-watt generator is too small for both appliances running together. The starting surge alone will exceed the generator's capacity and cause it to shut down or fail. A 3,000-watt generator can run a refrigerator alone, but not a freezer at the same time.

What if I run the refrigerator and freezer at different times?

If you turn off one appliance before starting the other, a smaller generator may work. However, this is impractical during an outage — you want both appliances running to preserve food. A 5,000-watt generator eliminates this problem and costs only a few hundred dollars more.

Do I need a transfer switch if I use an extension cord?

A transfer switch is the safest option, but if you do not have one, use a heavy-duty outdoor-rated extension cord rated for at least the wattage you are drawing. Never plug multiple appliances into the same cord, and never backfeed power into your home's electrical panel by connecting the generator to an outlet. This creates a shock hazard for utility workers.

How long will a freezer stay cold if the power goes out?

A full freezer will stay at safe temperature for 24 to 48 hours if you keep the door closed. A half-full freezer will warm up faster. If you have a generator, you can run it to keep the freezer cold indefinitely. If you do not have a generator, keep the door closed and avoid opening it until power is restored.

Is a standby generator worth the cost?

A standby generator costs $3,000 to $15,000 installed, but it runs automatically, needs no fuel storage, and keeps your refrigerator and freezer running indefinitely during an outage. If you live in an area with frequent or extended power outages, or if you want peace of mind, it is worth the investment. For occasional outages, a portable generator is more cost-effective.