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What Size Generator to Run a Freezer or Refrigerator?

In this article, I will help you determine what size generator to run a freezer or refrigerator. In addition, learn how to choose the best generator with enough power output for all your household appliances.

A power outage ruins your day if it lasts for a long time.
Even though you keep the fridge door closed to conserve cool air, your food begins to warm and you’re stuck in a dilemma.

Should you start transferring the food from your refrigerator or deep freezer to an ice chest?
Do you wait for the power company to restore power before your food defrosts and spoils?

The ideal solution to the various problems caused by power outages is a home generator.

What size generator to run a refrigerator freezer?

The right size generator to run a freezer or refrigerator depends on the power requirements of the appliance and any other devices you may want to run simultaneously during a power outage.

Generator Size for Common Refrigerator Freezer Types

Lets dive into this a bit deeper.

Determine Power Requirements

Before you invest in a portable generator for home use, an inverter generator, or standby generator you must understand the power requirements of your electric appliance.

The power needs of your fridge are determined by two key metrics: running watts and peak watts.

Running Watts vs Starting Watts

Running watts and starting watts are two important specifications that describe the power requirements of electrical home appliances and devices.

More specifically, this information determines the type of generator and size of generator you need.

Understanding the difference between these two values is crucial when selecting a generator to ensure it can meet the power needs of your equipment.

Running watts refer to the amount of power needed to keep the refrigerator running.

Peak watts signify the extra power necessary during the initial startup and anytime the refrigerator kicks into cooling mode.

Keep in mind, the peak watts can be three to five times higher than the running watts due to the additional power required to operate the refrigerator’s compressor.

Power Consumption of Different Refrigerators

Refrigerators vary in their power consumption based on their energy efficiency, size, and design.

Modern refrigerators, particularly those with an energy star rating, are generally more energy-efficient handling external loads, requiring less powerful generators to function.

For instance, recent models typically need between 100 to 200 running watts per hour, while older models may require up to 800 running watts.

Given that peak watts are estimated at three to five times the running watts, the energy efficiency of the refrigerator significantly impacts the generator size and fuel usage.

Interestingly, the style of the refrigerator also influences energy efficiency.
Top mount freezers tend to be more energy-efficient than under-mount freezers or side-by-side designs.

Furthermore, older appliances use more power while newer appliances use less power.
Mini fridges, popular for camping, use around 50 running watts.

If your refrigerator or chest freezer consumes a large amount of electricity, a bigger generator will be required

How To Determine the Best Generator to Run a Freezer

The size of the generator you need to run a freezer or refrigerator depends on the power requirements of the appliance.

Moreover, this includes any other devices you may want to run simultaneously during a power outage.

To determine the generator size, follow these steps:

Consider a margin of safety: It’s a good idea to have some extra capacity in your generator to account for variations in power consumption and to ensure it operates comfortably within its rated capacity. A 10-20% margin is often recommended.

Fuel type and runtime: Choose a generator that runs on a fuel type you have access to, such as gasoline, propane, or diesel. Consider how long you may need to run the generator during a power outage and ensure it has an appropriate fuel capacity and runtime.

1 – Determine Your Refrigerator’s Power Requirements

To determine the power requirements of your refrigerator or freezer, determine the running watts and starting watts.

Calculate the Running Watts

refrigerator label example

First, look for an energy label on the back or side of your freezer or refrigerator to obtain the wattage rating.
If you cannot find the label, refer to the user manual.

The label typically specifies a model number, voltage/frequency values, and rated current.
Find the voltage (v) and current (A) on the label.

To get the running watts of your refrigerator, simply multiply the voltage by the current to determine power using the following equation:

Power = Voltage x Current

For example, if the voltage is 127v and the rated current is 2.4A, the running watts would amount to 304.8 watts.
304.8 = 127 x 2.4

Calculate the Starting Watts (Surge Watts)

refrigerator label example

To calculate the starting wattage of your fridge, you need to find a label on the compressor. 

The label should have a number expressed in A (Amperes).
Keep in mind, it is sometimes referred to as “Locked Rotor Amp” (LRA) or “Full Load Amperes”. 

Essentially, this represents the higher current needed when the compressor turns on.
If the refrigerator compressors label also features a voltage value, multiply that voltage by the amps. 

Conversely, if the label lacks a voltage value simply use the voltage value you used to calculate running watts. 

Peak Watts = Voltage * Full Load Amperes

For instance, if the voltage is 127v and the amps is 6.5A, the peak watts of power would be 825.5.
127 * 6.5 = 825.5

If you only need a generator to power a refrigerator used in this example, the generator needs to be capable of:

Running Watts: 304.8
Starting Watts: 825.5

2 – Determine Additional Power Needs

If you intend to use other electrical appliances with electric motors like a sump pump, air conditioner, mini fridge, or microwave oven remember to add those running watts.

Also, this includes power stations and other small appliances
Moreover, this computes the minimum running wattage requirement of your generator.

Add 25% Overhead

As mentioned, including extra capacity in your wattage calculation accounts for variations in power consumption and growth.

As a general rule of thumb, add 10%  for variations in power to ensure it operates comfortably within its rated capacity.

Furthermore, add 15% for the future appliance purchases protects your generator investment.

While not required, I suggest adding 25% to you final wattage number.  Obviously, generating too much power during a power outage is better than not enough.

To calculate the surge wattage requirement, take the largest surge watt of all your essential appliances and multiply that number by 1.25 to build in some buffer.

Running Watts: 304.8 * 1.25 = 381
Starting Watts: 825.5 * 1.25 = 1,031.8

3 – Size the Power Generator

Once you have the total wattage requirements for all devices you want to power and added the additional 25% in overhead, choose a large enough generator to handle the peak power demand. 

Generators are typically rated based on running and peak watts (e.g., 2,000 watts, 5,000 watts, etc.).

So, the generator you select should have a peak power (surge) rating that exceeds the combined starting wattage of all connected devices.

Obviously, this principle also applies to the running watts.

Common Sense

Not every appliance requires peak watts. 

Appliances such as coffee makers, space heaters, and phone chargers draw power at a consistent rate. 
However, if you’re running an air conditioner, washing machine, small refrigerator, or sump pump, you need to know their peak watts to correctly size your generator.

To size a generator for multiple appliances, add up the running watts of those appliances to get the total running watts. 

4 – Choose the Best Generators to Run a Freezer

Different types of generators, like refrigerators, are rated based on running and peak watts.

Knowing the running and peak watts of your refrigerator makes it easy to determine the size of the generator with enough output power to power it. 

Again, if you plan to run other appliances along with the refrigerator, your generator should accommodate the power requirements of all those appliances simultaneously.

As stated, refrigerators and freezers come in various types and sizes, and their power requirements can vary significantly based on factors like size, brand, and features. 

Here are some of the most common types of refrigerator freezers along with approximate starting watts and running watts:

Please note that these are rough estimates, and the actual power requirements can vary based on the specific model, size, and efficiency of the appliance. 

To determine the exact power consumption of your refrigerator or freezer, you should check the manufacturer’s label or user manual, which typically provides information on the appliance’s electrical requirements.

Top-Freezer Refrigerator or Bottom-Freezer Refrigerator

  • Starting Watts: 800-1200 watts
  • Running Watts: 100-800 watts

Honda EU2200ITAN 2200-Watt 120-Volt Super Quiet Portable Inverter Generator with CO-Minder

Side-by-Side Refrigerator or French Door Refrigerator

  • Starting Watts: 1000-1500 watts
  • Running Watts: 100-800 watts

Generac 8251 GP2500i 2500-Watt Portable Generator

Compact/Mini Fridge

  • Starting Watts: 100-400 watts
  • Running Watts: 50-100 watts

Jackery Portable Power Station Explorer 500, 518Wh Outdoor Solar Generator Mobile Lithium Battery Pack with 110V/500W AC Outlet (Solar Panel Optional) for Home Use

For more generator recommendations, be sure to visit our best home generators for power outages article.

Inverter Generator vs Regular Generator

Inverter generators and regular generators both serve the purpose of generating power but differ in the way they operate.

While both can be used as home generators for power outages, one may be the best option for you..

Regular generators, also known as conventional or traditional generators, use a mechanical alternator to produce AC (alternating current) electricity. 

They typically run at a constant speed, usually 3600 RPM (revolutions per minute), regardless of the electrical load.

Inverter Generators, on the other hand, employ a different technology. 

They generate AC power like regular generators.
However, this power is then converted to DC and then inverted back to clean AC power.
Essentially, this mimics the power you get from a standard electrical grid. 

Lets briefly compare an inverter generator to a regular generator.

Output Quality

  • Regular Generator: Conventional generators provide relatively stable AC power but may have fluctuations in voltage and frequency, which can be problematic for sensitive electronics and appliances.
  • Inverter Generator: Inverter generators produce high-quality, stable AC power with minimal voltage and frequency fluctuations. This makes them suitable for powering sensitive electronic devices like laptops, smartphones, and televisions.

Fuel Efficiency

  • Regular Generator: Traditional generators run at a constant speed, which can be inefficient when the electrical load varies. They may consume more fuel than necessary, especially when running at lower loads.
  • Inverter Generator: Inverter generators automatically adjust their engine speed to match the electrical load, resulting in better fuel efficiency. They consume less fuel when running at lower loads, making them more cost-effective over time.

Size and Portability

  • Regular Generator: Conventional generators are often larger, heavier, and less portable than inverter generators. They are typically used as standby generators and require a dedicated installation location.
  • Inverter Generator: Inverter generators are more compact and lightweight, making them highly portable. They are suitable for various applications, including camping, tailgating, and backup power for homes.

Noise Level

  • Regular Generator: Traditional generators tend to be noisier because they run at a constant speed, which generates a constant level of noise.
  • Inverter Generator: Inverter generators are designed to be quieter. Their variable-speed engines can adjust their RPM based on the load, reducing noise levels when running at lower loads.


  • Regular Generator: Conventional generators are often less expensive upfront than inverter generators of the same power output.
  • Inverter Generator: Inverter generators are generally more expensive initially due to their advanced technology, but they can save money in the long run due to their increased fuel efficiency and reduced maintenance costs.


In conclusion, learning what size generator to run a freezer or refrigerator is a relatively straightforward process. 

Remember, size up slightly in case you want to power multiple things simultaneously.
Overloading a generator can trip its circuit breaker.
Older generators without modern safety features might even combust and pose a fire hazard when overloaded.

Other factors to consider when shopping for generators include fuel type, noise level, and whether you plan to run sensitive electronics. 
An inverter generator might be a more suitable option for you than conventional generators for such needs.

Most importantly, follow safety guidelines and operate generators in a well-ventilated area to prevent carbon monoxide poisoning. 

Additionally, consult the manufacturer’s instructions and guidelines for your specific generator model to ensure safe and reliable operation. 

If you’re unsure about the power requirements of your appliances or the right generator size, consider consulting an electrician or generator specialist for assistance.

Related Posts:

What size generator do I need to power my refrigerator and freezer during a blackout?

For a conventional refrigerator and freezer combo, a 2,000-watt generator should suffice.

Can I run my central air conditioner with a home generator?

Yes, but central AC units typically require larger generators capable of 5,000 to 7,000 watts.

Will a portable generator power all my essential home appliances simultaneously?

Yes, if the generator is capable of producing enough wattage to handle all your home appliances at the same time. Prioritize necessities like the fridge, lights, and a sump pump, and use a generator with adequate wattage.

Can I connect a standby generator directly to my home’s electrical system?

Yes, a standby generator can be directly connected to your home’s electrical system. However, this requires a transfer switch and proper installation by a qualified electrician for safety and compliance reasons.