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What Size Generator to Run Refrigerator and Freezer (Calculator)

Refrigerators and freezers are among the essential appliances that need backup power during an outage. However, they are among the high-power units that make sizing a generator difficult. So, what size generator is ideal for running a refrigerator and a freezer?

Different refrigerators and freezers sizes and brands require different amounts of power to start and run, meaning their power consumption is different. Thus it isn’t easy to give a specific size generator for all. However, you can size yours by taking both appliances’ starting and running watts and adding them up to get the required wattage.

Understanding your refrigerant’s and freezer’s power ratings is the first step of sizing a generator ideal for running these two appliances. If the wattage isn’t provided, some calculations might be involved, something you can expect in such appliances. But, don’t worry – they are simple, and I will take you through them.

How to Size a Generator to Run Your Refrigerator and Freezer

We buy refrigerators and freezers to keep our foods cooked and raw fresh for longer and drinks fresh and cold. That’s why we count them as essential appliances during an outage or unstable power supply.

These two appliances are built and work differently, and their wattages are different, and the difference gets significant with various brands. That means there is no single generator that can run them sufficiently.

So, where do you start sizing a generator enough to run your refrigerator and freezer?

The starting point is understanding the appliances’ starting and running. The starting wattage is higher than the running wattages, and for justifiable reasons. That’s why you must understand the appliances power ratings before even buying your generator.

What do these ratings mean?

  • Starting/surge wattage: It’s the amount of power an appliance needs to start. It’s typically required by motor-driven appliances and those with a compressor needing a higher wattage rating to start its motor.
  • Running/rated wattage: this is the amount of power required to run the appliance after a complete startup continuously.

But since I doubt you will be hooking up the appliances to the generator alone. So, it’d be best to get a generator providing more wattage than what the freezer and the refrigerator need and 20% more than everything required.

It’d be best to have the appliances’ manual with you since you will need to check some power readings and identify the type of refrigerator and freezer. The units might look the same, but their power requirements are different.

Refrigerator and Freezer Generator Size Calculator

(Refrigerator starting watts + freezer starting watts) x (120/100) = Generator Starting Watts
(Refrigerator running watts + freezer running watts) x (120/100) = Generator Starting Watts

What is the Ideal Size Generator to Run a Refrigerator?

Among the many areas refrigerators differ is the wattage rating, both starting and running wattages. Typically, the appliance will have a sticker or plate with the wattage ratings written on it. If not available, you can find it in the manual.

The running wattage will always be lower than the starting wattage, and it’s this power rating that you need to be keen on.

With most refrigerators rated from 400 to 2000 starting watts, a generator delivering the exact wattage can start and keep it running.

For example, suppose you have a refrigerator rated 1000 starting watts; a generator rated 1000 watts can start and run the unit. However, it’d initially strain the generator engine, something you want to avoid considering the straining causes accelerated wear and tear.

Pro Tip: It’d be best to get a generator that delivers 20% more power than your appliances need to remove the strain. You’d need a unit providing 120/100*1000 = 1200 starting watts from the example above.

Energy Star® rated refrigerators are low power consumers by far. Typically, the starting wattage of these units will be in this range, but the running watts are considerably low, around 1/3 of the starting watts.

That means if your Energy Star® rated refrigerator’s starting wattage is 1000 watts, its running watts would be around 1000/3 = 334 watts (estimate).

What is the Ideal Size Generator to Run a Freezer

A freezer works in the same principles as a refrigerator. Many aspects I’ve discussed above will also apply when sizing a generator for your freezer, including the running and starting wattage ratings.

However, unlike refrigerators, freezers go beyond fridge preservation to freezing everything up. That means the compressor require more power to start and run, more than what a refrigerator needs.

Depending on the unit’s size and age, freezer starting wattage ratings range from 600 watts to 2500 watts or more.

Similar to refrigerators, a generator delivering the freezer’s rated starting wattage can start and run it. But as I tipped you above, it’d be best to get a generator producing 20% more than the rated wattage. The extra wattage can allow you even to connect some devices when the freezer starts.

What Size Generator to Run Refrigerator and Freezer

Typically, calculating the amount of power you need from a generator will require adding the individual appliances’ wattage ratings. And in this, add your fridge and freezer’s starting and running wattage ratings to know the correct size generator.

So, suppose your refrigerator starting wattage is 1000 watts, and the freezers is 1200 watts, with their running watts being 350 watts and 600 watts, respectively. That means you need a generator that delivers at least 2200 starting watts and 950 running watts.

And as I mentioned, it’s always crucial you increase the number by 20% to remove the strain these appliances insert into the engine when starting. In the example above, you need a generator delivering:

  • (120/100) x 2200 = 2640 starting watts
  • (120/100) x 950 = 1140 starting watts

It’s crucial that you get a generator delivering enough wattage required by these two appliances. Using a smaller generator would mean overloading it can damage it, leading to overheating the appliances’ motors and likely burning them out.

How to Find Refrigerator and Freezer Wattage Ratings If Not Available

If the freezer or the refrigerator wattage ratings aren’t available and you don’t have a manual, you will have to do some calculations to determine it.

Typically, the information will be on a sticker at the back, but at times, the information might be missing and what you get are the amperage and the voltage. But don’t worry, the calculations are simple, and I will also include a calculator to simplify things even better.

Take the amps and voltage readings, multiply them and get the rated watts.
Rated amps x rated voltage = rated wattage

With the rated watts, you can estimate the starting wattage by tripling the wattage to be on the safer side.
Rated watts x 3 = starting watts

Pro tip: you can start your generator, hook up the refrigerator, allow it to start and then hook up the freezer. That way, you can use a generator delivering with lower starting watts but with enough wattage to run both units.

Related Questions

Is it safe to run a refrigerator on a generator?

Yes, it’s safe so long as you’re using the right generator. Overloading the generator might not be that safe; it can cause damages to both your generator and the appliances.

Can a power station run a refrigerator and a freezer?

Yes, it can. However, the power station has to deliver enough power to run both the appliances. There is a trick though, you could start one appliance, minus the appliance running watts from the power station surge wattage and see if it’s more than the next appliance’s starting watts. Remember, the power station might run your fridge and freezer, but it might not run it for too long. Power stations aren’t like generators; they might be unreliable, especially with their power hour rates.

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Sharif Gen

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