Sizing and cost calculators

What size generator to run refrigerator and freezer

Closed refrigerator and freezer in a bright kitchen.

The short answer

What size generator to run refrigerator and freezer? Size from your own exact data. Add all running watts that can happen at once. Then add the largest single starting gap if only one motor can start at a time. Add every gap if motors can start together. Compare the result with a model's published running and maximum figures for your fuel and voltage. Those figures are a screen, not a full fit test.

Last updated October 2026

What's covered11

A refrigerator and a freezer can share one generator. The size depends on two kinds of load. One is the steady running load. The other is the short burst a compressor needs to start.

This page shows the math for both. It also explains why the load rises and falls. The aim is a number you can check against a model's published figures.

Add the running watts of everything that can run at the same time. If only one motor can start at a time, add the largest single starting gap. If motors can start together, add every starting gap. A gap is one unit's starting watts minus its own running watts. Then compare the total with exact generator figures for your fuel.

Two ways to size a generator for a refrigerator and freezer

The table below compares the two start cases. R means all running watts that can be on at once. A gap means one unit's total starting watts minus its own running watts. A negative gap counts as zero.

Start case Formula When to use it Main risk
One unit starts at a time S = R + largest single gap You have exact data and a reason to expect one start at a time Two starts may still overlap
Units can start together S = R + sum of all gaps Starts can overlap, or you cannot rule it out Needs a larger starting figure
Running check only Compare R alone Never as a final answer Ignores the start burst

Notice that R already holds every running load. So you add only the extra gap, not the full starting value. Adding the full starting value to R would count the same motor twice. Leaving a motor out of R and adding only its gap would undercount.

Running watts and starting watts explained

Running watts are the power an appliance draws while it works. A generator must carry that load for as long as the appliance runs. Starting watts are the higher total a motor needs for a moment as it starts.

The starting figure on a data sheet is a total. It already includes the running part. That is why the gap is the useful number. The gap is the extra power above running that a start asks for.

Some data plates list volts and amps instead of watts. Volts times amps gives volt-amps, not watts. The US Department of Energy style guide notes that this is apparent power unless the power factor is known. So you cannot turn volt-amps into watts without that factor.

Use the maker's own wattage data when it exists.

The running wattage vs starting wattage page covers this split in more depth. It helps if a spec sheet shows several figures and you are unsure which one applies.

Cycling versus surge

Cycling and surge are two separate ideas. Cycling is the on and off pattern of a compressor. Surge is the brief extra draw at each start.

A thermostat turns each compressor on and off. So the load is not one fixed number over the day. At some moments neither compressor runs. At others one runs, or both run.

Each time a compressor cycles on, it starts again. That means the starting gap can return many times during an outage. A generator must handle the start every time, not just once.

Cycling is why the start case matters. Two thermostats work on their own. You cannot assume their starts will never line up. If you lack a reason to rule out overlap, use the simultaneous formula.

Other items count too. Anything else on the generator adds to R. A light or a charger running while a compressor starts is part of the load.

How to combine the loads step by step

First, list every item that could run at the same time. For each, write its running watts and its total starting watts. Use exact numbers from the appliance maker.

Second, add all the running watts together. That sum is R. Include items without motors, since they draw running power too.

Third, find the gap for each motor. Subtract its running watts from its own starting total. If the answer is below zero, use zero.

Fourth, pick the start case. For one start at a time, add only the largest gap to R. For starts that can overlap, add every gap to R. If you have more than one of the same unit, multiply that gap by the count.

Here is an illustrative example using letters only. Say the refrigerator runs at Rf and starts at Sf total. Say the freezer runs at Rz and starts at Sz total. Then R equals Rf plus Rz.

The refrigerator gap is Sf minus Rf. The freezer gap is Sz minus Rz.

Now a number. Honda's US guide estimates an Energy Star refrigerator at 132 to 192 W running and 1,200 W starting. Take 192 W. The gap is 1,200 minus 192 = 1,008 W. On its own, R = 192 W and S = 192 + 1,008 = 1,200 W. A freezer would add its own running watts and gap from its nameplate. These are estimates, not measurements of your appliance.

For one start at a time, S equals R plus the larger of the two gaps. For starts together, S equals R plus both gaps. In both cases, R stays the same. Only the start allowance changes.

The generator size calculator runs this math with your own figures. It is a good next step once you have both data plates.

Comparing your total with a generator

After you have R and S, look at a generator's published figures. Its running or rated figure should cover R. Its maximum, peak or starting figure should cover S.

Check the figure for the fuel you plan to use. On some listed models, the numbers change by fuel. For example, the Westinghouse iGen2550DFc lists 1900 W running and 2550 W peak on gasoline. On propane it lists 1700 W running and 2300 W peak.

The Champion 201278 lists 3500 W running on gasoline and 3150 W on propane. Its starting figure is 4500 W on both fuels. The Champion 201176 runs on gasoline, propane and natural gas. It lists 7250 W, 6525 W and 5875 W running on those fuels.

These differences apply to these listed models only. Do not assume the same pattern for every model. Read the exact table for the model you are checking.

The Honda EU2200i lists 1800 W rated and 2200 W maximum at 120 V. The Honda EU3200i lists 2600 W rated and 3200 W maximum at 120 V. Both run on gasoline.

A published figure is a screen. It does not prove a model will start a given compressor. You still need the appliance's running watts, total starting watts, voltage and plug type. You also need to know how long you must run it.

Voltage and connection checks

Voltage is its own check. Read the voltage on each appliance's data plate. Then confirm the generator offers that voltage. The Honda models above list 120 V.

The Champion 201176 lists 120/240 V.

An adapter cannot create a voltage the generator does not make. Generac's home connection guidance states this clearly. A 120 V output does not rule out every transfer system. But the generator, switch, inlet, panel and circuits must all match.

An RV outlet does not prove a model is approved for home transfer use. Westinghouse states that the iGen2550DFc has a TT-30R outlet and is not transfer-switch-ready. Use the maker's own wording for any model you check.

Manual transfer gear keeps utility power and generator power apart. Installation and service belong to licensed electricians. They follow the product instructions and local code. Do not change wiring, the neutral or any gas line yourself.

Do not bypass any protection device.

Fuel-burning generator placement

Engine generators make carbon monoxide. The CPSC carbon monoxide guidance sets clear rules for portable units. Run them outdoors at least 20 feet from the home. Point the exhaust away.

Never run one indoors or in a garage, even with the doors open.

The CPSC portable generator safety alert adds more steps. Use a dry surface and follow the maker's rules for wet weather. Do not touch the unit with wet hands. Shut it off and let it cool before you refuel.

Never plug it into a wall outlet to feed the house. Use CO alarms, and get to fresh air if one sounds or you feel symptoms.

A standby generator follows its own manual and local rules for clearance. The 20-foot figure is for portable units. Even an automated engine generator still needs safe outdoor placement.

Battery power stations for this load

A battery power station stores energy instead of burning fuel. It has two limits that matter here. One is its AC output in watts. The other is its stored energy in watt-hours.

Watts are power. Watt-hours are stored energy. Watts times hours gives watt-hours. So the output figure is compared with R and S.

The watt-hour figure limits how long it can carry the load.

The BLUETTI AC200L lists 2048 Wh of capacity and 2400 W rated AC output. It has 120 V US outlets and recharges from solar or AC. The Jackery Explorer 2000 v2 lists 2042 Wh and 2200 W rated AC output. It also has 120 V US outlets.

The same maker pages list 3600 W surge for AC200L and 4400 W surge for Explorer 2000 v2. Compare R with rated output and S with the declared surge.

The cited specs do not give surge duration or a runtime for your exact fridge and freezer. A wattage match alone does not prove that both compressors can start. Confirm the allowed surge time and each appliance's start demand. Follow each maker's placement and use instructions.

Sources, method and limits

Model figures come from the makers' own US product pages. Safety rules come from the CPSC. Unit rules come from the US Department of Energy style guide.

We used the published running, rated, peak and maximum figures as listed. We did not measure any generator. We did not test any refrigerator or freezer. No noise, runtime or start test was run for this page.

Apart from Honda's labeled estimate in the example, this page gives no typical appliance wattage. Real appliances vary, so only your own data plate counts. It gives no price or fuel storage time. It makes no claim about medical device backup.

The method has limits. It assumes your starting figures are exact. It does not cover fuel pressure, gas flow or site setup. Those are separate checks for a licensed trade.

A product's output is also not a full fit result. Voltage, plug type and duration still need checking.

For wider sizing beyond cold storage, see what size generator do I need. It covers more types of home loads.

What size generator to run refrigerator and freezer FAQs

Do I add both full starting watts together?

No. Add both running watts into R first. Then add only the gaps, which are starting watts minus running watts for each unit. If both compressors can start at once, add both gaps.

If only one can start at a time, add the largest gap. Never add full starting values on top of R.

Does staggering the starts let me use a smaller generator?

It can lower the start allowance if only one motor truly starts at a time. It does not lower R, since both units still draw running power once on. Thermostats cycle on their own, so later starts can still overlap. If you cannot rule overlap out, size for both gaps together.

Can I use volts times amps from the data plate?

Volts times amps gives volt-amps, not watts. You need the power factor to turn volt-amps into watts. Without it, the figure is not a true watt value. Look for a wattage figure from the appliance maker.

Use those exact running and starting numbers in your math.

Does fuel type change the generator size I need?

Fuel does not change what your appliances draw. It can change what a listed model delivers. The Champion 201176, Champion 201278 and Westinghouse iGen2550DFc all list lower running watts on some fuels than on gasoline. Check the exact table for your fuel.

Do not assume this applies to every model.

Primary documents

What size generator to run refrigerator and freezer Verdict

What size generator to run refrigerator and freezer? Start with exact data from both appliances. Add every running load that can be on at once to get R. Then choose your start case.

Add the largest gap for one start at a time, or every gap if starts can overlap.

Compare R with the model's running figure for your fuel. Compare S with its maximum or starting figure. Then check voltage, plug type and how long you need power. If any of those fail, the model is not a fit, whatever its output says.

Continue your backup plan

Choose your next step

Once you have a size, read the generator sizing guide and follow its link to the home generator picks. Match the exact fuel, voltage and starting limits to your result before you choose.