How Many Watts Does a Refrigerator Use?

The short answer, and the three numbers behind it

A full-size refrigerator, 18 to 22 cubic feet, draws 150 running watts, surges to 750 watts as the compressor starts, and averages about 55 watts over a day. That average is 1.31 kWh in 24 hours.

Three numbers, three different jobs:

• Running watts, 150 W. What the compressor pulls while it is working. This is the figure you add to everything else when you are checking whether a generator or an inverter can carry the load.
• Starting watts, 750 W. The fraction of a second when the compressor motor breaks free against system pressure. It is five times the running figure, and it is what actually trips small inverters.
• Average watts, 55 W. The running figure weighted by how much of the hour the compressor is on, roughly 35 percent in a warm room, plus a couple of watts of standby for the controls and the light. This is the number that empties a battery or a fuel tank.

Mixing these up is expensive in both directions. Size on the nameplate and you buy twice the generator you need. Size on the average and the fridge shuts your power station down the first time it cycles on. The Watts I Need calculator keeps the three separate for whatever list you give it.

What refrigeration and cooling gear actually draws

Read the starting column against the running column. A box fan has no gap at all, because there is nothing to break free. Every compressor has a gap of several hundred watts, and window air conditioners have gaps in the thousands. That gap, not the running total, decides whether a power source can start the appliance at all. There is a fuller explanation of the split in our guide to starting watts vs running watts.

Why the nameplate is not what it averages

A refrigerator is a thermostat with a motor attached. It cools to setpoint, shuts off, warms a degree or two, and cools again. In a normal room it spends about a third of each hour with the compressor on. That is where 150 W of running draw becomes 55 W of average draw, and 3.6 kWh of nameplate arithmetic becomes 1.31 kWh of real energy.

The duty fraction is a rule of thumb, not a guarantee. It climbs in a hot garage, in humid weather, when the door gets opened every few minutes, and when the coils behind the unit are furred with dust. It drops in a cool basement. If your fridge lives somewhere hot, push the duty figure up in the calculator and watch the battery requirement rise with it.

Will a 1,000 W power station run a fridge?

Yes, comfortably, and here is every class side by side. These are computed from the same engine the calculator uses, with the standard 85 percent inverter efficiency applied.

Two rows deserve a comment. The 300 Wh class holds enough energy for four and a half hours of fridge, but its surge ceiling is 600 W and the compressor asks for 750 W, so it never gets past the first start. Capacity was never the problem. At the other end, the 1,000 to 1,150 Wh class gives you roughly 870 Wh of usable energy and about 16 hours of fridge, which covers an evening outage and most of a night.

To cover a genuine 24 hour day, the sizing maths asks for about 1,800 Wh of battery, once inverter losses and a small reserve are included. That is the 2,000 Wh class. Below freezing, expect a further 15 percent penalty on top, so a cold garage costs you a couple of hours.

What size generator for a refrigerator

Using the site's sizing rule, running watts times 1.25 for continuous headroom, plus the single largest surge on top, a lone refrigerator needs 190 W of continuous capacity and 750 W of starting capability. Even the smallest class on our list, the 1,000 W inverter at 900 W continuous and 1,000 W starting, clears that. The starting margin is only 250 W, though, which is thinner than it looks on an old compressor.

The 2,200 W inverter class is what most people actually buy, and the reason is everything else on the list. Add a chest freezer, ten LED bulbs and the router, and you get 380 W running, 980 W starting and 3.30 kWh across a day. A 2,200 W inverter runs that group for about 15 hours 25 minutes on its 0.95 gallon tank.

Run the fridge alone on that generator and the tank lasts roughly 22 hours, but most of the fuel goes into spinning the engine rather than into the food. A generator carrying 55 W is burning fuel to idle. Either give it more work to do or run it in blocks, which is the next section. If you are weighing the engine against a battery at all, our generator vs portable power station comparison covers where each one wins.

A fridge is the cheapest thing on the outage list

Take the standard home backup list: refrigerator, chest freezer, furnace blower, sump pump, lights, TV, internet and two phones. That comes to 2,100 W running, 3,700 W starting, and 16.1 kWh over a full day. The refrigerator is 1.31 kWh of that, about 8 percent.

The starting figure is set by the sump pump, not the fridge. The energy is dominated by the furnace blower. Keeping the food cold is close to a rounding error in both columns, which is worth remembering when someone tells you that saving a freezer full of meat requires a whole-house generator. It requires a small one, run sensibly.

Run the generator in blocks, not all day

Because the compressor needs only about a third of an hour, a fridge spends most of its life coasting on cold it has already banked in the food. That is what makes intermittent running work: power the fridge for a stretch, let it pull the box back down to temperature, then shut the generator off and let the mass hold.

Two things decide how long a block lasts you. A full fridge holds temperature far better than an empty one, so fill the gaps with jugs of water before the storm rather than after. And every door opening throws away part of what you just paid for, so decide what you want before you open it. Follow your local food safety guidance on how long food stays safe without power, and use a thermometer inside the box rather than guessing.

Mini fridges, chest freezers and commercial prep tables

A mini fridge at 3 to 5 cubic feet draws 80 W running and 320 W starting, averaging 30 W, or about 700 Wh a day. Its surge is small enough that even a 300 Wh station starts it, and runs it for around 8 hours 40 minutes. This is the one refrigeration load a small battery genuinely handles.

A chest freezer draws 120 W running and 600 W starting, averaging 40 W, or roughly 910 Wh a day. Note that 600 W is exactly the 300 Wh class surge ceiling, which is a coincidence rather than a margin. Step up to the 700 to 800 Wh class and you get about 17 hours. A chest freezer also tolerates intermittent power better than a fridge, because a sealed, packed freezer has far more stored cold to spend.

Commercial refrigeration is a different animal, mostly because the lid never stays shut during service:

A refrigerated prep table averages 160 W against a home fridge's 55 W, and it is not because the box is bigger. It is because the duty fraction runs near 40 percent when a line cook is in and out of it all service. Put a prep table and an undercounter fridge together and you are at 750 W running, 1,950 W starting and 2.45 kWh across an eight hour service: a 2,200 W inverter generator, or a 3,600 Wh battery if the site will not take an engine.

Whatever your combination, put your own list into the calculator and it will give you the running total, the one surge that matters, and the runtime on every generator and battery class on the page.