How many watts does a freezer use?
A standalone freezer uses 100 to 350 watts while running, with a typical mid-size chest or upright settling around 150 watts when the compressor is on. A small 5 cubic foot chest freezer runs closer to 55 to 100 watts, while a large 20 cubic foot upright can hit 300 watts or more. As with a refrigerator, that is far below the nameplate rating, which often reads 5 to 7 amps (roughly 600 to 840 watts at 120 volts). The nameplate is a rated maximum, not the minute-to-minute draw, so do not size your power off it.
A freezer runs on a standard 120-volt household outlet and does not need a 240-volt circuit the way a dryer or water heater does. A dedicated circuit is still smart so the compressor is not sharing a breaker with other loads, but the appliance itself is an ordinary plug-in. For the honest number for your exact unit, read the yellow EnergyGuide label for its estimated annual kWh, which already accounts for the compressor cycling on and off rather than running flat out.
Does a freezer use more electricity than a fridge?
No, usually a standalone freezer uses about the same or slightly less electricity than a full refrigerator, and a chest freezer is often the most efficient of the two. A modern chest freezer uses roughly 0.5 to 1.5 kWh a day, while a full refrigerator uses about 1 to 2 kWh. The freezer wins because it is better insulated, it is usually manual-defrost (no electric defrost heater), and its single compartment holds one steady temperature.
The type matters more than the brand. A chest freezer is the efficiency champion: cold air sinks, so very little escapes when you lift the lid, and most models have no frost-free heater. An upright freezer is more convenient to load but uses more power, because a frost-free (auto-defrost) model runs a heater on a timer to melt frost, and cold air spills out the door every time you open it. If the lowest running cost is the goal, a manual-defrost chest freezer beats an auto-defrost upright, often by 100 to 200 kWh a year.
How much electricity does a freezer use per day, month, and year?
A standalone freezer uses about 1 to 2 kWh per day (a chest freezer often 0.5 to 1.5), which works out to roughly 30 to 60 kWh a month and 200 to 600 kWh a year. Energy Star chest freezers sit near the bottom, around 215 kWh a year, while large frost-free uprights land at the top. At the US average rate near 17 cents per kWh, that is roughly $3 to $10 a month to run, or about $40 to $120 a year. These are estimates; your actual cost depends on your rate, how full the freezer is, and where it sits (a hot garage makes the compressor work harder).
Day-to-day use is lower than the running wattage suggests because the compressor only runs about a third of the time, cycling on and off to hold temperature. A freezer that pulls 150 watts while running averages only about 35 to 80 watts around the clock. That averaged figure, not the running wattage, is what your solar panels or battery actually have to replace, so it is the number to size a system around. For the difference between power and stored energy, see watts to kWh and kW vs kWh.
Why is a full freezer cheaper to run than an empty one?
A full freezer is cheaper to run because frozen food is thermal mass: it stays cold on its own and helps hold the temperature steady, so the compressor cycles on less often than it would in a freezer full of nothing but air. Every time you open an empty freezer, cold air falls out and warm air rushes in, and the compressor has to re-chill that air from scratch. A packed freezer barely notices the door opening.
The classic trick is to fill empty space with jugs of water or sealed containers, which freeze into blocks of ice and act as ballast. They keep the freezer running efficiently when it is not full of food, and, more importantly, they become your backup cold source. The running-cost savings from a full freezer are modest (a few dollars a year), so do not overfill it to the point that air cannot circulate. The real payoff shows up the moment the power goes out.
How long will a freezer stay cold in a power outage?
A full freezer keeps food frozen for about 48 hours after the power goes out if you keep the door closed, and about 24 hours if it is only half full, according to USDA guidance. A chest freezer tends to hold longer than an upright because less cold air escapes. This is the freezer's superpower: unlike a refrigerator, which only holds safe temperatures for about 4 hours unpowered, a freezer can coast through a one or two day outage on its own thermal mass with no power at all.
That changes how you back one up. You often do not need to run a generator or battery continuously; you only need to top the freezer back up before it drifts above frozen. Keep the lid shut, add those frozen water jugs for extra mass, and the freezer buys you a long runway. If an outage stretches past two days, run a generator or plug the freezer into a battery for a few hours to re-freeze, then let it coast again. That intermittent duty is far gentler on your fuel or battery than running a load around the clock.
What size generator, inverter, or solar does it take to run a freezer?
A freezer needs a pure sine wave inverter or generator rated for its running watts with enough surge headroom for the startup spike, which in practice means a 1,000 to 2,000 watt source for a typical unit. The startup surge is the gotcha: the compressor is a motor, and it briefly pulls 600 to 1,200 watts (two to three times its running load) the instant it kicks on. An inverter or generator that matches the 150-watt running draw but cannot deliver the surge will trip every cycle, so size by the surge, not the running number, and use pure sine power to keep the compressor from running hot.
For solar, the freezer is a friendly load precisely because it can coast. You can let panels charge a battery during the day and run the freezer off that battery, or run it intermittently and lean on its thermal mass between charges. A portable power station around 1 kWh keeps a freezer cold for roughly 12 to 20 hours on its own, and a solar panel to recharge it stretches that across a multi-day outage. Add the freezer's daily kWh to your other loads and run it through the solar panel calculator for a panel count in your climate; our breakdown of what a 100Ah battery can run shows how long stored power lasts a load this size. Whole-house backup that picks the freezer up automatically needs a home battery and a backup-capable inverter, which is wiring for a licensed electrician; a plug-in solar generator is the setup you can do yourself.
Frequently asked questions
Will a 2000 watt generator run a freezer?
Yes, comfortably. A freezer draws about 150 watts while running and surges to roughly 600 to 1,200 watts on startup, so a 2,000-watt generator runs it with plenty of room to spare, usually enough left over for a few lights or a phone charger. A quiet 2,000-watt inverter generator is a common choice for keeping a freezer going during an outage. Just confirm the rating is 2,000 watts continuous, not a 2,000-watt peak with a lower running figure.
Will a 5000 watt generator run a fridge and freezer?
Yes, easily. A refrigerator and a standalone freezer together need only about 300 running watts, with brief startup surges that a 5,000-watt generator handles without strain. A unit that size runs both appliances plus several other loads (lights, a well pump, a furnace blower) at the same time. The only thing to watch is two compressors surging at the exact same instant, which a 5,000-watt generator still has ample headroom to cover.
Will a 1200 watt generator run a freezer?
Usually yes, for the freezer alone. A freezer's 150-watt running load is tiny for a 1,200-watt generator; the question is whether the generator's surge rating covers the compressor's 600 to 1,200 watt startup spike. Most 1,200-watt inverter generators have a surge rating above that, so they start and run a single freezer fine. Running a freezer and a refrigerator together on 1,200 watts is risky, because both compressors can surge at once and trip it.
How many watts does a chest freezer use?
A chest freezer uses about 55 to 100 watts running for a small 5 cubic foot model and roughly 100 to 200 watts for a mid-to-large one, averaging only 35 to 80 watts around the clock once you account for the compressor cycling. Over a day that is about 0.5 to 1.5 kWh. Chest freezers are the most efficient type because cold air sinks and stays inside when you open the lid, and most are manual-defrost with no electric heater.
How long will a freezer keep food frozen without power?
A full freezer keeps food frozen for about 48 hours after a power outage if you keep the door closed, and about 24 hours if it is half full, per USDA guidance. Packing it with frozen water jugs or ice packs adds thermal mass and extends that window. If the power stays out longer, food that still has ice crystals or is at or below 40 degrees Fahrenheit is generally safe to refreeze or cook.