How long will a power station run a chest freezer?

Average watts set the runtime

A chest freezer does not draw its compressor's running wattage continuously. The compressor cycles on and off, so average power consumption is more useful for estimating battery runtime.

Across 50 ENERGY STAR certified chest freezers in our dataset, the median annual energy use is 211 kWh. That works out to approximately 24 W averaged across the year. Full-size upright freezers average about 50 W at the median, a difference that matters when choosing a portable power station for a long outage.

Battery capacity is measured in watt-hours (Wh) and appliance demand in watts (W). For runtime planning, divide the battery energy that reaches the appliance by the appliance's average watts. Our calculation assumes 80% to 90% of rated battery capacity reaches AC appliances, which accounts for the gap between stored energy and the energy available to the load. See watts vs watt-hours for the distinction.

Average consumption sets the energy estimate. Compressor startup still needs to fall within the station's capabilities.

Find your freezer's average from its EnergyGuide label

Your freezer's EnergyGuide annual kWh figure gives a more useful estimate than applying the same 24 W average to every model. Use this formula:

Average watts = annual kWh x 1,000 / 8,760

The median ENERGY STAR chest freezer uses 211 kWh per year: 211 x 1,000 / 8,760 = 24.1 W, which we round to 24 W. The median full-size upright freezer uses 435 kWh per year: 435 x 1,000 / 8,760 = 49.7 W, which we round to 50 W.

Find your freezer's annual energy consumption on its EnergyGuide label, calculate its average watts and enter that number into our runtime calculator.

These are annual averages, not guarantees for every outage. They cannot establish actual runtime for an older freezer, one that is opened often or one sitting in a hot garage. Use your own freezer's figures rather than assuming it matches the dataset median.

Chest vs upright freezer

Chest and upright freezers have different average energy demands in the ENERGY STAR data collected on October 9, 2026.

The chest freezer dataset covers 50 certified models from 2.5 to 21.7 cubic feet. Annual consumption at the 10th to 90th percentile ranges from 173 to 226 kWh, or approximately 19.7 to 25.8 W. The full dataset spans 15.6 to 39.5 W.

The upright dataset covers 350 full-size freestanding models from 8.3 to 23 cubic feet. Its 10th to 90th percentile is 354 to 493 kWh a year, or approximately 40 to 56 W. The full range is 28 to 62 W. Upright auto-defrost models use roughly twice the energy of chest freezers.

The estimated compressor running demand also differs:

• Chest freezer: 59 to 118 W while running.
• Upright freezer: 121 to 169 W while running.

These running ranges are derived from a refrigerator duty-cycle rule, and the chest freezer range is checked against freezer compressor data. They are not measurements of every model, and the upright estimate leaves out the defrost-heater cycle, which is not sourced. For battery sizing, start with average energy consumption, then check running and startup requirements separately.

Worked examples

These figures are our calculation, assuming 80% to 90% of rated capacity reaches AC appliances. Each example uses a chest freezer averaging 24 W unless stated otherwise.

• Jackery Explorer 300, 293.8 Wh: 9.8 to 11.0 hours. Its 300 W continuous output and 500 W surge rating do not by themselves establish compatibility with every freezer compressor.
• Anker SOLIX C1000 Gen 2, 1,024 Wh: 34.1 to 38.4 hours. The energy reaching the freezer is 1,024 x 0.80 = 819.2 Wh to 1,024 x 0.90 = 921.6 Wh, and 819.2 / 24 = 34.1 hours while 921.6 / 24 = 38.4 hours.
• Jackery Explorer 2000 v2, 2,042 Wh: 68.1 to 76.6 hours for the chest freezer, or 32.7 to 36.8 hours for a full-size upright averaging 50 W.
• EcoFlow DELTA Pro 3, 4,096 Wh: 136.5 to 153.6 hours for the chest freezer, or 65.5 to 73.7 hours for the upright.

These estimates describe energy availability for the stated averages. They do not establish compressor startup compatibility or predict consumption under every operating condition.

Start-up power

A freezer compressor can demand substantially more power when starting than while running. For small 115 V freezer compressors rated from 1/12 to 1/8 hp, Danfoss datasheet figures indicate locked-rotor demand of approximately 449 to 833 VA.

VA is not the same as watts. The figures describe apparent power at startup, so they cannot be compared directly with a station's surge rating in watts to declare a guaranteed match. Larger chest freezers may use larger compressors, and startup demand for full-size upright freezers is not sourced.

That means we cannot give a minimum surge wattage that is sure to start every chest or upright freezer. Before choosing a station, check the freezer maker's compressor starting requirements; running watts alone are not enough to confirm that startup will succeed.

Running a fridge and a freezer together

Our refrigerator reference averages 60 W. Combined with a 24 W chest freezer, that makes an 84 W average load. Replace the chest freezer with a full-size upright averaging 50 W, and the combined load becomes 110 W. Our calculation gives these examples:

• 1,024 Wh Anker SOLIX C1000 Gen 2: 9.8 to 11.0 hours for the fridge and chest freezer, or 7.4 to 8.4 hours for the fridge and upright.
• 2,042 Wh Jackery Explorer 2000 v2: 19.4 to 21.9 hours for the fridge and chest freezer, or 14.9 to 16.7 hours for the fridge and upright.
• 3,584 Wh Jackery HomePower 3600 Plus: 34.1 to 38.4 hours for the fridge and chest freezer, or 26.1 to 29.3 hours for the fridge and upright.

All estimates assume 80% to 90% of rated capacity reaches AC appliances. Both compressors have startup requirements, and these runtime calculations do not establish that either appliance will start. The refrigerator runtime guide covers the refrigerator side in more detail.

How long food stays safe without power

A portable power station can help keep a freezer running, but food safety still depends on temperature. According to FoodSafety.gov:

• A full freezer holds its temperature for about 48 hours if its door remains closed.
• A half-full freezer holds its temperature for about 24 hours with the door closed.
• Keep the freezer at or below 0°F and the refrigerator at or below 40°F.
• Discard perishable food that has been above 40°F for 2 hours or more.

An unopened refrigerator keeps food cold for about 4 hours without power. These are food safety guidelines, not power station runtime estimates, and a battery's calculated operating time does not guarantee that a particular freezer stays at the required temperature. Keeping the door closed matters whether the freezer runs from a power station or waits for the grid to return.

Choosing a size

For a chest freezer near the 24 W ENERGY STAR median, a 1,024 Wh station provides 34.1 to 38.4 hours in our calculation. The same battery gives a 50 W upright freezer 16.4 to 18.4 hours, less than half as long. A 2,042 Wh station extends the chest freezer figure to 68.1 to 76.6 hours, and a 4,096 Wh station to 136.5 to 153.6 hours.

For a refrigerator and freezer together, size the battery from their combined average load rather than the freezer alone. Capacity is only part of the decision: the station must also support the appliances' running power and compressor startup, which these generic figures cannot guarantee.

Start with your EnergyGuide annual kWh rating, enter your loads in the runtime calculator and use the size calculator to plan capacity. For longer outages and several essential loads, see the home backup guide.