Guide

How Long Will a Power Station Run a Refrigerator

Estimate refrigerator runtime from annual kWh, average watts, surge versus running watts, and a simple watt-hour formula — using ENERGY STAR, EIA, and manufacturer figures, not invented tests.

Published 10 November 2026 · Updated 10 November 2026 · Worked estimates from official energy-use data. We have not timed a fridge on a power station in a lab.

A refrigerator is usually the first appliance people want on a portable power station. It is also the easiest one to mis-estimate, because the number on a marketing “runtime” table, the number on the nameplate, and the number that actually drains the battery are often three different things.

This walk-through uses a public formula, the official ENERGY STAR certified-model dataset, and the US Energy Information Administration’s Residential Energy Consumption Survey. It is not a lab test of any fridge or any power station, and it does not use prices or star ratings.

The three wattages that get mixed up

Starting (surge) watts are the short spike when the compressor motor starts. Honda’s wattage estimation guide lists an ENERGY STAR refrigerator or freezer at approximately 1,200 W to start and 132–192 W to run. The starting figure is what the inverter must survive. If it cannot, the station may click off at the moment the compressor kicks in.

Running watts are the draw while the compressor is actually on. They tell you whether the station’s continuous AC output is enough. Every 1 kWh-class station cited in our 1000Wh outage guide publishes a continuous output of 1,500–1,800 W, which is well above Honda’s 132–192 W running range — so the usual bottleneck for those models is surge and energy, not continuous watts.

Average watts over hours or days set the runtime. A fridge cycles. Over a year, ENERGY STAR and EIA publish annual kilowatt-hours, which already include that cycling. Convert with:

Average watts ≈ (kWh per year ÷ 8,760 hours) × 1,000

8,760 is the number of hours in a non-leap year, the usual conversion.

Two official pictures of “a refrigerator”

New certified models and the stock of machines actually in homes are not the same.

New ENERGY STAR certified models

We queried the official ENERGY STAR Certified Residential Refrigerators dataset on 10 November 2026 (4,930 certified models). Annual energy use is the tested figure EPA publishes for each model.

The 17–19 cu ft top-freezer group has a median capacity of 18.1 cubic feet. That is consistent with the US Department of Energy’s Federal Energy Management Program example, which cites 363.5 kWh/year for an ENERGY STAR 18.1 cu ft top-freezer with automatic defrost (guidance updated December 2023).

These medians are for certified models on the market, not a census of what people already own. Older refrigerators can use substantially more; ENERGY STAR certification is a threshold, not a description of the installed base.

Refrigerators actually in US homes (EIA)

The EIA’s 2020 Residential Energy Consumption Survey, Table CE5.3b (revised March 2024), estimates average site electricity use per household that has the end use:

The “all refrigerators” row is a household total, not a single appliance, so do not put 839 kWh into the runtime formula unless you really are backing up every fridge at once.

EIA also notes, in its explainer on electricity use in homes, that 99% of US homes had a refrigerator in 2020 and 34% had two or more. The most-used refrigerator cost about $87 to run that year; we use the kWh figure from Table CE5.3b rather than converting that dollar amount back, because the table is the direct quantity.

The gap between ~41–52 W (new ENERGY STAR examples) and ~70 W (typical most-used fridge in 2020) is the main reason two honest estimates can differ by a third. If you know your model’s EnergyGuide kWh, use that. If you do not, the EIA 70 W average is the more conservative planning number for an unknown machine already in the kitchen.

Put the numbers through the formula

Runtime (hours) ≈ battery capacity (Wh) × 0.85 ÷ average watts

The 0.85 factor is a planning assumption for inverter and conversion losses. BLUETTI publishes 85% inverter efficiency for the AC180, and also applies a 90% depth of discharge and about 15 W of self-consumption. If you want to be stricter than the simple formula, use the maker’s version.

Worked examples, using the simple formula:

Hours are rounded to the nearest hour except the “compressor held on” row, which shows what happens if you wrongly treat running watts as a 24-hour load. In a real kitchen the compressor cycles, so the ENERGY STAR and EIA rows are the better duration estimates — provided the inverter can handle each start.

Why a 120 W “fridge” row is a different claim

Manufacturer pages often show a refrigerator runtime that looks shorter than the EIA/ENERGY STAR math. EcoFlow’s DELTA 2 US page lists a refrigerator example at 120 W and 7–14 hours. 1024 × 0.85 ÷ 120 ≈ 7.3 hours, which matches the low end of that range if they are applying a similar efficiency factor and perhaps a duty-cycle band for the high end. Anker’s SOLIX C1000 page lists a “Refrigerator, 14 hrs” example without stating the assumed watts in the same summary.

Those rows are not wrong so much as underspecified. 120 W is closer to a running-watt or high-duty-cycle assumption than to a 41–70 W average from annual kWh. When a brand does not state the load, you cannot audit the hours. Prefer a calculation you can reproduce from a kWh figure on your EnergyGuide label.

BLUETTI also notes, under its AC180 runtime FAQ, that the published formula is “NOT suitable for inductive loads with compressors, like refrigerators,” and that the blender example is for reference only. That is a fair caution: a compressor’s start-up, defrost heaters, and door openings all move the result. The formula is still the right planning tool; it is not a stopwatch.

What changes the estimate in a real outage

• Door openings and a warm kitchen. Annual kWh is measured under a standard test (DOE 10 CFR 430, Subpart B, Appendix A, as cited by FEMP). A crowded, warm apartment during a summer outage will be harder on the battery than the test condition.
• Ice makers and through-the-door dispensers. In the ENERGY STAR set, adding an ice maker is associated with higher annual kWh (the 17–19 cu ft top-freezer median moves from 363 kWh without an ice maker to 450 kWh with one). FEMP likewise advises that through-the-door ice typically uses more energy.
• A second fridge or a garage unit. EIA’s second-refrigerator average is 494 kWh/year. If both must stay up, add the average watts and size the battery for the sum — and for two starting surges, preferably not at the same moment.
• Keep the doors closed when you can. Ready.gov says a refrigerator will keep food cold for about four hours if it stays closed, and a full freezer about 48 hours. That is about food safety, not battery math, but it means you can sometimes let the fridge ride without power for a stretch.
• Do not backfeed the building. Plug the fridge into the station (or a properly rated extension cord), or use a transfer switch installed by a qualified electrician. The US Consumer Product Safety Commission warns never to power house wiring by plugging a generator into a wall outlet (“backfeeding”). The same electrical hazard applies if you try to feed a panel from a battery inverter that way.

A short method you can reuse

1. Find annual kWh on the EnergyGuide label, in the ENERGY STAR product finder, or, if the fridge is unknown, start from EIA’s 617 kWh/year most-used figure.
2. Convert to average watts: kWh ÷ 8,760 × 1,000.
3. Estimate hours: battery Wh × 0.85 ÷ average watts (or the manufacturer’s formula).
4. Check starting and running watts against the station’s surge and continuous AC ratings, and against the voltage in your country.
5. Leave margin for heat, age, and defrost cycles.

For the apartment safety constraints, see Backup power for renters and apartments. For the high-load contrast, see Can a power station run a window AC or space heater?.

Related: What can a 1000Wh power station run during an outage, and backup power for renters and apartments.

Sources

• ENERGY STAR Certified Residential Refrigerators dataset (p5st-her9), queried 10 November 2026; product finder.
• US EIA, Table CE5.3b, 2020 RECS (revised March 2024); Electricity use in homes.
• US Department of Energy FEMP, Purchasing energy-efficient residential refrigerators (18.1 cu ft top-freezer example, updated December 2023).
• Honda Power Equipment, Wattage estimation guide.
• EcoFlow DELTA 2 US product page (120 W / 7–14 hour refrigerator example; 1024 Wh).
• BLUETTI AC180 US product page (runtime formula and compressor caveat).
• Anker SOLIX C1000 US product page.
• US CPSC, Portable Generator Hazards, Publication 5123.
• Ready.gov, Power outages.