Start with the refrigerator, not the battery
Find the refrigerator measured or rated running watts and, when available, its starting requirement. A power station continuous AC rating needs to cover normal operation, while its surge capability needs enough headroom for compressor startup.
Estimate battery capacity
Battery capacity is usually listed in watt-hours (Wh). A simple planning estimate is usable watt-hours ÷ average watts = hours. For example, a 2,000Wh-class battery at an assumed 85% usable efficiency provides about 1,700Wh for planning. A device averaging 100W would therefore have a theoretical estimate near 17 hours. Real refrigerators cycle on and off, so actual results vary.
What changes the result?
Room temperature, refrigerator size, compressor cycling, door openings, inverter losses, battery temperature and other connected loads can all change runtime. Treat calculations as planning estimates rather than guarantees.
Useful size range to compare
For outage planning, compare the appliance requirements against several power-station sizes rather than buying from battery capacity alone. Our Product Hunter pages include runtime calculators and specification snapshots for currently tracked portable power products.