Fridge Backup Calculator
How long can a portable power station keep your fridge cold during a power outage? Select your fridge type and battery size. This calculator accounts for compressor duty cycles — fridges don't run at full power continuously.
Estimated Fridge Runtime
36.5
hours
Mini-Fridge on 1024Wh battery
Surge requirement
130W
Your power station must handle at least 130W surge when the compressor kicks on.
How we calculated this
- Compressor watts: 65W
- Duty cycle: 33% (compressor cycles on/off)
- Average draw: 21W
- Efficiency: 85%
- Reserve: 10%
- Usable: 870 Wh → After reserve: 783 Wh
Real fridge runtime varies heavily by ambient temperature, door openings, thermostat setpoint, and compressor age.
Stations that can handle a mini-fridge (130W surge)
These stations meet or exceed 1024Wh. Prices link to Amazon.
Best fit:EcoFlow DELTA 3 Plus
1024 Wh battery · 1800W output · 1000W solar · 12.5 kg
$799
Buy on Amazon
Anker SOLIX C1000
1056 Wh battery · 1800W output · 600W solar · 13 kg
Fridge Runtime
36.5 hrs
Surge needed
130W
FAQ
Why does a fridge run much longer on a power station than its watt-hours suggest?
A refrigerator's compressor cycles on and off to hold temperature rather than running constantly — for a full-size fridge it's typically active only about 30% of the time. So although it may pull 100-250W while the compressor runs, it averages only roughly 30-75W over a full hour. Runtime is based on that lower average draw, which is why a fridge lasts far longer than a simple 'capacity ÷ running watts' estimate. The calculator above applies the duty cycle for you.
What surge rating do I need to start a refrigerator?
A full-size fridge runs at 100-250W, but its compressor can spike to roughly 400-1200W for a fraction of a second at startup — so you want a power station rated for at least 1500W surge (peak) to start it reliably, even though the continuous draw is far lower. If the surge rating is too low, the startup spike trips the station's overload protection and it shuts off. See our guide on surge vs running watts for more.
How does this fridge backup calculator estimate runtime?
It divides the station's usable energy by the fridge's average draw. Usable energy is about 75-80% of the rated watt-hours after inverter efficiency loss (around 15% on AC) and a 10% reserve buffer. Average draw is the fridge's running watts multiplied by its compressor duty cycle. Choose your fridge type and battery size above to see an estimate for your setup.