Fast estimate
A typical planning range for a home refrigerator is 120W × 35% duty cycle, but your real number can vary. For 24 hours, that rough load is about 1,000Wh before inverter loss and safety buffer.
Formula used
average watts = running watts × duty cycle
battery target Wh = average watts × hours ÷ 0.85 × 1.15Example fridge-only targets
| Goal | Rough target | Likely class |
|---|---|---|
| 8 hours | ~450Wh | Compact may work |
| 12 hours | ~680Wh | 700–1,000Wh class |
| 24 hours | ~1,360Wh | 1,200–2,000Wh class |
Buying rule
If the refrigerator is the main reason for the purchase, do not buy the smallest unit that “can run a fridge.” Buy for the number of outage hours you actually need, with reserve.