Power Station Runtime Calculator

Volume I  ·  May 2026  ·  618 words

Estimate how long a portable power station will run any device or combination of devices. The calculation accounts for inverter efficiency loss — energy consumed by the inverter itself before reaching your device. For a detailed treatment of where energy goes in a power station, see our efficiency analysis.

—
estimated runtime
Formula: Runtime = (Capacity Wh × Efficiency) ÷ Device Watts

Runtime estimates assume continuous device draw at the stated wattage. Devices with compressors (refrigerators, air conditioners) cycle on and off, extending actual runtime beyond the continuous-draw estimate. The refrigerator preset of 150W reflects the running wattage; actual duty cycle averages 30–40% in moderate ambient temperatures, effectively tripling the runtime shown. For a detailed refrigerator sizing analysis, see our refrigerator backup guide.

See Also Runtime Optimization: Extending Every Watt-Hour
5 Best Portable Power Stations for Emergency Backup
Watt-Hours, Amp-Hours, and Voltage Explained