Power Station Runtime Calculator
Enter your power station's watt-hour capacity and a device's wattage to estimate how many hours it will run before recharging.
Most power stations lose 8-15% to inverter heat plus a small battery-management reserve — 85% is a reasonable typical default.
Estimated runtime
8h 30m
Usable capacity
850 Wh
This is a planning estimate based on the device's steady running watts — it doesn't account for a motor-driven appliance's brief starting surge (see the Surge Watts Calculator), or for battery capacity that gradually declines with age and cold temperatures.
How the Power Station Runtime Calculator works
Enter your power station's watt-hour capacity and the device's running wattage — or quick-pick a common appliance to fill in a typical wattage automatically — and the calculator estimates how many hours it will run before the battery is depleted.
The estimate applies a typical 85% usable-efficiency factor (adjustable) to account for inverter and battery losses, since a power station's rated capacity is never 100% available as usable AC power.
Frequently asked questions
Why does the calculator use only 85% of my power station's rated capacity?
A power station's advertised watt-hour rating is the raw battery capacity, but converting that stored DC energy into usable AC power always loses some energy as heat in the inverter, and the battery management system holds back a small reserve to protect the cells — 85% usable is a widely used, reasonable typical estimate for that combined loss.
Does this account for a device's startup surge?
No — this calculator estimates runtime from steady running watts only. A motor-driven appliance like a refrigerator or pump also needs the power station's surge (peak) rating to be high enough for its brief startup spike; see the Surge Watts Calculator for that separate consideration.
Why did my actual runtime come out shorter than the estimate?
Real-world runtime is also affected by battery age, cold temperatures (which reduce usable capacity), and a device that draws more than its rated running watts under certain conditions — treat this calculator's result as a planning estimate, not an exact guarantee.