BLUETTI
AC70P
Estimated runtime: 12.2 hours
864Wh1,000W10.2kg
PORTABLE POWER STATION TOOL
Portable power station
runtime calculator.
Estimate the battery capacity needed to run a refrigerator, CPAP, heated blanket, laptop, projector, or another appliance—then compare products that meet both the capacity and output requirement.
INTERACTIVE CALCULATOR
Calculate the battery size you need.
Enter the continuous wattage from the appliance label and the number of hours you want it to run. The estimate reserves 15% for AC conversion losses.
MINIMUM RECOMMENDED CAPACITY848 Wh
60W × 12 hours ÷ 0.85 efficiency
PRODUCT MATCHES5 suitable options
Sorted by the smallest capacity that clears both the runtime and rated-output requirements.
EcoFlow
DELTA 2
Estimated runtime: 14.5 hours
1,024Wh1,800W12kg
EcoFlow
DELTA 3 Plus
Estimated runtime: 14.5 hours
1,024Wh1,800W12.5kg
Anker SOLIX
C1000
Estimated runtime: 15.0 hours
1,056Wh1,800W12.9kg
BLUETTI
AC180
Estimated runtime: 16.3 hours
1,152Wh1,800W16kg
Runtime is an estimate, not a guarantee. Motor startup surge, temperature, battery age, inverter efficiency, and appliance cycling can change the result. Confirm rated and surge output before purchase.
THE TWO NUMBERS THAT MATTER
Capacity tells you how long.
Output tells you if it runs.
Watt-hours (Wh)
Wh is the battery energy budget. A 60W car fridge running continuously for 12 hours consumes 720Wh before conversion losses. Because fridges cycle on and off, real use may be lower.
Watts (W)
Rated output must clear the device's continuous draw. Refrigerators, pumps, and tools can also need a short startup surge, so confirm the manufacturer's surge rating.
Efficiency and reserve
This calculator uses 85% efficiency. Add more margin for cold weather, an older battery, multiple devices, or a trip where running out of power is not acceptable.
FAQ
Runtime questions
How do I calculate portable power station runtime?
Multiply battery watt-hours by an efficiency factor, then divide by the appliance watts. WattMatch uses 0.85 for a simple AC estimate: battery Wh × 0.85 ÷ appliance W.
Why does the calculator divide by 0.85?
A power station cannot deliver every rated watt-hour through its AC inverter. The 85% assumption leaves a practical allowance for conversion losses, although actual efficiency varies by load and model.
Does rated output matter as much as capacity?
Yes. Capacity estimates how long a device may run, while rated and surge output determine whether the station can start and operate that device at all.
What size power station should I buy for a CPAP?
Check the CPAP label or adapter wattage and include the humidifier if you use it. A 40W device for 8 hours needs roughly 377Wh using the 85% assumption, before adding any safety margin.