Add 20–30% reserve
If the calculator says 900Wh, a 1,000–1,200Wh station is often a more comfortable starting point for real use.
Planning tool
Portable power station runtime calculator
Enter the load you actually plan to run. The estimate accounts for usable capacity, continuous output, startup surge, and appliance duty cycle.
Your setup
Pick a preset, then override the watts if you know the label value.
85%
85% is a planning default. Battery health, temperature, inverter losses, and load level can change real-world runtime.
Startup surge: compressors, pumps, and power tools can draw several times their running watts for a moment. If a surge rating is missing from our database, verify it with the manufacturer before buying.
Result
The two numbers answer different questions: runtime for your selected model, and capacity for your target hours.
Estimated runtime with selected model
— hours
Capacity needed for target hours
— Wh
Models that meet this target
How to use the result
Do not size to the exact number. Add reserve for battery aging, cold temperatures, and devices you forgot.
Check continuous watts
Capacity gets you through the hours; output watts determine whether the device can start and run at all.
Use real labels
Manufacturer wattage is approximate. The label on your appliance or a plug-in power meter is better than a generic estimate.
Methodology: runtime = (nominal Wh × usable efficiency) ÷ (running watts × duty cycle). Models with missing surge data are flagged for verification. This site is a planning tool, not a safety or medical device recommendation.