Gulf Coast & Southeast
Hurricane season drives multi-day outage planning; size for humidity-heavy fridge cycling and longer backup windows.
Backup Power · US homeowners
Portable power station runtime calculator for home backup
Use this free calculator to estimate minimum battery capacity (Wh) for essential loads during outages. It accounts for running watts, device count, backup duration, and real-world efficiency loss.
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Live MVP Calculator
Portable Power Station Runtime Calculator
Estimate minimum battery capacity from running watts, device count, desired backup hours, and real-world efficiency.
For motor loads like refrigerators, check inverter surge rating separately.
How to use
Get a useful estimate in a few minutes
This tool is a screening calculator for US homeowners—not a substitute for licensed electrical, HVAC, or solar design work.
- List the devices you must keep running during an outage.
- Enter running watts (not surge) for each load or group.
- Set how many hours of backup you want.
- Compare the result against product Wh ratings and inverter surge specs.
Regional considerations across the United States
Climate, utility rates, housing stock, and outage patterns vary by region. Use these notes alongside your local quotes, permits, and installer guidance.
California & West
PSPS wildfire outages favor quiet indoor-safe backup without gas generators; essential-load Wh planning is common.
Northeast & Upper Midwest
Winter ice storms can last 24–72 hours; prioritize medical devices, heat-adjacent loads, and sump pumps where basements flood.
Texas & Central US
Grid stress events make dual-fuel or battery backup popular; match Wh to fridge + fan + router for overnight comfort.
Frequently asked questions
How many watt-hours do I need to run a refrigerator overnight?
Many refrigerators draw 100–200W while running. For 12 hours at 150W with 85% efficiency, plan for roughly 2,100Wh minimum—plus surge headroom for compressor starts.
Should I use running watts or surge watts?
This calculator uses running watts for runtime math. Check inverter surge rating separately for motor loads like refrigerators, sump pumps, and garage door openers.
Is a portable power station enough for whole-home backup?
Usually not for HVAC or electric heat. Essential-load backup—fridge, lights, router, CPAP—is the realistic use case for most portable stations.
Next Step
Email yourself this estimate checklist
Save the assumptions you used so you can compare contractor quotes, product shortlists, and next-step guides.