Does watt-hour runtime include starting surge?

No. Runtime math uses running watts. Verify inverter surge rating separately for refrigerators, pumps, or compressors.

How much usable capacity should I assume?

A conservative planning range is often 75% to 90%, depending on inverter losses, battery management limits, temperature, and load size.

Can this calculator size medical backup power?

It can help estimate energy, but medical users should check device manuals and clinician or provider guidance before relying on any battery.

Planning tool

Portable Power Station Runtime Calculator

Estimate power station runtime for essential outage loads using watt-hours, load watts, and usable-capacity assumptions.

Estimated runtime Run the calculator

This estimate does not confirm starting surge, device compatibility, medical suitability, or generator safety.

Usable watt-hours: —
Load category: —
Solar recharge reality check: Panel output, weather, shade, and input limits control recharge speed.

Essential load presets

Use measured watts whenever possible

Router + modemOften 15–30W. Good first target for small power stations.

RefrigeratorRuntime depends on cycling and starting surge; verify inverter surge rating separately.

CPAP setupHumidifier and heated hose can sharply increase watts; check the device manual.

Do not size from watt-hours alone

Check starting surge, AC vs DC efficiency, pass-through charging limits, safe indoor use, carbon monoxide rules for generators, and whether a medical device needs provider guidance.

Read refrigerator backup guide

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