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Power Station Runtime Calculator

Estimate how long a portable power station may supply up to three loads. Include the time each load is actually running.

Read the method and its limits

Last reviewed 26 September 2026
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Station and loads

Defaults of 90% usable capacity and 85% output efficiency are illustrative AC planning assumptions. Check the manual or measure your setup. DC output may differ.

Load 1
Load 2
Load 3

For a continuously running device, enter 100%. For a cycling device, use a measured share of the hour. Enter 0 W for unused rows. Rating comparisons are simple checks, not proof that a motor will start.

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Method

How the estimate works

For each load, average W = running W x percentage of each hour / 100. Add those averages. Estimated hours = station Wh x usable capacity fraction x output efficiency / combined average W.

Worked example: a 1,000 Wh station with 90% usable capacity and 85% output efficiency delivers an estimated 765 Wh. A 60 W router running continuously and a 100 W appliance running half the time average 110 W together. Estimated runtime is 6.95 hours.

All listed running watts are added for the conservative continuous output check. The startup check compares only the combined values you supply. A short motor surge can still trip a station despite a favourable numerical comparison.

Sources

Method and safety evidence

  1. US Department of Energy: Battery chargers and external power supplies technical support documentEnergy and capacity units. Checked 26 September 2026.
  2. EcoFlow: Test your power station runtime before an emergencyRuntime estimate, output ratings and measurement. Manufacturer explanation checked 26 September 2026.
  3. EcoFlow: Portable power station for a sump pumpCycling loads, conversion losses and startup limitations. Manufacturer explanation checked 26 September 2026.
  4. Electrical Safety First: Power banks and portable chargersGeneral lithium battery use and damage cautions. Checked 26 September 2026.

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