TOOL / 01

Estimate the hours first.

Use battery watt-hours, average load, efficiency and a reserve. Change any field to see the planning estimate update instantly.

Estimated runtime10.4 hours

Assumes 85% efficiency and keeps 10% of the battery in reserve.

Planning estimate · not a manufacturer guarantee

How the estimate works

The calculator uses:

runtime = battery Wh × efficiency × (1 − reserve) ÷ load W

Battery capacity is the amount of stored energy published for the station, usually in watt-hours. Efficiency represents the energy lost in the inverter and conversion path. Reserve keeps the estimate from assuming the battery can be drained to zero.

A worked example

  1. 01
    Start with a 1,024 Wh battery rating from the station’s product sheet.
  2. 02
    Use a 75W average load for a hypothetical laptop-and-router setup.
  3. 03
    Keep the default planning assumptions of 85% efficiency and 10% reserve.
  4. 04
    The calculator estimates 10.4 hours: 1,024 × 0.85 × 0.90 ÷ 75.
  5. 05
    Test the real setup because the charger, display, standby draw and workload can move the average.

What can change the result

  • AC inverter losses versus a documented DC or USB-C path.
  • A compressor or motor starting repeatedly, even when average watts are modest.
  • Battery temperature, age, state of charge and the station’s low-battery cutoff.
  • Other devices connected at the same time, including chargers that appear idle.
  • A station’s economy mode or automatic shutdown when the load is small.

Related planning tools

Portable Power Station Wattage Calculator ↗Refrigerator runtime guide ↗CPAP compatibility guide ↗

FAQ

Should I enter the station’s full battery capacity?
Use the manufacturer’s watt-hour rating as a starting point, then use the efficiency and reserve fields to avoid treating all of that energy as delivered to the load. If the maker publishes usable Wh, that may be a better input; read the definition.
What efficiency should I use?
If you do not have measured data, use a conservative planning assumption and label it as such. The default is 85% for illustration, not a universal specification.
Can this calculate a refrigerator or sump pump?
Yes, if you enter a realistic average load. Check startup output separately and model cycling conservatively.

Planning guide · United States context · Updated September 20, 2026. Product lines, firmware, port standards and manufacturer limits change; verify the current manual before buying or connecting a load.