Free energy calculator
Portable Power Station Runtime Calculator
Estimate runtime for an AC or DC appliance from a power station rated in watt-hours.
Calculate your estimate
Change the example values to match your system.
Estimated result
Ideal—
Typical—
Conservative—
These are estimates, not guaranteed performance.
Formula and method
Typical hours = rated Wh × usable fraction × converter efficiency ÷ (load + standby).
Percent fields are entered as percentages; the calculation converts them to decimal fractions. Displayed results are rounded to two decimal places.
What the inputs mean
- Rated capacity (Wh)
- Enter rated capacity in Wh.
- Load (W)
- Enter load in W.
- Usable capacity (%)
- Enter usable capacity in %.
- Converter efficiency (%)
- Enter converter efficiency in %.
- Standby consumption (W)
- Enter standby consumption in W.
- Conservative retained fraction (%)
- Enter conservative retained fraction in %.
Worked example
A 1,000 Wh station with 90% usable capacity and 88% conversion efficiency supplies a 100 W load plus 5 W standby for about 7.54 typical hours.
Why the real result may differ
- Temperature, battery age, wiring resistance, and changing loads can move actual results away from the estimate.
- Manufacturer ratings may be measured under different test conditions. Measure the load when practical.
Common mistakes
- Do not confuse watts (power) with watt-hours (energy).
- Do not enter a percentage as a whole number: 90% is entered as 90 in this form and converted internally.
Frequently asked questions
Is this result guaranteed?
No. It is an engineering estimate; equipment, temperature, age, and duty cycle affect real performance.
Why are three estimates shown?
The ideal case ignores practical losses, while typical and conservative cases apply the efficiency and margin entered above.
Related tools
References
Last reviewed: August 6, 2026