Free planning tool
Portable power runtime calculator
Estimate the usable watt-hours needed for one appliance or a combined steady load. This is a sizing starting point, not a promise of real-world runtime.
Energy used by the load
480 Wh
Indicative battery capacity
565 Wh
Before ageing, temperature, standby and surge allowances.
Three checks the watt-hour result cannot answer
- Continuous output: the unit must support at least the combined running watts.
- Starting surge: fridges, pumps and some tools can briefly require much more power.
- Suitability and safety: do not power medical, heating or safety-critical equipment from a general calculator.
Actual runtime varies with inverter losses, battery management limits, temperature, battery age, load behaviour and manufacturer settings.