Free planning tool
Portable Power Station Calculator
Work out roughly what capacity you need, estimate how long a given battery will run your setup, and see which of the portable power stations we research fit those numbers. Every assumption is shown and editable.
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How the calculator works
For each device it multiplies running watts by hours of use and by quantity, then adds those figures together. That total is your estimated device energy. It divides that by an efficiency assumption to estimate the battery capacity required, and optionally multiplies the result by a planning headroom percentage. Nothing is added silently — every number feeding the result is visible in the form above.
Understanding watts vs watt-hours
Watts (W) describe how fast a device draws power at any moment. Watt-hours (Wh) describe a quantity of energy — roughly, watts multiplied by time. A power station's capacity is quoted in watt-hours, while its inverter's continuous output is quoted in watts. Both matter: capacity decides how long you can run something, output decides whether you can run it at all.
Surge or startup power is a brief spike above the running figure. Compressors, pumps and some motors draw it when they start. A unit can have plenty of capacity and still trip on a startup spike it cannot cover, which is why the calculator tracks the highest surge you enter separately rather than inventing one.
Why real runtime varies
Inverter losses, the battery management system, temperature, battery age and how your equipment actually behaves all affect what you get in practice. Cycling appliances complicate it further: a fridge rated at 150W does not draw 150W continuously, so its daily energy use is far lower than watts multiplied by 24. Treat these results as planning estimates, not predictions.
How much planning headroom should I use?
Around 20% is a reasonable starting point for most people. Use more if your wattages are guesses, if you expect cold conditions, or if you may add devices later. Use less if you have measured your equipment and your needs are fixed. Headroom is a buffer for uncertainty, not a specification requirement.
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