Each scenario below is a worked load with the reasoning shown: which devices, how many hours, what the daily watt-hours come to, and which limit fails first. Every one of them opens in the calculator with the load already filled in, so you can change a number and watch the answer move.
Device wattages come from the library on the calculator page, and most of them are published engineering ranges rather than measurements. Treat every figure as a planning estimate.
What size battery runs a CPAP for one night without a humidifier?
A CPAP running dry draws far less than most people assume. The number that decides the purchase is a full night of hours, not a peak wattage, and the humidifier setting changes it more than any other choice.
How much more battery does a CPAP need with the humidifier on?
The heated humidifier is the largest variable in CPAP backup sizing. Treating it as the same load as a dry machine understates the battery by enough to matter, which is why the device library keeps them as two separate entries.
What size power station runs a fridge, router, and lights during an outage?
The compressor start, not the daily energy, is the usual reason a station fails this load. A unit with enough watt hours can still refuse to start a fridge, and that is the failure this page exists to make visible before you buy.
What size portable power station do I need for a day of camping?
A camping load is dominated by the 12V fridge and by whether you plan to work from the site. It is a gentler load than a home outage, with a much smaller startup surge.
Can a portable power station run a circular saw?
Power tools invert the usual advice. The running draw is large, but the motor startup is larger, and a station that covers the watts can still trip on the first trigger pull. This is the clearest case where a boost rating is not the same thing as a surge rating.
These are the loads people ask about most often, not a generated list. If your load is not here, thecalculatortakes any combination, and themethodologypage records the formulas and constants behind the numbers.