Rated output is what the generator sustains continuously; maximum output is a short peak it tolerates while something starts. Sizing a load list against the maximum figure is the classic way to buy a generator that cannot run what it started.
Generators are sold on their biggest number, which is almost always the one you should not be sizing against.
The two output figures
The rated, or continuous, figure is what the machine delivers hour after hour. The maximum, or peak, figure covers the surge of a motor starting. Your total continuous load belongs under the first number, with the surge of the largest motor fitting under the second.
Runtime figures need their load
A runtime is always quoted at a stated load — often a fraction of the rated output. The same tank at full load empties much faster. Comparing two runtimes means checking that both were quoted at the same fraction, which is not always the case.
Noise, distance and load
Noise is published in decibels at a distance, and the scale is logarithmic, so small numerical differences are larger than they look. A figure quoted at seven metres and one quoted at one metre are not comparable, and a figure with no distance at all is not a measurement.
What the manual governs
Where a generator may be run, how it is earthed, how it is refuelled and how it is stored are set out in the maker’s manual, and those instructions are stricter than any general advice. Exhaust makes this an outdoor machine, and this page will not qualify that sentence.
What people ask before they order
What is an inverter generator?
One that generates alternating current, converts it to direct current and rebuilds a waveform electronically. That lets the engine speed vary with the load, which changes noise and fuel use, and it is the type sold for sensitive electronics.
Is a published noise figure comparable between makers?
Only when the distance and the load are stated, because both change the result. A decibel figure without them compares to nothing.
Last reviewed 16 September 2026