The ratio of the average load power supplied over a specified time interval to the peak load power in that period. The load factor is usually expressed as a percentage.

The plant load factor relates specifically to an electrical generator or group of generators, and is the ratio of the actual number of electrical units (kilowatt-hours) supplied by the generators in a given time interval to the number that would have been supplied had the plant operated at its maximum continuous rating for that interval. This factor also is usually expressed as a percentage.