The International Meteor Organization assigns the 2026 Perseid meteor shower a population index of 2.2.
The population index, written as r, describes how the number of meteors changes between brightness classes. It is a statistical measure used in meteor-shower analysis rather than a prediction of the exact number a single observer will see.
A lower population index indicates a relatively larger share of brighter meteors, while a higher value indicates more faint meteors relative to bright ones. The Perseids’ listed value of 2.2 is part of the IMO’s standard shower data alongside its radiant, velocity, and activity dates.
Actual observations can differ from the nominal index because moonlight, haze, light pollution, atmospheric transparency, and the observer’s visual limiting magnitude affect which meteors are detected.