Definition
Altcoin season is an informal name for a period when a large share of altcoins perform better than bitcoin. It has no single official definition, and different trackers measure it in different ways.
How it works
The idea is relative performance, not simply rising prices. During an altcoin season, many coins other than bitcoin post larger gains than bitcoin over the same period, and bitcoin dominance often falls as value spreads to the rest of the market. Altcoins can also beat bitcoin in a falling market by dropping less, but the term is mostly used for rising markets.
Some indexes turn the idea into a number. A typical approach takes a list of large coins, leaves out bitcoin and usually stablecoins, measures each coin's return over a fixed window, and calls it altcoin season when a set share of them beat bitcoin. The list size, window length and threshold all vary between providers, so one index may show altcoin season while another does not.
Altcoin season can only be confirmed in hindsight, because every measurement looks back over a window that has already passed. By the time an index crosses its threshold, much of the outperformance has already happened. The label describes what the market has done, not what it will do next, and past periods described this way have differed widely in length and strength.
Example (hypothetical numbers)
Suppose a hypothetical index compares 40 large altcoins with bitcoin over the last 60 days and calls it altcoin season when at least 75% of them did better.
If 32 of the 40 outperformed bitcoin: 32 ÷ 40 = 80%, which is above 75%, so the index signals altcoin season.
Over a 90-day window, only 24 of the same 40 outperformed: 24 ÷ 40 = 60%, which is below the threshold.
The same market can be called altcoin season or not, depending on the window and threshold chosen.
Common mistakes
- Treating an index reading as a forecast rather than a summary of past performance.
- Assuming every altcoin rises during altcoin season, when the measure only counts a share of coins.
- Comparing readings from indexes that use different coin lists, windows or thresholds.
Related calculators
This glossary is for education only and is not investment advice. Examples use hypothetical numbers.