What is the Altcoin Season Index?
The Altcoin Season Index measures whether altcoins are outperforming Bitcoin across a rolling 90-day window. It condenses one question, whether capital is rotating out of Bitcoin and into alts, into a single number between 0 and 100. A reading below 25 indicates Bitcoin Season, where BTC leads returns and dominance climbs. A reading above 75 marks Altcoin Season, where most large-cap altcoins, from Ethereum to Solana and XRP, are beating Bitcoin. The live score, 7-day average and 30-day range above show where the market sits today.
How the Index is Calculated
The score is built from the top 100 cryptocurrencies by market capitalisation, with stablecoins and wrapped or pegged assets removed. Each remaining coin's 90-day return is measured directly against Bitcoin's over the same window.
- Pull the top 100 coins by market cap, then filter out stablecoins like USDT and wrapped tokens like WBTC.
- Compute the 90-day price return for every coin and for Bitcoin.
- Count how many coins outperformed BTC across that window.
- Express that count as a percentage to set the final score from 0 to 100.
A score of 60 means 60 of the 100 tracked coins beat Bitcoin over the past 90 days.
Interpreting the Score
- 0 to 25, Bitcoin Season: Capital concentrates in BTC. Altcoins typically underperform Bitcoin and dominance rises.
- 25 to 75, Neutral: A transition zone. Selective altcoins can run, but no broad rotation is confirmed.
- 75 to 100, Altcoin Season: Risk appetite has moved outward and most large-caps are outpacing Bitcoin.
The over-time chart above carries more weight than any single print, since a multi-week climb confirms a regime change that one volatile day can fake.
Using the Index in Strategy
The index works best as a regime filter rather than a buy or sell signal. Persistent prints below 25 coincide with rising Bitcoin dominance and underperforming altcoin allocations. Sustained moves above 75 tend to arrive late in a market cycle, after liquidity has already broadened. Read it alongside the Crypto Fear and Greed Index and funding rates for a fuller picture of sentiment and positioning before adjusting exposure.
Limitations to Consider
Because the index weights every qualifying coin equally, a few outsized rallies in low-cap names can lift the score even when the broader market is muted. The 90-day lookback also smooths over short-lived rotations, so the reading can trail fast-moving regime shifts by several weeks. Coverage differs across platforms too, so a score of 40 on one tracker may register as 35 on another. Treat it as a confirmation tool that works best beside other indicators rather than a standalone signal.
Final Thoughts
The Altcoin Season Index gives investors a simple, repeatable way to frame relative performance between Bitcoin and the rest of the market. It will not call tops or bottoms, but tracking the score over time helps cut through narrative noise and ground portfolio decisions in observable behaviour rather than headlines.
