How the altcoin season index works
The idea is simple: if most of the market's large altcoins are beating Bitcoin, money is rotating out of BTC and into alts. We take a basket of about 40 liquid Binance USDT pairs, measure each coin's 90-day return and compare it with Bitcoin's 90-day return. The index is the percentage of coins that did better than BTC. It updates every minute from daily closes, and the small chart shows how the reading evolved day by day.
- 75 – 100: altcoin season. Three quarters or more of the basket outperformed Bitcoin. Rotation is broad, not just one hot sector.
- 26 – 74: transition. Some alts lead, many lag. This is where most of the market cycle is spent.
- 0 – 25: Bitcoin season. BTC is outperforming almost everything; alts bleed against it.
Why a 90-day window — and why we also show 30 days
Ninety days filters out one-week pumps, which is why it is the standard lookback. The trade-off is lag: by the time the 90-day index prints 75, a lot of the move is often behind you. That is why the widget also shows the 30-day outperformers share and the full Alt Season score, which combines faster signals: falling Bitcoin dominance while BTC holds its trend, a rising ETH/BTC ratio above its 50-day EMA, and breadth (the share of coins in a daily uptrend) at or above 40%.
How to read it with the rest of the market
Alt seasons have historically come at the end of a longer chain. Gold and the US dollar move first, stocks follow, Bitcoin trends next, and only then does capital spread into large alts and small caps. If the index is rising while the dollar index is breaking higher, treat it with suspicion — dollar strength tends to cut rotations short. If it rises while dominance falls and ETH/BTC turns up, the rotation has broader support.
The table under the gauge lists every coin in the basket, its 90-day return and how far ahead of or behind Bitcoin it is. It is a quick way to see whether leadership is broad or concentrated in a handful of names.
Everything here is educational. The index describes the past 90 days; it does not predict the next ones. See the methodology for every rule and the disclaimer before acting on any signal.