Altcoin Season Index: What the Number Actually Counts

The phrase 'altcoin season'

Altcoins are all the coins other than bitcoin, and altcoin season refers to a stretch when other coins broadly rise more than bitcoin. The opposite, when bitcoin leads the rest, is called bitcoin season. There is no official definition, so each source uses its own yardstick. To answer 'is it altcoin season?' you first have to settle which number you mean. This guide works through three common methods as defined and explains why they can give different answers on the same day.

Comparing top coins with bitcoin

The most widely quoted method is the Altcoin Season Index from blockchaincenter.net. It takes the top 50 coins by market capitalisation, excludes stablecoins and asset-backed tokens such as WBTC, and expresses the share that outperformed bitcoin over the past 90 days on a scale of 0 to 100. A reading of 75 or more is altcoin season, 25 or less is bitcoin season, and anything between is neither. Because it counts how many coins beat bitcoin, it separates a market where a few coins surged from one where most coins edged ahead. But since it looks at the whole 90-day window, its verdict is always the result of the past three months.

• Universe: top 50 by market cap (excluding stablecoins and asset-backed tokens)
• Measure: share that beat bitcoin over the past 90 days
• 75 or more: altcoin season; 25 or less: bitcoin season
• The verdict reflects the past 90 days

Reading it from bitcoin dominance

Bitcoin dominance is bitcoin's share of total crypto market capitalisation. When it falls, other coins' share has grown, which is often read as money rotating into altcoins. But stablecoins are in the denominator too, so if people sell coins for stablecoins in a falling market, bitcoin dominance can drop without any altcoin rising. Looking at dominance with stablecoins excluded is less confusing. The altseason index on this site's Dominance Radar is a simple conversion of dominance to 0 to 100, calculated as (70 − BTC dominance) ÷ 40 × 100, so it is a different number from the top-50 comparison index above.

Reading it from the ETH/BTC ratio

The ETH/BTC ratio, ether's price divided by bitcoin's, shows in a single line whether the leading altcoin is stronger or weaker than bitcoin. It is simple to compute and easy to view over any period. But it is one coin's relative price, so news or product launches specific to Ethereum feed straight into it. While ETH/BTC rises, most other coins may still be weaker than bitcoin, so it is hard to use as a number for the whole market.

Why the numbers differ on the same day

The three methods measure different things, so they give different answers on the same day. The top-50 comparison counts coins, dominance looks at market cap share, and ETH/BTC is one coin's price ratio. Their time frames differ too: an index based on 90-day performance and today's dominance do not share a time axis. Market cap grows not only with price but with newly released supply, so a coin whose price has not risen can still grow in market cap and pull dominance down. Which coins are excluded and how many are included also change the result.

• What is counted: number of coins, market cap share, one coin's price ratio
• Period: 90-day performance and today's share are on different time axes
• Market cap also grows with newly released supply
• Exclusions and the number of coins change the result

Common mistakes

Because of its name, an altcoin season index is easily read as saying something about what comes next. Followed through its definition, though, every version is a summary of a period that has already passed.

• Altcoin season is coming soon: the index counted the past 90 days
• Falling dominance means altcoins will rise: stablecoins' share may have grown
• If the top 50 lead, my coin will rise: individual coins can move very differently
• Seasons return on a cycle: no such cycle has been established

Checking it with this site's live tools

The Dominance Radar uses CoinGecko data to show the market cap shares of bitcoin, ether and altcoins and BTC dominance excluding stablecoins, how many of the top 50 altcoins rose more or fell less than bitcoin over a chosen 7-day, 30-day, 200-day or one-year period, and the BTC-relative price trends of ETH, SOL, BNB and XRP. Crypto Market Breadth counts how many coins on Binance's spot USDT market rose or fell and what share sit above their moving averages, showing whether a rise is broad or concentrated in a few coins. The Crypto Correlation Matrix shows how closely altcoins moved with bitcoin and their beta.

Summary and caution

Altcoin season has no fixed definition, and the top-coin comparison index, bitcoin dominance and the ETH/BTC ratio each count different things over different periods. Whichever number you use, check what it counts and over what period; the verdict summarises past moves and does not point to future direction. This guide explains how to read indicators; it is not investment advice and does not recommend trading any coin.