Bitcoin Dominance and Altcoin Season
What Bitcoin dominance measures, what altseason means, how the altcoin season index works and how to use both with signals.
Rayner5 min read19 September 2026Bitcoin dominance is one of the most watched numbers in crypto and one of the most misread. It is Bitcoin’s market value divided by the value of all cryptocurrencies. A falling dominance means altcoins are growing faster than Bitcoin, or falling more slowly. A rising one means the reverse. The altseason meaning most traders use builds on it: a stretch when most altcoins beat Bitcoin at the same time.
This guide explains how dominance is calculated and what distorts it, what altcoin season means and how the common index measures it, what past cycles looked like, and how to use dominance and the ETH/BTC ratio as a backdrop when choosing between Bitcoin and altcoin signals.
Bitcoin dominance is Bitcoin’s share of the total crypto market value. When it falls, money is flowing towards altcoins relative to Bitcoin. Altcoin season, or altseason, means a period when most large altcoins outperform Bitcoin, often defined as 75 percent of the top 50 coins beating Bitcoin over 90 days. Dominance is a backdrop for signals, not a timing tool.
How Bitcoin dominance is calculated
Bitcoin dominance = Bitcoin market value ÷ total crypto market value
| Bitcoin value | Total market | Dominance |
|---|---|---|
| 1.2 trillion dollars | 2.2 trillion dollars | about 55 percent |
| 1.2 trillion dollars | 2.5 trillion dollars | 48 percent |
| 1.0 trillion dollars | 1.6 trillion dollars | 62.5 percent |
Figures are illustrative. The second row shows dominance falling while Bitcoin’s own value is unchanged, because the rest of the market grew. The third shows dominance rising in a falling market, because altcoins fell harder.
What distorts dominance
| Factor | Effect |
|---|---|
| Stablecoins | Their value counts in the total. When traders sell into stablecoins, dominance can fall without any altcoin strength |
| New tokens | Every new listing adds to the total, pulling dominance down slowly |
| Data provider | Different sites include different coins, so readings differ by a few points |
| Thinly traded tokens | Market value on paper can overstate what could actually be sold |
Many traders also watch dominance excluding stablecoins, which gives a cleaner picture of Bitcoin against other volatile coins.
Altseason meaning
Altcoin season, or altseason, is a period when most altcoins outperform Bitcoin. The best known index defines it as at least 75 percent of the top 50 coins, excluding stablecoins, outperforming Bitcoin over the previous 90 days. The opposite, 25 percent or fewer, is called Bitcoin season.
| Index reading | Label | What it means |
|---|---|---|
| 75 or above | Altcoin season | Most large altcoins beating Bitcoin over 90 days |
| 26 to 74 | Neither | Mixed performance |
| 25 or below | Bitcoin season | Bitcoin beating most altcoins |
Because it looks back 90 days, the index confirms an altseason after it has started. It does not predict one.
What past cycles looked like
| Period | What happened |
|---|---|
| Late 2017 to early 2018 | Dominance fell to roughly a third of the market as altcoins surged, then altcoins fell far harder than Bitcoin in the bear market that followed |
| Early 2021 | Dominance fell to around 40 percent during a broad altcoin rally, before a sharp reversal in May |
| 2023 to 2024 | Dominance rose for long stretches, helped by the arrival of US spot Bitcoin ETFs |
The pattern in past cycles: Bitcoin leads, Ether follows, smaller coins run last, and the reversal is fastest for the coins that ran furthest. Past cycles are a guide to behaviour, not a forecast.
Using dominance with signals
| Dominance | ETH/BTC | Backdrop | Signal preference |
|---|---|---|---|
| Rising | Falling | Money favouring Bitcoin | Bitcoin buys over altcoin buys |
| Falling | Rising | Money rotating into altcoins | Altcoin buys have a tailwind |
| Rising in a falling market | Falling | Altcoins falling harder | Avoid altcoin buys. Altcoin sells have a tailwind |
| Falling while stablecoin share rises | Any | Traders moving to cash | Caution on all buys |
The ETH/BTC ratio is explained in Ethereum signals. Neither measure says when to enter. The signal’s own entry, stop and targets still decide that, and altcoin positions still need the smaller sizing covered in altcoin signals.
Common misreadings
- Treating a small daily change as a trend
- Reading falling dominance as altcoin strength when stablecoins are growing
- Buying small coins because “altseason is coming”
- Using the altcoin season index to time entries, when it looks back 90 days
- Comparing readings from different data sites
Groups that promote an imminent altseason to sell small coins are covered in crypto signal scams.
Keep reading
- Altcoin signals sizing smaller, riskier coins
- Ethereum signals ETHUSD and the ETH/BTC ratio
- Bitcoin signals the coin every cycle starts with
- Crypto trading signals live signals and sizing
Frequently Asked Questions
What is Bitcoin dominance?
Bitcoin’s share of the total cryptocurrency market value, calculated as Bitcoin’s market value divided by the value of all coins. It shows whether money is favouring Bitcoin or the rest of the market.
What is the altseason meaning in crypto?
Altseason, or altcoin season, is a period when most altcoins outperform Bitcoin at the same time. A common definition is 75 percent of the top 50 coins beating Bitcoin over 90 days.
Does falling Bitcoin dominance mean altseason?
Not always. Dominance also falls when traders move into stablecoins, which count in the total. Check whether altcoins are actually rising against Bitcoin.
How is the altcoin season index calculated?
The best known version checks how many of the top 50 coins, excluding stablecoins, outperformed Bitcoin over the past 90 days. At 75 percent or more it reads as altcoin season.
What is a good level of Bitcoin dominance?
There is no good or bad level. The direction matters more than the number, and readings differ between data providers by a few points.
Can I trade Bitcoin dominance directly?
Some platforms offer dominance based products, but most traders use it as a backdrop for choosing between Bitcoin and altcoin signals rather than trading it.
Why do altcoins fall harder when dominance rises in a sell off?
They usually have thinner liquidity and more speculative holders, so selling pressure pushes their prices down further than Bitcoin, lifting its share of the total.
