Bitcoin dominance: what it is and how it signals altcoin season

Bitcoin dominance (BTC.D) is bitcoin's share of the total crypto market cap: BTC's market capitalization divided by the market cap of all cryptocurrencies, expressed as a percentage. As of 4:00 AM ET on October 13, 2026, it stood at 59.8% according to CoinGecko data, with roughly $1.69 trillion of a $2.82 trillion market sitting in bitcoin. Rising dominance means bitcoin is outperforming the rest of the market; falling dominance means altcoins are catching up. On its own, though, the number doesn't call an altcoin season — stablecoins and broad sell-offs move it too.

This guide covers how bitcoin dominance is calculated, why different sites show different numbers, how altcoin season is formally defined, and what the picture looked like in October 2026.

How is bitcoin dominance calculated?

The formula is simple:

BTC dominance = bitcoin market cap ÷ total crypto market cap × 100%.

Bitcoin's market cap is price times circulating supply. As of October 13, 2026, about 20.1 million BTC were in circulation out of a 21 million cap (see our bitcoin halving explainer for how issuance shrinks). The denominator is the sum of every coin a given data provider tracks.

CoinMarketCap's explainer gives the textbook case: if bitcoin is worth $60 billion in a $100 billion market, dominance is 60%. The key point is that it's a ratio, not a price. Bitcoin can fall while its dominance rises, as long as everything else falls faster.

Why do CoinGecko, CoinMarketCap and TradingView show different numbers?

The numerator is nearly identical everywhere; the denominator isn't. Each aggregator defines "the whole market" with its own coin list:

That's why readings differ by a fraction of a point on a normal day and by several points at historical extremes. The January 2018 low is the clearest example: CoinMarketCap's explainer puts it at 32.8%, Decrypt reported 33% on January 8, 2018, and Cointelegraph, citing TradingView, gave 36.7%. The rule: only compare dominance readings from the same source.

What moves bitcoin dominance: five scenarios

Dominance changes when bitcoin and the rest of the market move at different speeds. Starting from 59.8% (October 13, 2026) and treating "the rest of the market" as one block:

The first three rows land at almost the same number but describe very different markets: a rally, a stall and a crash. The last row is the trap — dominance drops while altcoins have gained nothing. So check whether the total market is growing, not just BTC.D. You can compare live price and market cap on the CoinLab dashboard and the Bitcoin page.

How stablecoins distort bitcoin dominance

Stablecoins sit in the denominator even though they're dollars parked inside crypto, not bets on altcoins. Per CoinGecko, on October 13, 2026 Tether (USDT) made up 6.5% of the total market and USDC 2.6% — about 9.1% combined.

Two consequences follow:

1. Dominance is understated. Strip just USDT and USDC out of the denominator and bitcoin's share on the same date is about 65.8%, not 59.8%.
2. BTC.D can slide during a sell-off by itself. Stablecoins hold at $1. If everything except stablecoins drops 20%, bitcoin dominance falls from 59.8% to 58.5% — even though no altcoin outperformed bitcoin. That's a flight to dollars, not an altcoin season.

That's why many analysts track a stablecoin-excluded version of dominance or watch total stablecoin supply alongside it.

What is altcoin season and how is it measured?

Altcoin season is a stretch when most altcoins outperform bitcoin. There's no official threshold, but two popular indexes use the same logic: what share of large coins beat bitcoin over the past 90 days.

Unlike dominance, these indexes measure breadth rather than capital share: how many coins beat bitcoin. High dominance and a low altseason reading usually go together, but not always — a few large altcoins can rally while a hundred smaller ones lag.

Another quick gauge is the ETH/BTC pair: ether is the largest altcoin, and past altcoin seasons tended to start with it outperforming. Compare the two networks on the Bitcoin and Ethereum pages.

Bitcoin dominance history: key levels

Historical markers, each from its own source:

• February 2017: 85.4%, then about 40% by June 2017 during the ICO boom (CoinMarketCap Academy).
• January 2018: all-time low of 32.8% to 36.7%, depending on the source (see above).
• September 2019: around 70% after the bear market (CoinMarketCap Academy).
• May 2021: 40.3% per CoinMarketCap, then below 40% in December 2021 (Cointelegraph).

The pattern: dominance lows came late in bull markets, when money chased speculative altcoins, and highs came in bear markets, when capital rotated back into bitcoin or left crypto entirely. That's an observation from two cycles, not a law.

Bitcoin dominance on October 13, 2026

Data as of 4:00 AM ET, October 13, 2026:

• bitcoin dominance: 59.8%, ether: 11.0% (CoinGecko);
• total crypto market: $2.82 trillion, down 3.6% over 24 hours; USDT and USDC about 9.1% of the market;
• dominance excluding USDT and USDC: about 65.8%;
• Altcoin Season Index: 47 out of 100, "neutral"; it left Bitcoin Season territory on September 2, 2026;
• ETH/BTC on Binance: 0.0301, versus 0.0296 ninety days earlier (+1.8%).

The read: bitcoin still holds roughly three-fifths of the market, altcoins have stopped lagging across the board, but the formal altseason threshold of 75 is a long way off. For sentiment on the same day, see our crypto Fear and Greed Index guide.

Common mistakes

• Reading a falling BTC.D as altseason. Dominance also falls when bitcoin drops while stablecoins hold still. Check total market cap.
• Mixing sources. CoinGecko, CoinMarketCap and TradingView build the denominator differently; a one-point gap is methodology, not a market move.
• Ignoring new supply. Big token listings and stablecoin issuance grow the denominator and shrink BTC's share without any money rotating.
• Waiting for a magic level. Neither 60% nor 50% is a trigger: dominance reached about 70% in 2019 and dropped below 40% in 2018.
• Using dominance alone. Pair it with ETH/BTC, an altseason index, stablecoin supply and spot bitcoin ETF flows, which since 2024 have added demand specifically for BTC.

FAQ

Where can I check bitcoin dominance? On CoinGecko, CoinMarketCap and TradingView (ticker CRYPTOCAP:BTC.D). The CoinGecko reading is on the CoinLab dashboard, refreshed every 15 minutes.

What counts as high bitcoin dominance? There's no formal scale. Since 2018 the range has run from roughly 33⁠–⁠37% up to 70%; around 60% on October 13, 2026 sits in the upper half.

Does falling dominance mean it's time to buy altcoins? No. It's only a shift in shares — it can reflect altcoins rising, bitcoin falling or stablecoin inflows.

How is dominance different from the Altcoin Season Index? Dominance is cap-weighted and driven by the biggest coins. The altseason index counts how many of the top 50 or top 100 coins beat bitcoin over 90 days.

This is not investment advice.