If you've ever searched for "when does altcoin season start" or "how to know if we're in altseason", the Altcoin Season Index is probably the first place you land. In one sentence, it's an indicator that looks at the last 90 days and answers a simple question: are altcoins beating Bitcoin, or is BTC dominating the cycle?

This guide explains exactly how the index works, how to read each band, classic signals that tend to precede a rotation, notable historical readings, and how the Alarm Crypto app sends you a phone notification the moment the value crosses your trigger.

What is the Altcoin Season Index?

The Altcoin Season Index is a relative performance indicator: it compares how much each top-50 altcoin appreciated against how much Bitcoin appreciated over the same window. The output is a percentage of how many altcoins outperformed BTC.

Unlike absolute-price indicators, the Altcoin Season Index doesn't answer "did altcoins rally?", it answers "are altcoins rallying harder than Bitcoin?". That distinction matters: in a generalized bear market every coin can fall, but if altcoins fall less than BTC, you'd still register a relative "altcoin season".

How the scale works

The index ranges from 0 to 100 and is divided into two main zones:

  • 0 – 24 — Bitcoin Season (strong): Bitcoin is outperforming the vast majority of altcoins. Money is concentrated in BTC.
  • 25 – 49 — Bitcoin Season: Bitcoin still beats most altcoins, but the gap is smaller.
  • 50 — Neutral: balance between Bitcoin and altcoin performance.
  • 51 – 74 — Altcoin Season: altcoins are outperforming Bitcoin. Money starts flowing to smaller projects.
  • 75 – 100 — Altcoin Season (strong): altcoins dominate. It's officially "altcoin season".

How the index is calculated

The math is simple: over the last 90 days, if 75% or more of the top 50 altcoins outperformed Bitcoin, we're in Altcoin Season. The index analyzes:

  • Relative performance — compares each altcoin's return against BTC's return over the same period
  • Top 50 altcoins — only counts the largest by market cap, excluding stablecoins (USDT, USDC, DAI, etc.) and BTC-pegged tokens (WBTC, BTCB)
  • 90-day window — long enough to filter short-term volatility without anchoring to stale data

Signals that tend to precede an altseason

Before the index crosses 75 and officially flips to "Altcoin Season", a few classic signals show up that experienced traders watch for:

  • Bitcoin dominance dropping — when BTC's share of total market cap falls below 50%, capital is generally rotating into altcoins.
  • ETH/BTC pair rising — Ethereum usually leads the rotation before the index reflects it. ETH gaining strength against BTC is the classic trigger.
  • Volume picking up in mid-cap altcoins — after BTC and ETH, money starts flowing into the "mid cap" range (top 20 to top 100).
  • Narratives gaining momentum — in 2024 it was memecoins, AI and RWA. In earlier cycles it was DeFi and NFTs. Every altseason has its dominant narratives.
  • Sentiment heating up — the market enters greed but hasn't yet hit extreme greed.

To complement this read, it's worth tracking the Crypto Fear & Greed Index, which measures overall market mood in parallel.

Historical readings worth remembering

Looking at concrete past examples helps calibrate expectations:

  • January 2018 — classic altseason peak after the massive late-2017 altcoin rally. Almost every top-50 altcoin had outperformed BTC over the previous quarter.
  • May 2021 — second notable altseason of the cycle. ETH, SOL, ADA and DOT were the stars.
  • November 2021 — market top, with global altseason and NFT mania.
  • 2022 to 2023 — extended period of "strong Bitcoin Season", with BTC keeping dominance above 50% and altcoins losing relative value.
  • Early 2024 — initial signals as spot Bitcoin ETFs were approved, plus the surge in Solana and memecoins.
Heads up

History doesn't guarantee a repeat. Every cycle has its own quirks: macro conditions, regulation, dominant narratives. Use the index as a map, not a GPS.

Why pre-configuring alarms makes a difference

The problem with the Altcoin Season Index is simple: it changes slowly. You open the page once a week, see 32, and close the tab. Two months later someone says "we're officially in altseason" and you find out you missed the start of the move.

Alarms fix that blind spot. You set the triggers once and the app pings your phone the instant the value crosses, no need to remember to check.

Setup 01

Confirmation alarm at 75

Set an alarm at ABOVE 75. When it fires, it's the most conservative signal that the market is officially in altcoin season. Good for entering on confirmation.

Setup 02

Early alarm at 60

To get in ahead of the crowd, also set an alarm at ABOVE 60. That level usually indicates the transition is in progress but the broader public hasn't caught on yet.

Setup 03

Bitcoin-dominance alarm

When the index drops BELOW 25, BTC is dominating heavily. It can be the moment to reduce exposure to less liquid altcoins and rotate into BTC or stables.

How to create an Altcoin Season Index alarm in Alarm Crypto

  1. Open the app and tap the + button at the bottom right.
  2. Pick the ALT S. tab at the top of the search modal.
  3. Tap Altcoin Season Index.
  4. Use the 0-100 slider to set the trigger (for example, 75).
  5. Pick "ABOVE" or "BELOW" and confirm.

That's it. Alarm Crypto polls the index in the background and fires a real alarm sound on your phone the exact moment your trigger crosses, even with the app closed.

Frequently asked questions

How often is the Altcoin Season Index updated?

The index is recalculated daily, based on the last 90 days of performance. Changes are usually gradual, but during market transitions the value can swing meaningfully week over week.

Do stablecoins count?

No. Stablecoins (USDT, USDC, DAI, etc.) and BTC-pegged tokens (WBTC, BTCB) are excluded to avoid skewing the result. The focus is on assets that compete with Bitcoin for capital.

Is the index only useful for "buying altcoins"?

No. It's a capital-rotation thermometer. Whether you're long or short, it helps you understand whether the tide favors majors or alts.

Can I use the index as my only decision tool?

We don't recommend it. It's an aggregated, relative indicator: the index can read "Bitcoin Season" while specific altcoins still rip. Combine it with technical analysis of each asset and proper risk management.

Conclusion

The Altcoin Season Index is one of the most useful tools for anyone trading or investing in altcoins. It doesn't tell you when to buy a specific coin, but it tells you whether the macro environment favors altcoins or Bitcoin right now.

Paired with Alarm Crypto alarms, it stops being a page you forget to visit and becomes a direct phone notification at the moments that matter. To round out the picture, also read the post on the Crypto Fear & Greed Index and the Alarm Crypto guide.