The Altcoin Strength Index, explained

Compared against

104/156/260

weeks — two, three and five years

Base blend

80 / 20

its level vs its gap to trend

Driver cap

±15 pts

the most timing can move the score

Levels drawn

25 / 75

the buy and sell lines on the chart

A weekly score, 0 to 100, that answers one question: are altcoins cheap or expensive against Bitcoin by their own history? Zero is the cheap end, 100 the expensive end. It is built from a single ratio — that one ratio — and nothing else: no dollar prices, no blockchain data, no sentiment.

The name says strength; the scale says risk. This is a valuation gauge, and it points the same way as every other risk chart here — high is the stretched end. A long run of altcoins outrunning Bitcoin lifts the ratio, which lifts its standing against history, which pushes the score toward 100. The strength is what makes the reading a warning.

A dollar-denominated altcoin index answers two questions at once: is the entire crypto market rising, and are altcoins specifically pulling ahead of Bitcoin within it? Those are different questions, and mixing them makes it hard to tell a genuine rotation into altcoins from a rising tide lifting every boat, Bitcoin included.

Measuring altcoins against Bitcoin is the fix: total crypto market cap except Bitcoin, Ethereum, stablecoins and tokenized RWAs, divided by Bitcoin's market cap. The ratio only moves when altcoins gain or lose ground relative to Bitcoin — a broad rally that lifts Bitcoin and altcoins by the same amount leaves it flat.

Only completed weeks count — the week in progress never moves the score. From there, the model has two halves.

1. Where it sits in its own history — rank this week's ratio against the last 104, 156 and 260 weeks — two, three and five years — weighted 20/30/50 toward the longest window. A rank of 70 means the ratio has been lower than this on 70% of those weeks. The five-year view carries half the verdict. The ranking is done on a log scale, so a doubling counts the same whether it happens from a low base or a high one.

2. How far it sits from its own trend — the same ratio measured against its own 104-week trend line, an average that leans on recent weeks, with that gap ranked over 156 weeks. A market can look cheap purely because it has been falling for years; this asks whether the ratio is below its own drifting fair value, not merely low.

3. Base value — 80% of the first, 20% of the second. This is the structural half of the model, and it is the part with the weight.

4. Drivers — three measures asking whether conditions are already turning, each judged against how unusual it is by the standards of the last 52 weeks. The ratio's own acceleration carries 55%: its 4-week pace against its 13-week pace, blended 70/30 with the raw 4-week pace. ETH/BTC carries 30%, built the same way — Ethereum sits outside that ratio, so it is an independent read on appetite for risk. The 13-week growth of combined USDT and USDC market cap carries the last 15%.

5. The score — the base value plus that driver adjustment, held between 0 and 100. The adjustment is capped at 15 points either way, however extreme the drivers get. Improving drivers lower the score; deteriorating drivers raise it.

The cap is the design. The buy and sell zones are 25 points deep and the drivers get 15, so they can move a reading around inside its zone or just past the edge of it, never from one end of the scale to the other. A base value of 90 stays at or above 75 whatever the drivers say. They can turn "expensive" into "expensive and rolling over"; they cannot turn it into "cheap." This is a valuation chart first, and the timing half is deliberately the smaller one.

The same adjustment also splits the labels. At 25 or below, a supportive adjustment reads as BUY TRIGGER and an unsupportive one as CHEAP / EARLY; at 75 or above, deteriorating drivers read as SELL / DEFENSIVE and a move still running as EXPENSIVE / RISING. Ten labels in total, from DEEP VALUE at 15 and below to DEEP RISK at 85 and above, and the same level can carry two of them depending on which way conditions are moving.

Zero is the interesting end. The word "strength" in the name is the only thing on this page suggesting otherwise — the scale itself runs cold where altcoins are cheap and red where they are expensive, exactly like every other risk gauge here.

The line carries its own verdict. It is coloured by the model's state on the same heat scale as our other charts: deep blue below 15, blue and cyan from 15 to 25, amber across the wide 25–75 middle, orange and red above 75. Two dashed lines mark the levels that matter — blue at 25, red at 75 — with the zones below 25 and above 75 shaded to match.

Hover to see the split. The tooltip shows the score alongside the underlying valuation and the driver adjustment that produced it, so a reading of 70 is legible: valuation at 70 with neutral drivers is a different market from valuation at 80 with drivers pulling 10 points off it.

The white line is the ratio itself. It is plotted on its own right-hand axis, with a choice of log or linear scale, so you can see the input the whole calculation comes from. The score axis is fixed at 0–100 and the chart always shows the full weekly history.

A ranking cannot really be wrong about where the ratio sits — only about whether that is worth acting on. Its limits are structural. The reference window moves with the market, so "cheap" is always cheap by recent standards. And there is no dollar context at all: altcoins can be at 10 on this scale and still falling in price, because Bitcoin is falling faster.

Read it as a weekly allocation filter for one question: lean the portfolio further toward altcoins, or back toward Bitcoin? It does not pick coins, does not forecast, and says nothing about how long a reading will hold. A score of 20 is a statement about the odds on offer, not a promise about next quarter.

The other altcoin-versus-Bitcoin read on this site is the Altcoin Season Index, a daily 0–100 series published by CoinGlass and charted here as it comes. Neither one feeds the other: this model reads the daily stored Altcoins/BTC series plus CoinGecko drivers, and the Altcoin Season Index reads the CoinGlass series and nothing else. Two different questions, worth reading side by side and worth not confusing.

Others in market structure — How much borrowed money is in the market, which way bets are leaning, and where money is moving.

• Bull Market ProgressHow far roughly thirty cycle-peak indicators have travelled toward their historical top readings.
• Funding RateWhat leveraged traders pay to hold their positions — the cost of crowd consensus.
• Open InterestHow much leverage is outstanding across futures venues, and which exchanges hold it.
• LiquidationsWhere leveraged positions were forcibly closed, long against short.
• Altcoin Season IndexCoinGlass’s published 0–100 rotation index, with 80 and above marking Altcoin Season and 20 and below Bitcoin Season.

Every indicator we track — the full glossary.