Fear and Greed Index: What It Measures and When It Misleads

The crypto fear and greed index is a single number from 0 to 100 that summarises market sentiment for Bitcoin: 0 means "Extreme Fear" and 100 means "Extreme Greed". It misleads when you read it as a signal, because half of it is built from price volatility and momentum. In that case it mostly repeats what the chart already shows.

This guide uses the Alternative.me index, the one most traders mean by that name. It covers what goes into it, how its values looked over the last 90 days, and four checks that keep you from misreading it. The methodology comes from alternative.me and the daily values from its public API, both fetched on 20 Oct 2026.

What the crypto fear and greed index measures

Alternative.me describes it as one number built from "emotions and sentiments from different sources". The current index is for Bitcoin only. Its page says a big part of the index is the volatility of the coin price, and that separate indices for large altcoins were planned.

The page lists the factors and their weights:

• Volatility (25%). Current volatility and maximum drawdowns of Bitcoin, compared with the averages of the last 30 and 90 days. An unusual rise in volatility is read as fear.
• Market momentum and volume (25%). Current volume and momentum against the same 30 and 90 day averages. High buying volume in a rising market is read as greed.
• Social media (15%). Counts of posts and interactions on Bitcoin hashtags. An unusually high interaction rate is read as greed.
• Surveys (15%). Weekly polls run with strawpoll.com, a site Alternative.me says it also owns. The page marks this factor "currently paused".
• Dominance (10%). Bitcoin's share of the total crypto market cap. A rising share is read as fear of speculative altcoins, a falling share as greed.
• Trends (10%). Google Trends data for Bitcoin-related searches, including the change in search volume and related queries.

Two details matter. First, volatility and momentum together carry 50% of the weight, and both are computed from price and volume. Second, the surveys factor is listed at 15% but marked paused, and the page does not say how that weight is handled. The same page also still says Reddit analysis is "not in the live index" and gives a Google Trends example dated 2018, so treat the text as a description of intent, not a live audit of the formula.

How the values looked in the last 90 days

The API at api.alternative.me/fng returns one value per day with a label (Fear, Greed and so on). We pulled the last 90 daily values, from 23 Jul to 20 Oct 2026. The timestamps are at 00:00 UTC.

The shape is lopsided. From 23 Jul to 17 Aug the index stayed between 25 and 34. The low was 25 on 6 Aug, labelled Extreme Fear. Then it moved from 31 on 17 Aug to 72 on 21 Aug. After that it sat mostly between 50 and 78, with a high of 78 on 22 Sep and 55 on 20 Oct.

The labels in that window were uneven too:

Greed took 57 of 90 days and Fear took 25. Extreme Greed appeared once. The value ranges in the table are what we observed in this window, not official thresholds, which we did not find stated on the methodology page.

When it misleads

It follows price more than it leads it

We compared the jump with Binance BTCUSDT daily closes (UTC). BTC closed at 64,532.10 on 17 Aug and 78,338.03 on 21 Aug, a gain of 21.4% in four days. The index went from 31 to 72 over the same days. A volatility and momentum heavy index will do that when price moves fast. It did not warn about the move. It reported it.

The same applies at the other end. On 6 Aug the index hit 25 with BTC at 64,323.61, and on 22 Sep it hit 78 with BTC at 86,208.56. Those are single days from one window, so they show how the index behaves, not that extremes mark turning points. BTC closed at 83,663.66 a week after the 78 reading, 3.0% lower, and the index was still 73.

A level is not a rule

Alternative.me's own assumption is that extreme fear can be a sign investors are too worried and that too much greed means the market is due for a correction. That is a hypothesis, not a measured edge. In our window the index carried a Greed label on 57 of 90 days, and on 29 Sep it still read 73 after the 78 reading. A high number told you the market had been rising, not when it would stop.

It describes Bitcoin, not your coin

The index is for Bitcoin only. Using it to judge an altcoin ignores that the coin may have its own supply events, listings and liquidity. Check the coin's own data on its market page or its coin guide instead.

The inputs are not all equal in quality

Social, search and survey inputs are noisy and one of them is paused. The weights on the page add up to 100%, but a factor that is paused cannot contribute in the way the table suggests. Read the number as a rough summary, not a measurement with decimals.

How to read it in four steps

1. Check the date. The API value is daily at 00:00 UTC. An intraday move will not show until the next update.
2. Look at the direction. A move from 31 to 72 in four days says more than a level of 55. Use the 90-day line, not the single number.
3. Compare it with the chart. If BTC just rallied 20%, a high reading is the rally restated. Ask what else is new, such as funding, open interest or a macro event like the FOMC decision or CPI release.
4. Use it for context, then size the trade yourself. Sentiment can tell you how crowded the mood is. It cannot place your stop. Use the position size calculator and your own levels. More guides are in the Handbook.

FAQ

What is a good Fear and Greed Index number to buy at? There is no number with a proven edge. Alternative.me suggests extreme fear can be a buying opportunity, but it describes this as an assumption. In our 90-day sample the index stayed under 35 for weeks while BTC's daily closes stayed between 62,823.64 and 65,399.99 (Binance BTCUSDT, 23 Jul to 17 Aug).

How often does the Fear and Greed Index update? The API returns one value per day, stamped 00:00 UTC, and the website shows a countdown to the next update.

Does the Fear and Greed Index work for altcoins? Not directly. Alternative.me's index is for Bitcoin. The page says separate indices for large altcoins were planned.

Is the index a price predictor? No. In the window we checked, it moved with price rather than before it. Treat it as a description of recent conditions.