RSI, and the mistake everyone makes with it

Overbought means strong, not expensive. Selling strength because a number crossed 70 is how people short bull markets.

The Relative Strength Index compares the size of recent gains to the size of recent losses and expresses the result between zero and one hundred. Above 70 is conventionally called overbought, below 30 oversold.

The misuse

What it is genuinely useful for

1. Divergence

Price makes a higher high while RSI makes a lower high. The move continued but with less force behind it. This is the strongest signal the indicator produces, and even then it is a warning to tighten risk rather than a reason to reverse.

2. Context across markets

Comparing RSI across a basket tells you whether one coin is stretched relative to its peers or the whole market is. The RSI screener on this site does exactly this for ten major markets at once, with each reading classified automatically.

3. Range trading

Inside a well-established range, oversold and overbought readings near the boundaries are reasonable entries — with a stop just beyond the range, because ranges eventually break.

Practical settings

The default period of 14 is fine and there is little to gain from optimising it. Shorter periods produce more signals and more noise. Higher timeframes give more reliable readings: a daily RSI at 25 means considerably more than a five-minute one.

The rule to remember

RSI answers "how one-sided has recent movement been?" It does not answer "what happens next?" Use it to size and to time entries within a thesis you already have, never as the thesis itself.

How the number is actually built

RSI compares the average size of gains to the average size of losses over a lookback period, conventionally fourteen. The result is squeezed onto a scale from zero to one hundred.

Two consequences follow from that construction, and both are routinely missed:

• It measures the balance of movement, not its size. A market grinding up 0.3% every day for two weeks will read as extremely overbought despite modest total movement.
• It is bounded, but price is not. RSI cannot go above 100, so in a powerful trend it saturates near the top and stops distinguishing between strong and extraordinary. This is precisely why "overbought" persists for weeks in real trends.

Divergence, done properly

Divergence is the most useful signal RSI produces, and the most frequently misapplied. Three rules make it usable:

1. Only compare comparable peaks. The two price highs should be clear, distinct swing highs — not any two points that happen to support your bias.
2. Higher timeframes only. Divergence on a five-minute chart appears constantly and means almost nothing. On a daily chart it is rare and worth attention.
3. It is a warning, not a trigger. Divergence can persist for a long time while price continues. Use it to tighten stops and reduce size, not to enter a reversal against a live trend.

Using RSI across a basket instead of one chart

A single reading tells you about one asset. Ten readings tell you about the market — and that comparison is where the indicator becomes genuinely informative.

If nine of ten major coins read above 70, you are not looking at one stretched asset; you are looking at a stretched market, and the correct response is portfolio-level (reduce size across the board) rather than asset-level. If one coin reads 80 while everything else sits near 50, that one is doing something specific and worth investigating.

Our RSI screener shows exactly this: daily readings for ten major markets side by side with automatic classification, which turns a single-chart indicator into a market-wide read.

Where RSI genuinely earns its place

• Timing entries inside an existing thesis. You already want to be long; a pullback to RSI 40–45 in an uptrend is a better entry than chasing at 75.
• Range trading with defined boundaries. Oversold near range support with a stop just beyond it is a real setup.
• Sizing. Extreme readings justify smaller positions, because the distance to a mean reversion is larger.
• Filtering out bad entries. Refusing to buy at RSI above 75 removes a category of chase trades that reliably lose money.

Notice that none of these use RSI as the reason for the trade. It refines a decision you reached some other way — which is what an indicator is for.

Common questions

What RSI period should I use?

Fourteen, and do not optimise it. Shorter periods produce more signals with more noise; longer ones lag. Any period that only works after tuning is describing the past rather than predicting anything.

Can RSI stay above 70 for a long time?

Yes, for weeks in a genuine trend, and this is the single most important thing to understand about it. Overbought means strong. Traders who short every reading above 70 spend bull markets losing money.

Is RSI useful for crypto specifically?

It behaves the same way, but crypto trends harder than most markets, so saturation at the extremes lasts longer and mean reversion is less reliable. Divergence on high timeframes and cross-market comparison are the two uses that survive.