Guide · Markets
What Is RSI (Relative Strength Index)?
A single number between 0 and 100 that tries to answer one question: has this asset moved too far, too fast, in one direction?
The Relative Strength Index (RSI) is a momentum indicator that measures the speed and magnitude of recent price changes on a scale of 0 to 100, based on the ratio of average recent gains to average recent losses over a set period (commonly 14 days).
The most common way it's used is to flag potentially overextended conditions: a reading above 70 is traditionally read as "overbought" — the asset has risen quickly enough that a pause or pullback becomes more likely — while a reading below 30 is read as "oversold," suggesting a decline may have moved further than the underlying situation justifies.
Those thresholds are a starting heuristic, not a rule: a strong, genuine trend can push RSI above 70 and simply stay there for an extended stretch, with price continuing higher the whole time. Treating "overbought" as an automatic sell signal, rather than as one input among several, is a common way newer traders get caught fighting a trend that has real momentum behind it.
RSI is calculated automatically on Trade2Spike's charting tools, making it easy to watch how it behaves around real overbought and oversold readings on live crypto and stock data — a better way to build a feel for its limits than reading about the number in the abstract.