Indicators
2 min read
What Is RSI? A Complete Guide to the Relative Strength Index
The momentum oscillator every crypto trader should understand — what it measures, how it's calculated, and where it can mislead you.
By
RSI Monitor Research
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updated
What RSI actually measures
The Relative Strength Index (RSI) is a momentum oscillator that compares the magnitude of recent gains to recent losses over a fixed lookback period (14 periods by default). It outputs a single value between 0 and 100. Traditionally, readings above 70 are considered overbought, while readings below 30 are considered oversold.
RSI does not measure trend direction or intrinsic value — it measures the speed and strength of recent price movement. In a strong uptrend, an asset can remain overbought for weeks.
The formula
RSI = 100 − [100 ÷ (1 + RS)], where RS = average gain ÷ average loss over the selected lookback period. RSI Monitor uses Wilder's smoothing method, which is effectively an exponential moving average with α = 1 / period. This is the original method introduced by J. Welles Wilder Jr. in 1978 and the default implementation used by TradingView and most professional charting platforms.
How to interpret RSI
- RSI > 70: Buying pressure has been unusually strong recently. In downtrends, this often marks the end of a relief rally. In strong uptrends, however, RSI can stay elevated for an extended period.
- RSI < 30: Selling pressure has been unusually strong recently. In uptrends, this may present a dip-buying opportunity. In downtrends, it can signal continued weakness rather than a reversal.
- Divergence: If price makes a new high while RSI fails to do the same, momentum may be weakening even though price is still rising.
What beginners often get wrong
Treating RSI as a simple binary signal ("oversold = buy") is one of the most common mistakes new traders make. RSI works best in ranging markets, during momentum divergences, and as a confirmation tool — not as a standalone entry signal.