Momentum oscillator

RSIRelative Strength Index

Q: What is a good RSI period setting?

14 is the original default and remains the most common. Shorter periods (7, 9) react faster but produce more false signals. Longer periods (21, 28) smooth out noise but lag more. Stick with 14 unless you have a specific strategic reason to change it.

Q: Does RSI work better on certain timeframes?

RSI is most reliable on the 4H and Daily charts. On the 1m and 5m it generates too many false signals to be useful as a standalone indicator. Most professional traders use Daily RSI for bias and 4H RSI for entry timing.

Q: What is RSI divergence?

Divergence happens when price and RSI move in opposite directions. Bearish divergence: price makes a higher high while RSI makes a lower high. Bullish divergence: price makes a lower low while RSI makes a higher low. Most reliable when it lines up with horizontal support or resistance.

Q: Can RSI stay overbought for a long time?

Yes. In strong uptrends, RSI can stay above 70 for weeks. Shorting purely because RSI is above 70 in a trending market is one of the most common amateur losses. RSI overbought/oversold readings require additional confirmation (divergence, structure, news catalyst).

Q: What is the difference between RSI and Stochastic?

Both are momentum oscillators on a 0-100 scale. RSI uses average gains versus average losses. Stochastic compares the current close to the high-low range over the lookback period. Stochastic reacts faster to price changes; RSI is smoother. Many traders use them together as a confirmation pair.

RSI (Relative Strength Index) measures the speed and magnitude of recent price changes on a 0-100 scale. Above 70 suggests overbought, below 30 oversold. The professional use of RSI is divergence, not overbought/oversold signals.

14 candles

Default period

0 to 100

Range

> 70 / < 30

Signal levels

Spotting divergence + overextended moves

Best use

What is RSI?

The Relative Strength Index is a momentum oscillator invented by J. Welles Wilder Jr. in 1978. It plots a single line on a 0-100 scale, derived from the average gain versus average loss over a lookback period (default: 14 candles).

Readings above 70 are commonly called overbought; below 30, oversold. The threshold labels are misleading: in strong trends, RSI can stay above 70 (or below 30) for weeks. The signal value of RSI is not the absolute reading but how price and the indicator move relative to each other.

Category: Momentum oscillator
Default settings: 14 candles
Signal range: 0 to 100
Introduced by: J. Welles Wilder Jr., 1978

How RSI works

RSI is calculated in two steps. First, average gains and average losses are computed over the lookback period using Wilder's smoothing (exponentially-weighted moving average). Second, the ratio (Avg Gain / Avg Loss) is plugged into:

RSI = 100 - (100 / (1 + RS))

The output bounds the indicator between 0 and 100. As price rises consistently, average gain dominates and RSI climbs. As price falls, average loss dominates and RSI drops. The 14-period default reflects roughly two weeks of trading; shorter periods (7) react faster but produce more false signals.

How to use RSI

Three practical uses, ranked by reliability.

1. Bearish divergence at resistance: Price makes a higher high; RSI makes a lower high. Combined with a real horizontal resistance level, this is a high-probability short signal. Bullish divergence at support is the inverse.

2. Centerline crosses: RSI crossing back above 50 from below confirms momentum shift in trend-following setups. Most useful on the 4H + Daily, not intraday.

3. Failure swings: RSI peaks above 70, pulls back, fails to reclaim the prior high. Often a more reliable reversal signal than divergence alone.

Skip the 'sell at 70, buy at 30' approach. It loses money in trends. Use RSI for divergence and structure, not absolute levels.

Want more practical context? Look up unfamiliar terms in the forex glossary, or see how indicators stack on real charts in the trading blog.

RSI FAQ

What is a good RSI period setting?

14 is the original default and remains the most common. Shorter periods (7, 9) react faster but produce more false signals. Longer periods (21, 28) smooth out noise but lag more. Stick with 14 unless you have a specific strategic reason to change it.

Does RSI work better on certain timeframes?

RSI is most reliable on the 4H and Daily charts. On the 1m and 5m it generates too many false signals to be useful as a standalone indicator. Most professional traders use Daily RSI for bias and 4H RSI for entry timing.

What is RSI divergence?

Divergence happens when price and RSI move in opposite directions. Bearish divergence: price makes a higher high while RSI makes a lower high. Bullish divergence: price makes a lower low while RSI makes a higher low. Most reliable when it lines up with horizontal support or resistance.

Can RSI stay overbought for a long time?

Yes. In strong uptrends, RSI can stay above 70 for weeks. Shorting purely because RSI is above 70 in a trending market is one of the most common amateur losses. RSI overbought/oversold readings require additional confirmation (divergence, structure, news catalyst).

What is the difference between RSI and Stochastic?

Both are momentum oscillators on a 0-100 scale. RSI uses average gains versus average losses. Stochastic compares the current close to the high-low range over the lookback period. Stochastic reacts faster to price changes; RSI is smoother. Many traders use them together as a confirmation pair.

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