RSI (Relative Strength Index)
RSI is Wilder's relative strength index, a momentum oscillator scaled 0 to 100 that measures how one-sided recent sessions have been by comparing the average size of up-closes to down-closes.
RSI splits the last fourteen sessions into gains and losses, smooths each with Wilder's own moving average, and expresses the ratio on a 0–100 scale. A reading of 70 means recent up-days have overwhelmed down-days; 30 means the reverse. Because the smoothing carries long memory, RSI moves deliberately. One big session shifts it. It takes a run of one-sided sessions to pin it at an extreme.
The textbook levels are 70 overbought and 30 oversold, but on daily NSE bars the more useful readings are contextual. In a genuine uptrend RSI rarely touches 30 at all. Pullbacks bottom near 40 and the reclaim of 50 marks the dip ending, which is why RSI-crossing-50 scans exist alongside the oversold ones. The standard pairing is a long-term trend filter: RSI under 40 above the 200-day average is a pullback, and the same reading below it is a decline in progress.
The way RSI hurts people is simple. Oversold is not a floor and overbought is not a ceiling. A stock in real trouble can hold RSI under 30 for months while it halves; a strong trend can ride above 70 for weeks. The reading describes the recent past. It says the move has been one-sided and says nothing about whether it must stop. Waiting for the cross back through a level at least asks for evidence.
Its nearest sibling is MFI, which runs the same construction weighted by money traded. RSI counts the sessions; MFI weighs them. The stochastic measures something different despite the similar scale: where the close sits in the recent range rather than how large the moves were.
In Sift
Written as rsi(14). A working scan — stocks whose RSI reclaimed 30 in the last three sessions while holding the 200-day average:
where rsi(14) crossed above 30 within 3 bars and close > sma(200)0
of the 500 most-traded NSE stocks match today, as of 25 Sept 2026
Scans that use it
Prebuilt scans in the library whose query reads this value — each with a hit-rate replay over the last 250 sessions.
RSI oversold turning up
RSI back above 30 within the last three sessions, in a stock still holding its 200-day average.
RSI overbought
RSI over 70 in a stock still above its 50-day average. Stretched, and worth knowing either way.
RSI reclaiming 50
RSI crossing back above its midline in a stock that never lost its long-term trend.
RSI bullish divergence
Price near a two-month low while RSI sits at least three points above where it was a month ago. The selling is running out of momentum before it runs out of price.
RSI bearish divergence
Price near a two-month high while RSI reads three points below its level of a month ago.
CCI overbought
CCI above +100 with RSI over 65. Two oscillators saying the same thing at once.
Williams %R overbought
Closing in the top fifth of its two-week range with RSI above 70.
Near a five-year low
Within 5% of the lowest low in five years with RSI under 35. The most abandoned names on the exchange, for a reversal hunt.
Fifteen sessions under the 20-day
Fifteen or more unbroken closes below the 20-day average, RSI under 35. A slump old enough to be exhausted.
Strong but not overbought
Up more than 20% in three months with RSI between 45 and 65, above the 50-day average. Room to run without chasing.
Strong directional trend
ADX above 30, +DI over −DI, the averages stacked, RSI still under 70.
Rate of change leaders
Rate of change above 10 with RSI still under 70, price above the 50-day average.
Pullback in an uptrend
RSI under 40 in a stock still above its 200-day average.
Seven up days in ten
Seven of the last ten sessions closed above their open, in a stock above its 50-day with RSI under 70.
Longest streaks above the 21 EMA
Twenty or more consecutive closes above the 21-day EMA, longest streak first.
Hammer while oversold
A long lower wick with RSI under 40.
Shooting star after a run
A long upper wick with RSI above 60. Buyers tried and could not hold it.
Bullish harami
A small up-day sitting entirely inside the previous session's big down-candle, with RSI already under 45, which is what separates a pause worth watching from a pause in the middle of nothing.
Bearish harami
A hesitation candle inside a big up-day, with RSI above 55.
Large-cap pullback
Market cap above ₹20,000 crore with RSI under 40. Size doing the quality filtering.
IT stocks in an uptrend
Information Technology names above their 200-day average with RSI over 55.
Common questions
What is a good RSI level for buying?
Context does most of the work, though the textbook answer is below 30. In trending stocks pullbacks bottom near RSI 40, and RSI 35 above a rising 200-day average is a very different situation from RSI 35 in a downtrend. The hit-rate replay on each scan page shows how a given level has actually resolved on NSE history: close-to-close, no costs or slippage, on the universe as of today.
Can RSI stay overbought for a long time?
Yes, and in the strongest stocks it routinely does. An established uptrend can hold RSI above 70 for weeks while price keeps climbing, which is why selling every overbought print exits the best trends early. Overbought describes a recent past that has been one-sided. It sets no deadline.
Why is 14 the standard RSI period?
Wilder used 14 in his 1978 book and the default stuck. Shorter periods make RSI touch its extremes more often; longer ones smooth it toward the midline. Fourteen is a convention with decades of shared usage behind it, and that itself has value, because the levels everyone watches are the ones behaviour anchors to.