# RSI screener guide for NSE stocks

> Why most RSI-below-30 scans return falling knives, the trend filter that fixes them, the RSI levels that matter in trending stocks, and four ready-made NSE scans.

Canonical: https://patternsradar.com/blog/rsi-screener-guide

Published 2026-08-15. Related scans: https://patternsradar.com/screener/rsi-oversold-turn.md, https://patternsradar.com/screener/rsi-overbought.md, https://patternsradar.com/screener/rsi-50-reclaim.md, https://patternsradar.com/screener/stoch-rsi-oversold.md, https://patternsradar.com/screener/pullback-in-uptrend.md

"RSI below 30" is probably the most-run scan in retail screening, and run bare, it is one of the worst. The list it returns is dominated by stocks that are oversold because they are *dying* — downtrends make low RSI readings constantly, and buying them is catching knives with a number attached.

The fix is one condition. But it helps to know what RSI actually measures first.

## What RSI is

The Relative Strength Index compares the average size of recent up-days to recent down-days over a window (almost always 14 sessions) and squashes the ratio to 0–100. Above 70 means the recent tape has been one-sidedly bullish; below 30, one-sidedly sellers. It measures **one-sidedness, not value** — nothing about RSI says a stock is cheap, only that its recent sessions have leaned hard one way.

One-sidedness tends to resolve. That reversion is the entire edge, and it only pays when the larger context says the resolution should be *upward*.

## The one-condition fix

```
where rsi(14) < 30 and close > sma(200)
```

The 200-day filter splits the oversold list into its two populations. Oversold **above** the 200-day is a healthy stock having a bad fortnight — an owner base in profit, defending. Oversold **below** it is a downtrend doing what downtrends do; it can stay below RSI 30 for months. Same reading, opposite trades.

The prebuilt version adds one more refinement — it waits for the *turn* rather than buying the reading:

```
where rsi(14) crossed above 30 within 3 bars and close > sma(200)
```

Crossing back above 30 is the first measurable evidence the selling stopped. Run it: **[RSI oversold, turning up](https://patternsradar.com/screener/rsi-oversold-turn.md)**.

## The level nobody screens for: 50

In an actual uptrend, RSI rarely reaches 30 at all — pullbacks bottom near 40–45 and turn. Waiting for the textbook 30 means missing every routine dip in every strong stock. Two scans cover the trending case:

- **[RSI reclaiming 50](https://patternsradar.com/screener/rsi-50-reclaim.md)** — the midline cross is the earlier, more frequent buy signal inside uptrends; it marks "pullback over" rather than "washout over."
- **[Pullback in an uptrend](https://patternsradar.com/screener/pullback-in-uptrend.md)** — RSI under 40 with the 200-day intact. Rare by construction, which is why the list is short and worth reading on the days it isn't empty.

For the hair-trigger version there is **[Stochastic RSI oversold](https://patternsradar.com/screener/stoch-rsi-oversold.md)** — the stochastic formula applied to RSI itself, reaching extremes on dips plain RSI barely registers. It fires often; treat it as a shortlist builder, not a signal.

## The other side

RSI above 70 in a stock you hold is not automatically a sell — strong trends spend weeks above 70, and "overbought" is often just "working." What it *is*: a reason to move a stop up, and in weak stocks, a fade candidate. **[RSI overbought](https://patternsradar.com/screener/rsi-overbought.md)** keeps the strong-trend context (`close > sma(50)`) so the list reads as "extended," not "doomed." The wider [reversal family](https://patternsradar.com/scans/reversals.md) has the CCI, Williams %R and stochastic variants of both sides.

## Check the levels against reality

Every threshold in this guide — 30, 40, 50, 70 — is convention, and convention is checkable. Each scan page carries a hit-rate replay across the past year of NSE sessions: how often did the signal resolve upward, over what horizon, at what cost when it failed? Ten minutes of replay on [the oversold-turn scan](https://patternsradar.com/screener/rsi-oversold-turn.md) versus a bare RSI-below-30 query will teach you more about RSI on Indian stocks than any tutorial — including this one.