The stochastic oscillator is a momentum indicator that compares the current close with the high-low range of the last n candles and expresses it from 0 to 100. The classic reading treats values above 80 as overbought and below 20 as oversold, but in a strong trend it can stay in those zones for a long time, so it is not a buy or sell signal on its own. This guide explains the formula, the usual settings, how to read crossovers and divergences, and its limits.
How it is calculated
%K = (Current close − Lowest low of n candles) ÷ (Highest high of n candles − Lowest low of n candles) × 100
%D is a moving average of %K (normally 3 periods). The usual setting is 14, 3, 3: 14 candles for the range, 3 for smoothing %K and 3 for %D. Some platforms, such as MetaTrader 5 and TradingView, use these defaults, but check them on your own chart.
How to read it
| Reading | What it indicates | Caution |
|---|---|---|
| %K > 80 | Close near the top of the recent range | In an uptrend it can stay high |
| %K < 20 | Close near the bottom of the recent range | In a downtrend it can stay low |
| %K crosses above %D | Improving momentum | More reliable in the low zone and with context |
| %K crosses below %D | Weakening momentum | More reliable in the high zone and with context |
| Divergence | Price makes an extreme that the oscillator does not confirm | It is a warning, not an entry |
Illustrative example (made-up figures for teaching purposes)
Suppose that over the last 14 candles the high is 110, the low is 100 and the current close is 108. %K = (108 − 100) ÷ (110 − 100) × 100 = 80. The close sits in the top 80% of the range. If the next candle closes at 105, %K drops to 50: the oscillator changes a lot even though price only fell 3 points. This example does not correspond to any real market.
Limits and common mistakes
- Trading every crossover: in sideways ranges it produces many false signals, and in trends it creates entries against the move.
- Ignoring the timeframe: what is overbought on a 5-minute chart can be neutral on a 4-hour chart.
- Using it without structure: combine it with support and resistance and the reading of candlestick patterns.
- Not defining invalidation or risk: apply the 1% rule.
Stochastic, RSI and MACD
The stochastic measures where price closes within its range; the RSI measures the relative strength of up moves versus down moves; the MACD compares moving averages. Using all three without a plan only adds noise, because they all derive from the same price.
How AIM can help
AIM helps interpret the screenshot and organize scenarios; it does not predict price or guarantee results.
Frequently asked questions
What is the best stochastic setting?
There is no single best one. 14,3,3 is the most widespread; shorter periods react faster and add noise. Test it on a demo account.
Slow or fast stochastic?
The slow version applies extra smoothing to %K and gives fewer false crossovers; the fast one is more sensitive.
Are 80 and 20 mandatory levels?
They are conventions. Some traders use 70/30 or other levels depending on the asset; none guarantees a reversal.
Does it work for forex, gold and indices?
It is calculated the same way on any priced asset, but how useful it is depends on each market's trend and volatility.
Educational information from AIMPATFX, not financial advice. Trading currencies and CFDs carries a high risk of loss.
