Stochastic OscillatorSTOCH
The stochastic oscillator shows where the latest close sits within the recent high–low range, on a scale from 0 to 100.
The stochastic oscillator asks: where did the price close relative to its recent range? A close near the top of the last 14 periods’ range scores near 100; near the bottom, near 0. In rising markets closes tend to cluster near the highs, and in falling markets near the lows, so the indicator tracks momentum. It is popular for timing entries in ranges and pullbacks — and, like all oscillators, it can stay at extremes in strong trends.
- Category
- Indicators and Tools
- Reading time
- 5 min
- Also called
- Stochastic, Stochastics, %K
- Updated
The stochastic oscillator in plain words
Take the highest high and lowest low of the last 14 bars.1 If today’s close is at the very top of that range, %K is 100; at the bottom, 0; halfway, 50.
A smoothed version of %K, called %D, is drawn as a second line.2 Readings above 80 are commonly called overbought and below 20 oversold. See Overbought and Oversold.
How to calculate and read the stochastic, step by step
Find the recent range
Highest high (HH) and lowest low (LL) over the look-back, typically 14 periods.
Calculate %K
%K = (close − LL) ÷ (HH − LL) × 100.
Smooth it
%D is usually a 3-period average of %K. The common “slow stochastic” smooths %K first, giving settings such as 14, 3, 3.
Read the zones
Above 80 is commonly overbought, below 20 oversold — descriptions, not signals.
Watch crossovers
%K crossing above %D from below 20 is a common buy signal in ranges; crossing below from above 80 a sell signal.
Respect the trend
In strong trends the stochastic can stay above 80 or below 20 for long periods. See Trend.
Worked examples
Example 1 — Calculating %K
%KOver 14 days the highest high is $58 and the lowest low $50. Today’s close is $56.
| %K | ($56 − $50) ÷ ($58 − $50) × 100 = 75 |
The close sits three-quarters of the way up the recent range — strong, but not yet in the overbought zone.
Example 2 — A crossover in a range
RangeA stock ranging between $40 and $46 drops to $40.50; the stochastic falls to 12, then %K crosses above %D. A trader buys at $41, stop $39.80, target $45.50.
| Risk | $1.20 |
| Reward | $4.50 |
| Reward-to-risk | 3.75 : 1 |
The stochastic works best in ranges, where the edges and the oscillator agree. See Range.
Example 3 — Stuck at the top
TrendIn a strong uptrend, the stochastic stays above 80 for 12 of 15 sessions as the stock rises 18%.
| Sell signals from crossovers | Several — all premature |
In trends, “overbought” is a sign of strength. Many traders only take stochastic signals in the trend’s direction.
Oscillator zones in practice
Stochastic vs. RSI
| Aspect | Stochastic | RSI |
|---|---|---|
| Measures | Close relative to recent range | Size of gains vs. losses |
| Common zones | 80 / 20 | 70 / 30 |
| Speed | Faster, more signals | Smoother |
| Best use | Ranges and short-term timing | Momentum and divergence |
How traders use the stochastic
Range timing
Buying low readings near support and selling high readings near resistance. See Range Trading.
Pullback entries
In uptrends, a dip to oversold followed by a %K/%D cross up can mark the end of a pullback. See Pullback.
Divergence
Price making new highs while the stochastic does not warns of fading momentum. See Divergence.
Short-term confirmation
Used alongside a trend filter such as a moving average. See Moving Average.
Advantages and disadvantages
Advantages
- Responsive to turning points in ranges.
- Bounded scale makes readings easy to compare.
- Clear crossover signals.
Disadvantages
- Many false signals in trends.
- Very sensitive to settings.
- Fast versions are noisy.
- Overbought/oversold readings can persist.
Going deeper
Read as far as you need. Each level builds on the one before it.
Fast vs. slow
Beginner
The fast stochastic uses raw %K and is very jumpy. Most traders use the slow version, which smooths %K before calculating %D.
Filter by trend
Intermediate
A common rule: in an uptrend (price above a rising 50-day average), only take buy signals from oversold readings; in a downtrend, only sell signals from overbought readings.
Origins and settings
Advanced
The stochastic was popularised by George Lane in the 1950s. Settings such as 5,3,3 or 21,5,5 change its speed; there is no universally correct choice, and optimising settings to past data risks Overfitting.
Common mistakes
Selling every reading above 80
In uptrends, the stochastic can stay high for weeks.
Too many signals
Fast settings on short timeframes generate constant noise.
Ignoring support and resistance
Signals at key levels are more meaningful than signals in the middle of nowhere.
Using it alone
Combine with trend and structure.
Check your understanding
Test yourself before moving on. Each answer comes with an explanation.
Key points to remember
- %K = (close − lowest low) ÷ (highest high − lowest low) × 100.
- %D is a smoothed %K; crossovers generate signals.
- 80/20 are the common overbought/oversold levels.
- Best in ranges; misleading in strong trends.
- Use with a trend filter and key levels.
Frequently asked questions
What are the best stochastic settings?
Is the stochastic better than the RSI?
What does a %K/%D crossover mean?
Further learning
- Relative Strength Index
The other most popular oscillator.
- Overbought and Oversold
What the zones really mean.
- Range
Where the stochastic works best.
- Divergence
A stronger signal than zones alone.
Sources
This article is written in our own words. The sources below support the specific facts, rules and figures marked with a number in the text. Links open the original publisher’s page.
- StockCharts ChartSchool. Stochastic Oscillator (Fast, Slow, and Full) (opens in a new tab) Checked .
- Fidelity. Slow Stochastic (opens in a new tab) Checked .
Read more elsewhere
- Trading Metrics (our sister site): Stochastic Oscillator (opens in a new tab)
Educational content, not financial advice. Examples use hypothetical prices and simplified costs; actual fees, margin rules and regulations vary by broker, market and country. Trading Metrics is our sister site, under the same ownership; we are not affiliated with any other publisher linked above. Last reviewed . Report an error or request a source credit.