Technical & Chart AnalysisStochasticsStochastic
Stochastic Oscillator
An oscillator showing where the close sits within the recent high-low range, plotted as %K and %D on a 0 to 100 scale.
What Stochastic Oscillator means
The stochastic oscillator, devised by George Lane, measures where the current close sits within the high-low range of a lookback period. Raw %K is the close minus the lowest low, divided by the highest high minus the lowest low, multiplied by 100. In the standard 14/3/3 configuration that raw value is smoothed over three periods to give %K, and %D is a further three-period average of %K. The underlying idea is that closes cluster near the top of the range while momentum is strong and near the bottom when it is weak.
Traders use crossovers of %K through %D, particularly when they occur outside the 80 and 20 bands, plus divergence against price at swing extremes. Slow and full variants differ only in how much smoothing is applied. The familiar limitation is shared with all bounded oscillators: because the indicator is scaled to a recent range, it saturates near 100 in a strong uptrend and stays there, so treating 80 as an automatic sell signal produces a long sequence of losses against a persistent trend.
Worked example
With a 14-period EUR/USD high of 1.0900, a low of 1.0800 and a close of 1.0885, raw %K is 85; if %D sits at 79 and both are above 80, the pair is in overbought territory but not necessarily turning.
Related terms
- OscillatorAn indicator that fluctuates around a centre line or within fixed bounds, used mainly to gauge momentum extremes.
- OverboughtA condition in which an oscillator sits at a high extreme after a rapid advance, indicating stretched momentum rather than a sell signal.
- OversoldA condition in which an oscillator sits at a low extreme after a rapid decline, indicating stretched momentum rather than a buy signal.
- DivergenceA disagreement between price and an indicator, where one makes a new extreme that the other fails to confirm.
- RSI (Relative Strength Index)A momentum oscillator that measures the speed and magnitude of recent price changes on a 0 to 100 scale.
Frequently asked questions
What does Stochastic Oscillator mean in forex trading?
An oscillator showing where the close sits within the recent high-low range, plotted as %K and %D on a 0 to 100 scale.
How does Stochastic Oscillator work in practice?
Traders use crossovers of %K through %D, particularly when they occur outside the 80 and 20 bands, plus divergence against price at swing extremes. Slow and full variants differ only in how much smoothing is applied. The familiar limitation is shared with all bounded oscillators: because the indicator is scaled to a recent range, it saturates near 100 in a strong uptrend and stays there, so treating 80 as an automatic sell signal produces a long sequence of losses against a persistent trend.
What is an example of Stochastic Oscillator?
With a 14-period EUR/USD high of 1.0900, a low of 1.0800 and a close of 1.0885, raw %K is 85; if %D sits at 79 and both are above 80, the pair is in overbought territory but not necessarily turning.
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