KDJ K, D and J Lines Explained: Formulas and Meaning
Learn the formulas for the K, D and J lines that make up the KDJ indicator, verified against multiple technical analysis sources.
- 7 min read
- For beginners
- Educational
- Aula 2 de 7
- 1KDJ Indicator Explained: A Beginner's Guide
- 2KDJ K, D and J Lines Explained: Formulas and Meaning
- 3KDJ Crossover Explained: Golden Cross and Death Cross
- 4KDJ Overbought and Oversold Zones
- 5KDJ Divergence: Comparing KDJ to Price
- 6KDJ in Ranging vs Trending Markets: An Important Nuance
- 7The Difference Between KDJ and the Stochastic Oscillator
This lesson explains the three components of KDJ — the K line, D line, and J line — including the underlying RSV calculation they're built from.
These formulas have been verified against multiple technical analysis education sources for consistency.
The Starting Point: RSV (Raw Stochastic Value)
KDJ begins with RSV, calculated as: RSV = [(Close − Lowest Low over N periods) ÷ (Highest High over N periods − Lowest Low over N periods)] × 100. The standard period (N) is 9. RSV expresses where the current close sits within the recent high-low range, on a scale from 0 to 100 — a reading near 100 means the close is near the period's high, and a reading near 0 means it's near the period's low.
The K Line
The K line (the "fast line") is calculated as: K = (2/3) × Previous K value + (1/3) × Today's RSV. This is a smoothed value derived from RSV, generally responding relatively quickly to recent price changes. For the very first calculation, where no previous K value exists, a starting value of 50 is generally used.
The D Line
The D line (the "slow line") is calculated as: D = (2/3) × Previous D value + (1/3) × Today's K value. This applies the same smoothing process to K that K applied to RSV, making D slower-moving and less reactive than K, similar in concept to how a signal line smooths the MACD line (covered in the previous unit).
The J Line
The J line is calculated as: J = 3 × K − 2 × D. Unlike K and D, which are both bounded within 0–100, the J line's formula allows it to extend beyond this range in either direction, amplifying the divergence between K and D to provide a more exaggerated, sensitive reading. This J line is the specific addition that distinguishes KDJ from the traditional Stochastic Oscillator, covered in detail in this unit's final lesson.
Summary
KDJ is built from RSV (measuring where the close sits within its recent high-low range), smoothed into the K line (fast), further smoothed into the D line (slow), with the J line (3K − 2D) amplifying the divergence between K and D and extending beyond the standard 0–100 range that bounds K and D. This J line is the specific feature that distinguishes KDJ from the traditional Stochastic Oscillator.
Frequently Asked Questions
Raw Stochastic Value, calculated as [(Close − Lowest Low) ÷ (Highest High − Lowest Low)] × 100 over a standard period of 9, expressing where the close sits within the recent range.
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