Harmonic patterns
Harmonic patterns: what XABCD and Fibonacci measurements mean
A harmonic pattern compares the proportions of successive price swings. ChartPro checks five confirmed turns, labelled X, A, B, C, and D, for four supported pattern families: Gartley, Bat, Butterfly, and Crab. A matching shape describes historical price geometry; it does not establish what happens next.
What do X, A, B, C, and D stand for?
They identify five alternating turning points in chronological order. XA is the first leg; AB, BC, and CD follow. The detector compares the sizes of those legs, rather than accepting every zigzag with five corners. A shape can resemble a harmonic visually and still fail the ratio checks.
Fibonacci measurements are used to compare retracements and extensions. The names distinguish different proportional structures. Other tools can use different swing rules and tolerances, so matching the name alone does not mean two implementations measured the same turns.
A simple measurement example
This is hypothetical arithmetic, not a historical chart or a market forecast. Suppose X is 100 and A is 200: XA spans 100 price units. If B is 138.2, AB spans 61.8 units, so AB/XA is 0.618. That passes one Gartley measurement in ChartPro. It does not establish a Gartley by itself: C, D, the other leg ratios, their order, and the confirmed swings must qualify too.
Which patterns does ChartPro check?
The following are ChartPro's implemented measurements. Exact ratio targets allow a small tolerance; the remaining legs must also pass their own checks.
- Gartley: AB/XA near 0.618 and AD/XA near 0.786.
- Bat: AB/XA between 0.382 and 0.500, with AD/XA near 0.886.
- Butterfly: AB/XA near 0.786 and AD/XA near 1.270; D extends beyond X.
- Crab: AB/XA between 0.382 and 0.618, with AD/XA near 1.618; D extends beyond X.
For each family, the engine also checks BC relative to AB, CD relative to BC, and the relationship between CD and AB. It measures both orientations. The app currently does not offer every named harmonic family; a general XABCD drawing is not automatically one of the four supported patterns.
How to inspect a harmonic in ChartPro
- Open ChartPro, search for an instrument, and confirm the listing.
- Choose the candle interval: 1D, 1W, or 1M.
- If the history contains a qualifying match, inspect the separate HARMONIC row and its measured ratios.
- Use Show harmonic overlay to inspect the XABCD geometry on the chart. Use Show chart patterns to return to the classic-pattern view.
Classic patterns such as wedges and triangles retain their own analysis and default overlay. A harmonic match does not replace the classic pattern label. This matters when the same history contains, for example, a wedge and a separate five-turn ratio structure.
Why some charts show no harmonic
The detector requires confirmed, consecutive swing points and checks each candidate against its rules. The default swing detector needs later bars on both sides of a turning point, including five bars after D to confirm that turn. It therefore does not label a projected D before it exists. Several recent candles can pass before a candidate is confirmed.
Missing matches are expected. The ratios may fail, there may be too little history, or a match may be too old for the current display ranking. ChartPro ranks harmonic matches separately and displays the leading qualifying result, rather than marking every possible five-turn sequence.
Why the pattern changes with timeframe
Hourly and weekly charts contain different sequences of swings. A pattern found among hourly turns can disappear when those movements are summarized in weekly candles. Changing timeframe makes ChartPro summarize its saved daily bars and recalculate the analysis. Read the timeframe guide before comparing the same company across intervals.
What a match does not establish
A ratio fit is not an outcome probability or a success percentage. Confirmed historical geometry does not guarantee a reversal, and a changing newest candle can affect what the available history shows. Check the measured turns, candle timestamp, nearby support and resistance, and data limitations before interpreting a label.
Try harmonic pattern detection in ChartPro and inspect the measurements on your selected instrument. Both Monthly and Annual include the feature alongside daily, weekly and monthly charts.