Harmonic patterns are 5-point price patterns (X, A, B, C, D) where each leg’s length is a specific Fibonacci ratio of the previous leg. Scott Carney systematised them in the 1990s and the framework has held up remarkably well — when a valid pattern completes, the D-point reversal has one of the higher hit rates of any technical setup.
The catch: identifying valid patterns by hand is tedious. You need to draw the legs, measure the ratios, check them against pattern definitions, decide which one fits. This auto-scanner handles all of that and only draws patterns that meet the strict ratio definitions. Below is exactly how to use it.
What is a Harmonic Pattern?
A harmonic pattern is a 5-point structure (XABCD) defined by Fibonacci ratios between the legs:
- Gartley — AB/XA = 0.618, BC/AB = 0.382-0.886, CD/BC = 1.13-1.618
- Bat — AB/XA = 0.382-0.5, BC/AB = 0.382-0.886, CD/BC = 1.618-2.618
- Butterfly — AB/XA = 0.786, BC/AB = 0.382-0.886, CD/BC = 1.618-2.24
- Crab — AB/XA = 0.382-0.618, BC/AB = 0.382-0.886, CD/BC = 2.24-3.618
The D-point is the “Potential Reversal Zone” (PRZ). When price reaches D, the harmonic logic predicts a reversal back toward C (or further). Each pattern has its own D-completion ratio — the Crab is the most extended (CD/BC up to 3.618), making its PRZ furthest from price origin.
The mathematical basis is debatable. The empirical reality on EURUSD H1 is that valid harmonic patterns produce reactions at the D-point with hit rates in the 55-65% range — not magic, but tradable with proper risk management.
How Harmonic Patterns Work on MT4
Our FOB_HarmonicPatterns.ex4 scans the last 200 bars (configurable), identifies alternating swing pivots (high-low-high-low-high or vice versa), and tests each 5-point sequence against the four pattern definitions. Valid patterns are drawn with the XABCD legs as connected lines and a labelled name.
Three patterns matter for forex traders.
The first is D-point reversal entry. The cleanest harmonic setup. When a valid pattern completes at D, enter against the direction of the CD leg (long if D is at a low, short if D is at a high). Stop loss beyond D; take profit at C or further.
The second is Crab pattern primacy. Crab patterns extend furthest (CD/BC up to 3.618). Their PRZ is in extreme territory where price is unlikely to keep extending — the reversal probability is statistically highest of the four.
The third is multi-timeframe confluence. A harmonic pattern’s D-point that aligns with a higher-timeframe S/R level (Fibonacci 61.8, structural pivot, supply zone) is exponentially stronger. Confluence > pattern alone.
Key Features
- Custom MT4 indicator (FOB_HarmonicPatterns.ex4)
- Auto-detection of Gartley, Bat, Butterfly, Crab
- XABCD legs drawn as connected lines
- Pattern name labelled at D-point
- Configurable lookback (default 200 bars)
- Configurable swing-bars filter (default 5)
- Configurable Fibonacci ratio tolerance (default 5%)
- Bullish (D = swing low) / bearish (D = swing high) detection
Best Settings for Harmonic Pattern Indicator
The defaults work for most pairs.
| Use Case | Lookback | Swing Bars | Ratio Tolerance |
|---|---|---|---|
| Day Trading | 200 | 5 | 0.05 (5%) |
| Swing | 300 | 7 | 0.07 (7%) |
| Position | 500 | 10 | 0.07 (7%) |
Recommended starting point: H1 EURUSD with 200-bar lookback, 5-bar swings, 5% ratio tolerance.
Pros and Cons
| Pros | Cons |
|---|---|
| D-point reversals have 55-65% hit rate on majors with proper filters | Custom install required — not built into MT4 |
| Auto-detection eliminates the leg-ratio math | Strict ratio definitions = patterns are rare (1-3 per week per major pair on H1) |
| Mathematically precise — no subjective interpretation | Best on H1+ — too few valid patterns on lower timeframes |
| Pairs naturally with Fibonacci levels for confluence | Requires patience — the indicator may show no patterns for days |
How to Install Harmonic Pattern Indicator on MT4
The Harmonic Pattern indicator is custom. See install custom indicators on MT4.
Step 1: Download FOB_HarmonicPatterns.ex4 from the form below.
Step 2: MT4 > File > Open Data Folder > MQL4 > Indicators. Drop the .ex4 in.
Step 3: Restart MT4 (or refresh Navigator).
Step 4: Drag FOB_HarmonicPatterns onto your H1 chart with default settings.
Step 5: Save as a chart template (“Harmonic-H1”) for one-click reuse.
Trading Strategy: D-Point Reversal
The cleanest harmonic strategy. Best on H1 EURUSD, GBPUSD, gold.
Setup: FOB_HarmonicPatterns + structural S/R for confluence.
Long Entry (bullish pattern):
1. The indicator draws a valid pattern (Gartley/Bat/Butterfly/Crab) with D at a swing low
2. Confirm D-point coincides with a higher-timeframe support level (Fib, structural low)
3. Wait for a bullish rejection candle at the D-point (pin bar, engulfing)
4. Enter long on rejection candle close
5. Stop loss 5-15 pips below D (depending on ATR)
6. Take profit at C-point (typical 1.5-3R)
Short Entry (bearish pattern):
1. Pattern with D at a swing high
2. D-point coincides with HTF resistance
3. Bearish rejection candle at D
4. Enter short on rejection close
5. Stop loss above D
6. Take profit at C-point
The discipline that matters: only trade harmonics with HTF confluence. A valid pattern in isolation has middling win rate; the same pattern at a major Fib level or supply zone has notably higher edge.
Harmonic Patterns vs Fibonacci
Both Fibonacci-derived. Different scope.
| Feature | Harmonic Patterns | Fibonacci Retracement |
|---|---|---|
| Structure | 5-point XABCD | 2-point swing high/low |
| Use | D-point reversal entries | Pullback entries during trends |
| Frequency | 1-3 valid patterns per week per pair | New levels with every swing |
Verdict: Use harmonics for occasional high-edge reversal trades; use Fibs for everyday trend pullbacks. They overlap in mathematical basis but answer different trading questions.
Frequently Asked Questions
Is the Harmonic Pattern indicator free?
Yes. Our FOB_HarmonicPatterns.ex4 is free below. Premium harmonic scanners cost $100-300.
Does the indicator repaint?
Patterns are confirmed only after the swing-bars filter completes (5 bars after D-point). Once confirmed, the pattern is locked.
Which harmonic pattern has the best hit rate?
Crab. Its extended D-point (CD/BC up to 3.618) puts price in extreme territory where reversal probability is statistically highest.
Best timeframe for harmonics?
H1 and H4. Lower timeframes have too few valid patterns to be useful; daily harmonics are excellent for swing trades.
Can I use this on MT5?
Yes. Our enhanced version supports both platforms.
Download Harmonic Pattern Indicator for MT4 – Free
Harmonic detection isn’t built into MT4. Our free FOB_HarmonicPatterns.ex4 gives you:
- Auto-detection of Gartley, Bat, Butterfly, Crab
- XABCD legs drawn as connected lines
- Pattern name labelled at D-point
- Configurable ratio tolerance for less-strict matching
- Bullish + bearish detection
Platform: MT4 (Build 1000+)
File type: .ex4
File size: 25 KB
Version: 1.0
Last updated: May 2026
Download the Harmonic Pattern Indicator – Free Instant Access
No payment. No catch. Enter your email below and the Harmonic Pattern Indicator file lands in your inbox within 60 seconds. Here’s everything you get:
- The non-repainting Harmonic Pattern Indicator file (.ex4) – install in 30 seconds
- Step-by-step installation guide with chart screenshots
- Best-performing settings for day trading and swing trading
- The exact D-point reversal rules I use in live trading
- Weekly trading insights from a developer with 16+ years of market experience
Download the Harmonic Pattern Indicator – Free Instant Access
No payment. No catch. Enter your email below and the Harmonic Pattern Indicator file lands in your inbox within 60 seconds. Here’s everything you get:
- The non-repainting Harmonic Pattern Indicator file (.ex4) – install in 30 seconds
- Step-by-step installation guide with chart screenshots
- Best-performing settings for scalping, day trading, and swing trading
- The exact entry and exit rules Dom uses in live trading
- Weekly trading insights from a developer with 16+ years of market experience
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Overall Rating: 4.5/5
| Category | Rating |
|---|---|
| Accuracy | 4.6/5 |
| Ease of Use | 4.4/5 |
| Features | 4.5/5 |
| Value | 4.7/5 |
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- ZigZag Indicator MT4 – Visual swing structure for spotting potential XABCD setups
- best Fibonacci indicators for MT4 – The full Fib-family ranked list
- best support and resistance indicators for MT4 – The full ranked list
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