Contraction Expansion Trend Indicator for MT4 and MT5

Written by Dominic Walsh · Published 6 Aug 2026 · Last updated 21 Sep 2026

Two envelopes, measured two ways, say something neither one manages alone. The contraction expansion trend indicator sets a spread-based envelope against a range-based one. When the first sits inside the second the market is coiling. It boxes that stretch and marks the bar the coil breaks.

This build ships as a compiled .ex4 for MT4 and .ex5 for MT5; the screenshots below come from EURUSD H1.

Platforms	MT4 (.ex4) + MT5 (.ex5)
Chart window	Main price chart
Plots	6: Coil upper, Coil lower, Expansion upper, Expansion lower, Coil resolves up, Coil resolves down
Alerts	popup, push notification, email, sound
Inputs	45

What appears on the chart

Four envelope lines and two marks.

`Coil upper` and `Coil lower` trace medium purple.

`Expansion upper` and `Expansion lower` trace gold.

`Coil resolves up` prints chartreuse using arrow 233.

`Coil resolves down` prints orange red using arrow 234.

`InpShowBoxes` draws a rectangle over each coil.

• Coil upper: line, medium purple, width 1
• Coil lower: line, medium purple, width 1
• Expansion upper: line, gold, width 2
• Expansion lower: line, gold, width 2
• Coil resolves up: arrow, chartreuse, width 2, arrow code 233
• Coil resolves down: arrow, orange red, width 2, arrow code 234

Inside the calculation

Two half-widths

`InpRegimePeriod` `20` feeds both. `InpBbMult` `2.0` scales a spread figure. `InpKcMult` `1.5` scales a range figure. Two half-widths, one window.

One against the other

The ratio between those halves is the first test. `InpContractCR` `1.00` or under calls a coil. `InpExpandCR` `1.05` or over calls a break out of one.

The second test

Range against its own baseline. `InpAtrAvgPeriod` `50` sets that baseline, and either `InpContractRER` `0.90` or `InpExpandRER` `1.00` has to agree with the first test.

Using it on a chart

Purple inside gold means the market is coiling.

Purple outside gold means it has broken out.

A box marks a coil that has finished.

Marks land on the bar a coil broke.

`InpMinCoilBars` `5` is the shortest run boxed.

`InpMinBarsApart` `6` holds same-side marks apart.

Alert channels in this build: popup, push notification, email and sound, one message per closed bar.

A coil breaking either way is what speaks. `EnableAlerts` is the master switch with `EnablePopup` on already. The push notification, the email route and the file named by `SoundFile` each begin switched off.

Every Contraction Expansion Trend Indicator input

Core settings: Regime engine

Setting	What it does	Default
InpRegimePeriod	Regime period (basis SMA, std dev and ATR). Bars behind both envelopes, `20`.	20
InpBbMult	Bollinger multiplier (statistical half width). Multiplier on the deviation half-width, `2.0`.	2.0
InpKcMult	Keltner multiplier (drawn envelope half width). Multiplier on the range half-width, `1.5`.	1.5
InpAtrAvgPeriod	ATR baseline period (longer volatility average). Window behind the range baseline, `50`.	50
InpMaxHalfAtr	Hard cap on the envelope half width (x ATR). Hard cap on the drawn half-width, `4.0`.	4.0
InpExpandCR	Expansion entry: BB/KC ratio at or above. Ratio at or over which it calls a break, `1.05`.	1.05
InpExpandRER	Expansion entry: ATR / baseline at or above.	1.00
InpContractCR	Contraction entry: BB/KC ratio at or below. Ratio at or under which it calls a coil, `1.00`.	1.00
InpContractRER	Contraction entry: ATR / baseline at or below.	0.90

Core settings: Input NAME changed, so the default signal set is byte-identi

Setting	What it does	Default
InpRequireExtremeClose	Require an extreme close outside the envelope.	off
InpMinBarsApart	Minimum bars between signals on the same side. Bars held between same-side marks, `6`.	6
InpTagGapPx	Tag gap from the arrow (pixels).	38
InpTagBars	Draw text tags over the last N bars.	300
InpMaxTags	Hard cap on BUY / SELL captions drawn at once.	30

Core settings: Text fencing

Setting	What it does	Default
InpPriceScalePx	Right margin owned by the price scale, in pixels.	62
InpOneClickWpx	Width of the one-click trade panel zone, top-left.	260
InpOneClickHpx	Height of the one-click trade panel zone, top-left.	100

Core settings: Coil boxes

Setting	What it does	Default
InpFillBoxes	Fill the boxes (outline only when off).	off
InpMinCoilBars	Minimum bars for a run to be boxed. Shortest run that earns a box, `5`.	5
InpBoxLookback	Box the last N bars only.	600

Core settings: Readout panel

Setting	What it does	Default
InpX	Panel X offset (px).	14
InpY	Panel Y offset (px) – clears one-click panel.	120

Display settings

Setting	What it does	Default
InpShowArrows	Show contraction-resolves arrows.	on
InpArrowPad	Arrow distance from the bar (points). Points between a mark and its bar, `34`.	34
InpShowTags	Show BUY / SELL text next to the arrows.	on
InpCapFontSize	BUY / SELL caption font size.	8
InpBuyColor	BUY tag colour.	chartreuse
InpSellColor	SELL tag colour.	orange red
InpAvoidPanel	Keep arrows and captions clear of the info panel.	on
InpLabelEdgePadPx	Padding kept clear at the chart edges, in pixels.	10
InpShowBoxes	Box each completed contraction run.	on
InpBoxColor	Coil box colour.	medium purple
InpShowPanel	Show the regime panel.	on
InpCorner	Panel corner (0=UL 1=UR 2=LL 3=LR).	0
InpFontSize	Panel font size.	9
InpFont	Panel font.	Consolas
InpPanelBg	Panel background.	RGB 22,14,30
InpBorderColor	Panel border.	medium purple
InpTextColor	Panel text.	gainsboro

Alert settings

Setting	What it does	Default
EnableAlerts	Master alert switch.	on
EnablePopup	Popup alert.	on
EnablePushNotify	Push notification to the mobile terminal.	off
EnableEmail	Email alert.	off
EnableSound	Play a sound file.	off
SoundFile	Sound file name.	alert.wav

Markets and timeframes

Coils need a chart where quiet stretches actually last. EURUSD H1 is the reference chart, where a boxed coil typically covers half a session. On M5 the regime flips constantly. On H4 a coil can run for most of a week.

The trade-offs

A coil breaking says nothing about how far price runs.

Both lines move only after the market does.

Boxes and captions add up to many chart objects.

Two tests agreeing is still two late measurements.

Copy the compiled Contraction Expansion Trend Indicator file into your MQL4/Indicators folder, and the MT5 build into MQL5/Indicators, then restart the terminal and drag it onto a chart. The step-by-step guide with screenshots is at how to install MT4 and MT5 indicators.

Background reading on the method behind the Contraction Expansion Trend Indicator: Bollinger BandWidth at StockCharts ChartSchool, Squeeze at Investopedia.

Download the Contraction Expansion Trend Indicator for MT4 and MT5

The zip holds the compiled Contraction Expansion Trend Indicator build for MT4 and MT5, plus a short README. Compiled files only, no source. Enter your email below and the download link arrives in your inbox.

FAQ

What does the ratio between InpBbMult and InpKcMult measure?

How the deviation of closes compares against the size of recent bars. When the statistical half-width slips inside the range half-width, closes have bunched relative to how far bars are travelling, which is the coil condition.

Why does InpContractRER 0.90 add a second test?

Because the ratio alone can drop for the wrong reason. Requiring range to sit under ninety percent of its fifty-bar baseline confirms that the market really is quiet rather than merely producing tightly grouped closes.

What does InpMaxHalfAtr 4.0 prevent?

The drawn envelope from exploding after a shock. It caps the half-width at four ranges, so one enormous bar cannot stretch the lines so far that the chart becomes unreadable for the next fifty bars.

When does a Coil resolves up arrow print?

On the bar a boxed coil stretch ends upward. The rectangle marks where the market was quiet; the arrow marks where it stopped being quiet, which are two different pieces of information.

Are results guaranteed?

No. Trading involves risk. Results are not guaranteed; past performance is not indicative of future results. Use the Contraction Expansion Trend Indicator as one input. Always backtest before trading live.