Trends/Fibonacci and harmonic patterns

Fibonacci extension

Levels drawn above a swing high (or below a swing low) at multiples of the first move, to see how far price has gone past it.

Fibonacci and harmonic patternsBest on 6M, 1Y, 3YAlso called Fib extension

Illustration of the Fibonacci extension shape. It is a sketch, not real price data.

What it shows

An extension measures how far price has travelled beyond a previous swing. It draws lines at 127.2%, 161.8% and 261.8% of the first swing's height, measured from the swing's starting point.

Many traders use them as reference points when price is moving into new territory with no older levels nearby.

How we find it

The same code that draws it on your chart follows these steps, with the same result every time.

Find a major swing from a low to a high.
Measure its height.
Draw lines at 100%, 127.2%, 161.8% and 261.8% of that height, measured up from the swing low.
Show only levels within the visible price range.

Starting values: Levels 100, 127.2, 161.8, 261.8%; Minimum swing 10% of price. These are proposed and will be tuned on real price data before launch.

How to read it

The gold line is 100%: the previous swing high.
Cyan lines above it are extensions.
Price crossing a line shows how many multiples of the first swing it has covered.

Status labels you may see

Label	What it means
Below the swing high	Price is under 100%.
Between 100% and 127.2%	Slightly past the old high.
Beyond 161.8%	More than 1.6 times the first swing.

What cancels it

A close below the start of the swing.

What traders check next

Whether other levels fall near the same price.
Whether price paused at an extension.
Whether the first swing is the best reference.

Limits

Choosing the swing changes all levels.
The ratios are conventions.
Extensions are not found in the data, they are drawn from it.

Try it in forecastviz

Open any ticker and choose Fibonacci and harmonic patterns → Fibonacci extension in the left menu.
Switch between 6M, 1Y, 3Y to see how the picture changes.
Compare with Fibonacci retracement and Fibonacci projection on the same chart.

Open on a ticker

Questions

What is the difference from retracement?

Retracement divides a swing backward. Extension projects its size forward.

Which ratios are used?

127.2% and 161.8% are the most common.