This indicator/tool (Auto Fibo) draws Fibonacci Retracement Levels automatically on chart. The algorithm of the Indicator Plots the extreme points and puts the retracement levels in order by itself with 100% sensitivity. The key point is that to arrange the length of the "Days Back" to arrange the correct extreme points. Like the other auto plotting tools, the levels can change when the time frame of the chart changes, in contrast with manually drawn Fibo levels.
In technical analysis , a Fibonacci retracement is created by taking two extreme points (usually a major peak and trough) on a stock chart and dividing the vertical distance by the key Fibonacci ratios of 23.6%, 38.2%, 50%, 61.8% and 100%.