From the developer: "The Fibonacci Calculator calculates Retracement and Expansion Levels presenting result not only in numeric form but in graphical one as well. You don't need an additional charting software to determine input data for Fibonacci Numbers calculation. The Calculator downloads historical data for a security of your choice and draws the security's chart. You do not need to subscribe to historical data provider, it's free! You can build historical chart of three types: Line, Bar and Candlestick. Historical data available is up to: 24 months for daily charts; 4 years for weekly charts; 10 years for monthly charts. And again: you don't need to pay for that data feed! Once the historical chart built you can simply drag-and-drop data from the chart into input fields for further calculation. Depending on the trend (up or down) the Calculator grabs High or Low of the specific date and uses that data for further calculation. That insures the most precise result and prevents user error. When the Fibonacci Numbers calculated Retracement and Expansion Levels will be drawn over the chart providing you with the most convenient output. You can draw a specific Level or all the Levels. You can download fully functional trial version of the Fibonacci Calculator. You will be able to run the application 10 times. If you decide to keep using it, you will need to purchase the license."