The internet is filled with gantt chart samples, here is one form my side.
So whats new in it, well all the excel based gantt charts I came across used two different rows to show the budget and actual progress,
whereas here with the use of conditional formatting budget/actual progress are shown in same row. Here are the steps to build it
1. write budget and actual start and end dates activity wise
2. on left side calculate duration of each activity
3. further left calculate delay or early on start and end of each activity, conditional format it to highlight any delay
4. write dates in top row beside End of Actual and format them to vertical alignment, further format cells for lower column width
5. Conditional format (using format only the cell that contain option) the top row of chart area with pattern for budget activity and color for actual activity, as shown in figure below
6. copy the format to rest of chart area
7. Do cosmetics as you like.
link to file