When planning, it is often very helpful to represent scheduled tasks in a Gantt chart. Of course, dedicated project management tools, such as MS Project, provide Gantt charts out of the box. I, however, prefer in many situations OpenOffice (or Excel, I won’t repeat it any more in this post; the screenshots are taken from LibreOffice Calc, but you can do it with any spreadsheet application you like).

First you prepare the sheet: You will want to have at least a task name, a start and a due date. Then you create a time scale. In my example, I display calendar weeks, but you can of course use days or any other time unit you like.

Now the trick is to use conditional formatting to draw the Gantt bars. The formula used is:

AND($C2>D$1;$B2<=D$1+7)

• Check if the due date is after the corresponding date in the time scale.
• Check if the start date is before the corresponding date (+7 in my case, because this is a week-based scale) in the time scale.

If both conditions are true, the cell is pained blue.