Changing calendar from days to weeks?

My Gantt chart covers a large number of days and it would make the display much easier if I could change the granularity across the top to weeks. Can this be done?

I would still like to keep the task input in days, just want to compress the output by selecting weeks.

I see that visually you can use the Zoom out function. Is there any other way?

Sorry, is anything wrong with zooming out? Why looking for other ways?

That works for display, but some projects have data in weeks/months and it would be nice to input in different time units.

Day is the only time unit for task durations, sorry.