In your Bookeo Appointments account, you can set the "granularity" of the calendar. This determines how many cells per hour are displayed in the manager calendar, and what times customers can make a booking for.
1. Go to Settings>Booking Preferences
2. Go to the Time resolution section
3. From the scroll down menu, select the:
- Time resolution for you  (from 5 min to 1hr)
- Time resolution for customer  (from 5 min to 1hr)
In this settings example, your Bookeo calendar will have a 15 min grid
and your customers will only be able to book at 30 min intervals