How to calculate slide duration? | Powerpoint 2007

Go under Slide Show tab and to Set Up section. Choose the box “Use Rehearsed Timings” and click on “Rehearse Timings”. Now you can tailor your presentation timings to your needs. You can see the seconds pass and after the determined time you need has elapsed, press on either “Next”, which is the first button in the menu and takes you to next slide or “Pause” if you want to pause the timing rehearsal or “Repeat”, which would restart the rehearsal.