How many slides can you have in a PowerPoint?
You can have, essentially, an unlimited number of slides
in Powerpoint. Presentation size will be limited by how you
plan to move the file around however, for example, will it
be too large to e-mail or transfer via a USB device ("jump
drive / thumb drive").
The common rule-of-thumb is that a presenter will speak to
two slides per minute on average, therefore a fifteen minute
speech will be roughly 30 slides, and around 5mb.