Presentation time calculator
Slides times words per slide, divided by your speaking rate, plus question time. The rough guide of one to two minutes a slide falls out of it, but the words are what actually determine the length.
How to time a presentation
Almost everyone plans too many slides, and the reason is that a slide takes far longer to talk through than it takes to make. Counting the words you will actually say is a much better predictor than counting slides, because a title slide and a dense diagram are both "one slide" and are not remotely the same duration. Two practical rules: rehearse to about ninety percent of your slot, because you will run over on the day, and if you have twenty minutes, plan for fifteen of content — the questions and the walking to the lectern are real minutes.
Questions
Fifteen to twenty if they are light, ten if they are dense. Count the words you will say rather than the slides.