A question I’m often asked is, “How do you know how long your speech will be before you deliver it?” One important way is actually to have a dress rehearsal before you give the talk. If possible, go to the room where you will speak, taking all your visuals, and deliver it exactly as you plan to in the actual speaking situation. If you are using PowerPoint or some other similar software, you want to include that part of the presentation in your timed practice session. If you don’t practice with your visuals, your presentation time may be misleading because any kind of visual will usually add to your overall length. Time it and you will be pretty confident about the length of your presentation. Have a person sit in on your presentation so that you will be able to gauge audience reaction and realistically know when to pause and change rate based on the person’s nonverbal feedback.
Another way of helping you determine the length of your presentation is to practice aloud sections of your talk and measure the minutes in each section. If you are an experienced speaker, you will soon learn to determine how much time a page of notes will take. Look over the pages or notecards; total the time it usually takes you for each section, and that will give you a good estimate of overall time of your presentation.
One factor to consider by your past experience is whether you usually run longer or shorter in the actual presentation. Thus you can adjust accordingly with each new presentation. I tend to go short in practice and longer in the specific presentation with a live audience, but for some people it’s the other way around.
If you are using a manuscript, a rule of thumb for 8 ½” x 11” sheets of paper, double-spaced with an inch margin, is that each page will take about two and a half minutes to deliver.
In my beginning speech class, I found that students often went short of the time limit at the start of the semester, but by the end of the semester, they were pretty much within 30 seconds when they finished the presentation. A main reason is they had incorporated the above ideas in their practice sessions.
Knowing that you will be unlikely to go way overtime or finish several minutes before your allotted time is up goes a long way to give you more poise and confidence in delivering your actual presentation.