Study & writing
Presentation slides calculator
Enter the length of your talk, the time kept for questions and your slide style to get a sensible number of slides.
The range is the target ±20%: fewer slides for a story-driven talk, more for quick visual ones.
How the slide count is estimated
First the question time is taken off the talk, because nobody presents new slides during Q&A. The speaking minutes are then divided by the time you spend on each slide: about 2 minutes for a detailed slide with a chart or a process to explain, 1 minute for a standard slide with a heading and a few points, and 30 seconds for a fast, mostly visual slide. The range shown is that target ±20%, since real decks mix slide types.
Example: a 20-minute slot with 5 minutes for questions leaves 15 minutes of speaking. In the standard style that is 15 ÷ 1 = 15 slides, with a sensible range of 12–18. At a comfortable 140 words per minute you will say about 2,100 words, or roughly 140 per slide.
| Speaking time | Detailed (2 min) | Standard (1 min) | Fast (30 s) |
|---|---|---|---|
| 5 min | 3 | 5 | 10 |
| 10 min | 5 | 10 | 20 |
| 15 min | 8 | 15 | 30 |
| 20 min | 10 | 20 | 40 |
| 30 min | 15 | 30 | 60 |
| 45 min | 23 | 45 | 90 |
| 60 min | 30 | 60 | 120 |
Fitting the deck to the audience
The number of slides matters less than the time each one stays on screen. A board meeting or a technical review tends to need detailed slides that stay up while people read and ask questions; a conference talk or a lightning talk works better with many quick visuals and very little text. Guy Kawasaki's well-known 10/20/30 rule for pitches (10 slides, 20 minutes, no font smaller than 30 points) is the detailed style in practice: two minutes per slide.
Title, agenda and closing slides usually pass in a few seconds, so you do not have to count them against the total. Backup slides for likely questions can go after the closing slide, where they do not eat into the speaking time.
Rehearse once with a timer. If you run long, cut whole slides rather than talking faster, because speeding up makes every remaining slide harder to follow. A good check is the word count per slide: if your notes for one slide run past about 280 words, that slide holds more than two minutes of talking and is probably two slides.
Frequently asked questions
How many slides for a 10-minute presentation?
About 10 slides at one minute per slide. A detailed, data-heavy talk works with around 5, and a fast, image-led talk can use up to 20.
How many slides for a 20-minute presentation?
Around 15 to 20. Without questions, 20 standard slides fit; if you keep 5 minutes for Q&A, plan about 15 slides for the 15 minutes of speaking.
How long should I spend on each slide?
One to two minutes is typical for slides with text or a chart. Purely visual slides can move every 20 to 30 seconds, while a complex diagram may need three minutes or more.