Presentation Timing Calculator

How this is calculated

A TALK'S LENGTH IS SET BY SPEAKING RATE, NOT BY SLIDE COUNT. Slides are the visible thing, so they get counted; words are what take time. TYPICAL PRESENTATION DELIVERY RUNS ROUGHLY 100 TO 150 WORDS PER MINUTE. Conversation runs faster; deliberate presentation delivery, with pauses for emphasis and time for an audience to read a slide, runs slower. The range is given rather than a single figure because it genuinely varies by speaker, by material and by how much the audience needs to absorb — technical content delivered at conversational pace is content nobody follows. ⚠️ NERVES MAKE YOU FASTER, NOT SLOWER, and this is the one people are surprised by. Under pressure most speakers accelerate, which means a talk rehearsed at a comfortable pace tends to come in SHORT on the day rather than long — while a talk that only just fits in rehearsal will usually still overrun, because the overrun comes from unplanned additions rather than from pace. Q&A IS SUBTRACTED FROM THE SLOT FIRST, deliberately. It is the first thing forgotten and it is not optional: a 20-minute slot with 5 minutes of questions is a 15-minute talk, and planning 20 minutes of content into it guarantees being cut off. THE MINUTES-PER-SLIDE OUTPUT IS A SANITY CHECK, NOT A RULE. If it comes out under about half a minute, there are too many slides for the time — not because a rule says so, but because an audience cannot absorb a slide that is on screen for twenty seconds. ⚠️ WORDS TO CUT IS THE OUTPUT THAT MATTERS when you are over. Cutting is a specific number of words, not a vague intention, and knowing it is 300 rather than 'some' is the difference between cutting a section and trimming adjectives. REHEARSE OUT LOUD AND TIMED. Reading in your head runs far faster than speaking, so a silent read-through will always tell you it fits.

Common questions

Why not just count slides?

Because slides are the visible thing and words are what take time. Two slides can hold thirty seconds and five minutes of talking respectively, so a slide count tells you almost nothing about duration. The conversion that matters is words to minutes at your speaking rate — and the slide count is only useful afterwards, as a check that no single slide is on screen for so little time that nobody can absorb it.

What speaking rate should I use?

Presentation delivery typically runs about 100 to 150 words per minute, and the range is deliberate rather than evasive: it varies by speaker, by material and by how much the audience has to take in. Conversation is faster than presentation, and technical content delivered at conversational pace is content nobody follows. The right answer is to time yourself reading your own script out loud and use that figure — it is a five-minute job and it beats any general number.

Do nerves make me slower?

Faster, almost always, and this is the thing people get backwards. Under pressure most speakers accelerate, so a talk rehearsed at a comfortable pace tends to come in short on the day rather than long. That does not mean a tight talk is safe — talks still overrun, but the overrun comes from unplanned additions, a question mid-way, or a technical problem, rather than from pace. Build the margin for those, not for slowing down.

Why subtract Q&A first?

Because it is the first thing forgotten and it is not optional. A 20-minute slot with 5 minutes of questions is a 15-minute talk, and planning 20 minutes of content into it guarantees being cut off mid-conclusion — which is the worst possible place, since the conclusion is the part people remember. Subtracting it up front means every other figure the tool gives you is about time you actually have.

How do I know if I have too many slides?

Check the minutes-per-slide figure. Under about half a minute means there are too many for the time — not because a rule says so, but because a slide on screen for twenty seconds cannot be read and listened to at once, so it is doing no work. That said, it is a sanity check rather than a target: a single slide held for eight minutes is usually fine if it is the thing being discussed, and a rapid sequence of images can be deliberate. Use it to catch the accidental case.

Take it further with AI

Copy this into ChatGPT or Claude with your own numbers filled in. It hands over the figures this calculator worked out, so the answer is built on real arithmetic instead of a guess.

I used the Presentation Timing Calculator at https://www.bfcbrilliance.com/tools/presentation-timing-calculator.

What I entered:
- Your slot (min): ___
- Q&A within the slot (min): ___
- Words in your script (words): ___
- Your speaking rate (wpm): ___
- Slides (slides): ___

What it calculated:
- Your talk runs (minutes): ___
- Speaking time available: ___
- Over or under by: ___
- Words to cut: ___
- Words the slot allows: ___

Use those figures as given — they are already worked out, so please don't recalculate or estimate your own. Help me turn them into a plan: what to buy or do, in what order, roughly what it should cost, and the mistakes people most often make with this job.

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