When I first started writing speeches, I struggled to know how many words to write for a speech of a given length.  The only way I would know was to rehearse the speech and time how long it lasted.

Now I have learned that I typically speak at an average of  80-100 words per minute when presenting in public and so I can quickly calculate how many words I need to write  i.e. 400-500 words for a five minute speech and so on.

Now not everybody speaks at the same pace.   Some books quote the normal speaking rate as around 125 words per minute but remember that there is a big difference between normal conversation and public speaking.   The best public speakers tend, on average to speak a bit slower so i would recommend that you start of with around 100 wpm and see how you get on.

Most word processors have a word count function built into them so it’s easy to check how much you have written.

Of course it goes without saying that when writing a speech of any length don’t  forget the basics.  You need an interesting opening, a powerful conclusion and relevant body content. and remember to rehearse it out loud.  Give as much time to planning the delivery as you do the planning the content.

Good luck

Gavin