I’m still not sure if it is what we call a PhD defense (the final step in getting a PhD at most schools) or if it is an oral exam done in order to get approval for your thesis topic.

Either way, my advice is to do the following:

If there is a guide document at your university — follow that style. In my experience, they usually provide these for the format of the dissertation — but not for presentations.

If none exists, I suggest you use a presentation tool like Powerpoint that will pick the font size for you. Use bullit points and try to keep the number of points you make limited to about five per slide (and never more than seven). If you do this, you will find that the main points are 24 point to 28 point. Subheadings should be at least 20.

Keep the detail of the slides at ‘talking points’ and only provide lots of detail if it is absolutely needed. You may want to make up a number of extra slides that you keep at the end with formulas and more detail — in case you are asked questions about them.

You may want to go to the room where you are presenting ahead of time and make sure that the slides can be read fromthe back of the room.

Good luck — and congratulations.