Illegibility of text is a common problem in bad presentations. In an earlier post, I advised a minimum font size of 18 pts in a pinch, and larger in general.
However, since Calibri is now the default font for PowerPoint, it’s worth revisiting this dictum.
Because of the history of typesetting, two fonts of the same point size may not have the same visual “height.” Here’s an example:
Calibri at 18pt is visually smaller than 18pt Arial or Verdana. In fact, 20pt Calibri is about the same visual size as the other fonts at 18pts.
Historically, point size describes the height of the piece of metal upon which the typeface is embossed, not the actual height of the characters.
Here’s a picture; the dimension “c” is the point size:
There are some other fonts like this that are common to Office installations; Gil Sans and Garamond, for example.
As you might expect, the apparent line spacing is also affected for these ”smaller” fonts; in the example below, the Calibri 20pt paragraph is taller that the Arial 18pt:
To my eye, adjusting the line spacing to .9 (multiple option) makes the Calibri paragraph less “spacy:”
By the way, I do not intend to treat Arial as the gold standard here; it is, in fact, overused.
So here’s the deal: pay attention to the visual size of fonts since you can’t depend on the point size. For “small” fonts, use a minimum of 20pt and see the previous post for other considerations. Adjust the line spacing if you like the more compact appearance or have space problems.