All fonts are created equal. But some are more equal than others.
The terms ‘proportional’ and ‘non-proportional’ are quite misleading. Contrary to what their names suggest, a proportional font is one where different shaped letters can take up different amounts of space (eg: Times New Roman).
For the purposes of a manuscript (and particularly wordcount or booklength in publishing) it is important that you use a non-proportional font (or monospaced or fixed-width font). That is, a font where every character takes up the same amount of space regardless of whether it’s our skinny friends ‘i’, ‘l’ or ‘t’; or our fat little friends ‘w’ and ‘m’.
This is so that you can reliably know that each 60-space line will have 60 characters in it for the purposes of accurate word-counting. (Try it; Courier = 60 ‘i’s to a line whereas Times Roman = 120 ‘i’s to a line).
NOTES ABOUT FONT SELECTION
- Don’t buck the system when it comes to fonts. You might think that providing your manuscript in Goudy Oldstyle instead of Courier will be delightfully refreshing or a point of difference; it won’t, it might just annoy an editor or editorial assistant enough that they won’t put your book through to the next pass.
- ‘Serif’ (with little dressy bits on letters) or ‘sans serif’ (without little dressy bits) is not the same as proportional and non-proportional.

So Courier and Times New Roman are different (non-proportional vs proportional). That makes sense. However, why are more and more writing guidelines giving the green light on either one of them. Is it a location thing? Courier in down under and TNR in the USA?
Hi Nancy!
I don’t think it’s region specific but I think that the old-school way of calculating word-count/page numbers has just been bested by modern computer wordcounts. They are distinctly different in outcome (eg: 75,000 courier words versus 75,000 TNR words) so I can only assume that the pubs have their own ways of turning computer wordcount into approximate page count (probably by applying an old school template to a new school manuscript). So they’re basically saying they have ways of calculating the total page-count/word-count either way.
xx