User preferences for reading text on the web
Hot on the heels of type face in terms of the impact on readability is font size. A 'readable' font can quickly be rendered illegible at too small or large a size.
The following preferences are of course only relevant to those respondents who chose the particular font in the first place. Someone who found Arial to be most readable doesn't express an opinion about the preferred size for Helvetica, for example.
Arial was most popular around the 14pt to 15pt mark, split fairly evenly between about 44% of respondents, although 14pt shades it slightly. The next largest group couldn't quite decide between 12pt and 13pt, which made up just under 20% of the votes between them. 16pt and 18pt got around 7% between them, with the rest being made up of a smattering of larger sizes, with the enormous 22pt getting a couple of percent of the votes.
Helvetica showed similar results, but with a bias towards sightly smaller sizes. For this font, 14pt was less popular than 12pt and 13pt, which both gained ground to around 15% at the former's expense, which came in nearer 13%. 15pt was therefore a clearer favourite in Helvetica, although with a little over 20% it was almost identical to the result for Arial. There was not much argument to be had for one size over another anywhere from 12pt to 14pt, and there was a similar long tail to Arial's up to 22pt, with a slight peak at 18pt.
Lucida had a much more predictable 'curve' to the preferences, with a peak around 13pt (with over 20% of the votes) which tailed off either side. 11pt was about as small as people wanted to go with this type face, and the tail to larger sizes petered out at around 18pt (although a few people did like it larger) with a slight peak at 17pt. 13pt was therefore the 'winner' but if you used 12pt or 14pt you wouldn't face too much argument.
Trebuchet on the other hand is a very mixed bag, although it does have one of the clearest size preferences of all the type faces surveyed - 13pt, which garners over 30% of the votes! Either side of that size, 12pt and 14pt get around half the number of votes each, with 14pt the more popular. Then there's a 'hole' around 16pt, whereas larger sizes from 18pt to 20pt get a much stronger showing than the other fonts so far.
Verdana shows an almost bizarrely flat response all the way from 10pt (about 5%) to 18pt (just under 10%), with a couple of dips at 15pt and 17pt (to below 5%). If you're looking for a clear favourite I'm afraid our respondents are split evenly between 12pt, 13pt and 16pt, all of which are about the 12% mark.
Times has a similar response curve to Verdana -?flat and wide across the font sizes from 12pt to 20pt. It shows a clearer winner however, with 15pt standing out as the only one breaking the 10% mark with about 14% of the votes.
Georgia demonstrates much clearer trends, thankfully! A prominent peak of preferences for 14pt (just shy of 30%) starts building at 12pt (with about 12%) and trails away sharply after 15pt, which has just under 20% of the votes. A very low peak emerges around the 20pt mark, but this only accounts for a few percentage points.
Courier, the ugly-but-useful duckling, shows 12pt as the massive winner with almost 50% of the voters deeming it most readable. The type face doesn't show as much liking for larger font sizes, with no real trace of preference for sizes above 18pt, in contrast to some of the other type faces.
In summary, I think it's fair to say that your fonts are in the 'readable zone' if they're around 12pt to 15pt.
Tomorrow things get really interesting when we introduce column widths into the mix!