I am researching very nice (very readable and enjoyable) screen fonts for reading ebooks, either in HTML or EPUB format. I want this both as an avid reader and as an ebook formatter. I think the key fonts to choose are those for body text, since that is what one spends almost all one's time looking at. The following is a (long) summary of my search so far.
Criteria for all fonts: Fonts must be free (no charge), and must have a license that allows use, distribution and modification. I'd like to be able to share the books I format with anyone.
Criteria for sans serif text fonts: Fonts should display decently at 6-8 pts, have R/I/B/BI (regular, italics, bold, bold italics), small caps, lining and text figures, and basic Latin ligatures. I say 6-8 pts not because I intend to read long passages at such small sizes, but because I think legibility at small sizes is a very good, and easy to evaluate, indicator of quality at larger text sizes (9-14 pts). A font that struggles at 8 pt doesn't magically turn great at 10 pt.
Judged suitable as a screen body text font: Dejavu Sans, Liberation Sans, PT Sans, and Dejavu Sans Condensed. (I used Microsoft Verdana, Segoe UI, Arial, Corbel, and Calibri for comparison. No wonder people think Verdana is highly readable – the lower case and numerals are huge in comparison to all the others!)
I judged not as suitable as those above: Aller, Aurulent Sans, Candela, CartoGothic, FreeSans, Iwona, Kurier, Linux Biolinum, TexGyreAdventor, TexGyreHeros. All these do have bold/italic variants.
Fairly suitable, but judged superfluous in the end: Arimo, Lato, and Nobile. Lato is worth revisiting later in 2011 if/when the character set is expanded. Droid Sans would be listed here too, but it has no italic.
All fonts of the best choices:
Dejavu Sans
Dejavu Sans oblique
Dejavu Sans bold
Dejavu Sans bold oblique
DejaVu Sans extralight
Dejavu Sans condensed
Dejavu Sans condensed oblique
Dejavu Sans condensed bold
Dejavu Sans condensed bold oblique
Liberation Sans
Liberation Sans italic
Liberation Sans bold
Liberation Sans bold italic
Liberation Sans narrow (not as legible in small sizes as Dejavu Sans condensed)
Liberation Sans narrow italic
Liberation Sans narrow bold
Liberation Sans narrow bold italic
PT Sans
PT Sans italic
PT Sans bold
PT Sans bold italic
PT Sans caption (very legible at small sizes, but there is no italic)
PT Sans caption bold
PT Sans narrow (not as legible in small sizes as Dejavu Sans condensed)
PT Sans narrow bold
Serif text fonts: Fonts must display decently at 6-8 pts, have R/I/B/BI, small caps, lining and text figures, and basic Latin ligatures.
Judged suitable as a screen font: Dejavu Serif, Dejavu Serif Condensed, PT Serif, Liberation Serif. (Microsoft Constantia, Cambria, and Times New Roman were used for comparison.)
Judged not as suitable as those above: Bergamo, Crimson Text, FreeSerif, I.M. Fell fonts, Linux Libertine, Old Standard, TexGyreBonum, TGPagella, TexGyreSchola, TexGyreHermes.
Fairly suitable, but judged superfluous in the end: Droid Serif, Gentium Basic, Gentium Book Basic, Tinos.
All fonts of the best choices:
Dejavu Serif
Dejavu Serif italic
Dejavu Serif bold
Dejavu Serif bold italic
Dejavu Serif condensed
Dejavu Serif condensed italic
Dejavu Serif condensed bold
Dejavu Serif condensed bold italic
Liberation Serif
Liberation Serif italic
Liberation Serif bold
Liberation Serif bold italic
PT Serif
PT Serif italic
PT Serif bold
PT Serif bold italic
PT Serif caption (very legible at small sizes, but there is no bold)
PT Serif caption italic
Mono text font tests: Fonts must display decently at 6-8 pts, have R/I/B/BI and, preferably, small caps. Specific needs: typewriter font.
Judged suitable as a screen font: Dejavu Sans Mono and Liberation Mono (there is no PT Mono).
Judged not as suitable as those above: FreeMono.
All fonts of the best choices:
Dejavu Sans Mono
Dejavu Sans Mono oblique
Dejavu Sans Mono bold
Dejavu Sans Mono bold oblique
Liberation Mono italic
Liberation Mono italic
Liberation Mono bold
Liberation Mono bold italic
I have yet to find a suitable typewriter font. "Courier New" and “Courier” covers Windows and Mac for now, but not Linux and e-book readers.
Other fonts (e.g. men's and women's handwriting for letters, notes, decorative, etc.): These vary in style greatly, and many are available at free font sites (e.g. FontSquirrel, Google Fonts). Select as each particular book, passage or character suggests. No general need for font variants or features.
At this point, the Dejavu fonts were my favorite.
Having found three serif, three sans serif, and two monospaced fonts that met the first requirement, I compared the color and spacing of each on a sample screen page consisting of two identical paragraphs of “lorem ipsum” text (courtesy of
www.lipsum.com), each marked up in one font. Using text you don't understand lets you concentrate on the appearance rather than the meaning. Here is the sample paragraph, in case someone wants to try this themselves:
“Lorem ipsum dolor sit amet, consectetur adipiscing elit. Donec consectetur vehicula augue, vitae ornare urna condimentum id. Morbi ac tellus quis est imperdiet congue. Pellentesque nunc orci, vestibulum vitae fringilla hendrerit, auctor quis lacus. Integer non metus mauris, id ultricies magna. Vestibulum ante ipsum primis in faucibus orci luctus et ultrices posuere cubilia Curae; Duis et convallis eros. Maecenas porta, lectus eget adipiscing dapibus, eros nunc varius urna, non malesuada ipsum justo eget est. Vestibulum ante ipsum primis in faucibus orci luctus et ultrices posuere cubilia Curae; Nullam at nunc purus. Nulla pharetra auctor suscipit. Suspendisse tincidunt purus quis risus rutrum id rhoncus nisl auctor. Nulla ultrices nunc nec velit ultricies ullamcorper. Fusce quis sem sed nisi convallis cursus. Etiam lectus felis, convallis eu aliquet sit amet, ullamcorper ac nunc. Fusce quis dui lorem. Maecenas ac nisl metus, ac tristique mauris. Phasellus consequat velit in justo tincidunt pharetra et et arcu. Cras non libero vel purus consectetur scelerisque. Aenean a dolor felis. Donec auctor neque et turpis interdum a dapibus augue gravida. Praesent sagittis porttitor mattis. Proin iaculis scelerisque imperdiet. Morbi adipiscing, augue in malesuada imperdiet, lorem mi tincidunt dolor, porttitor aliquet tortor dolor sed sapien. Quisque suscipit venenatis libero, a scelerisque purus volutpat ac. Mauris faucibus, diam at viverra congue, velit turpis varius odio, sit amet aliquam lorem ante pretium nulla. Etiam sit amet tortor elit.”
I compared the relative appearance of the text in each font, highlighting any character spacing or other appearance or readability issues as I went so I could review and count them. I ran the test at two point sizes for each comparison to make sure the results were valid.
During the exercise, it became obvious that the Dejavu fonts are not as well spaced as the other two. Counting the highlights, I averaged between 30-40 marks per the above paragraph in point sizes 10-12 for both the serif and sans regular Dejavu fonts. I averaged less than 10 marks for each of the other two – Liberation and PT (Paratype). This overrode any other differences. To my eye, the Dejavu font spacing issues (on my system, who knows what they look like on another) are quite an unpleasant distraction from reading. Spacing is not a barrier to reading pleasure with either of the other two font families.
Comparing Liberation v PT fonts required consideration of other things besides spacing, and being more specific. In the regular sans, the two fonts are approximately the same size. Liberation Sans would benefit from the greater line spacing of PT Sans. The PT Sans “M” is a bit dark in color on the screen, and catches the eye a bit (this seems to be a common problem). Also, strangely, I noticed the PT Sans space character is too narrow for my comfort. I have never noticed this in a font before. Either of these two fonts could be very acceptable for long sessions of reading.
On the serif side, PT Serif is noticeably larger than Liberation Serif. PT @ 10pt is about the same visual size as Liberation at 11.5pt. Unlike the sans fonts, the interline spacing is similar. There are no problems with the PT “M” or space character. PT may have slightly better spacing than Liberation in general - it just looks smoother.
The big difference between these two serif fonts is the glyph shapes. PT Serif has rounder glyphs; Liberation Serif is squarer, and adds an overall impression of emphasis on vertical strokes that may not be as appealing for some. The only functional issue is with the Liberation lower case “m”. Its squareness across the top makes it too hard to distinguish from “rn”. I would enjoy long reading sessions with PT Serif, but not as much so with Liberation Serif.
That's where I am now. I think neither PT nor Liberation has text figures or small caps. I may be able to hack tolerable small caps in CSS. There's nothing to be done about the text figures, though, unless I copy them from another font.
BTW, all these fonts have extensive character sets, and the files are quite large compared to most Western font files. If you want to use them, you should either install them on your reading device, or "subset" them - remove the parts you don't need - before embedding them in an EPUB book or an HTML package or WOFFing them. Is WOFF a verb yet?
As of 8 March 2011, the current version of Dejavu font package is 2.33, the Liberation font package is 1.06, and the PT font version is 2.003 (from Sans font file).
Online sources:
Dejavu fonts:
http://dejavu-fonts.org/wiki/Main_Page
Liberation fonts:
https://fedorahosted.org/liberation-fonts/
PT fonts:
http://www.paratype.com/public/