How to boldface ALL of a book so it’s simpler to read on your E Ink gizmo: Easy Calibre tweak

image E Ink’s low contrast---between the text and  background on the screen---annoys many an e-book-lover. I’m one of them. My wife has an even worse problem with the low contrast and refuses to mess with E Ink gizmos. And here E Ink is supposed to be nicer for human eyes than LCDs are.

But what if you could use boldface to thicken the characters and increase the perceived contrast? A quick, easy tweak in the just-updated Calibre e-book management program will work with many e-book files---not all, alas. What’s more, I’m not sure about this for the Kindle even if the tip is still worth trying on it. Also, you can’t use the bolding trick with DRMed e-books. But considering the number of public domain classics and other nonDRMed books online, give it a shot---your success rate may actually be high. The tweak takes just two minutes if Calibre is on your desktop machine. Here’s what you do:

1. Install the free Calibre software (Web site here, download links here) if your aren’t using it already. This week we pointed to a Calibre guide written with Kindle novices in mind. Many of the concepts there would apply to other devices like the Sony Reader. Calibre isn’t as easy to use as a conversion service like Amazon’s own, or the new third-party one called RetroRead, about which I’ll write further today or next week (sorry for the delay). But then conversion services won’t let you do the bolding trick.

2. Click on the Preferences at the top of your screen toward the right. That’s the hammer icon.

3. Choose Conversion, the third icon down.

4. Then within the box labeled Extra CSS, insert the following code: body { font-weight: bold }

5. Click OK.

With many e-book files and maybe even most, your books will be all-bolded when you convert. You can even “convert” within the same format—ePub to ePub. Mercy toward your eyes! Worked fine with my Sony Reader on test Google Books files. files were less consistent. Feedbooks also presented a problem. I don’t know who’s in the right or wrong technically. I’m just telling you what happened. As for the Kindle, the trick may have worked on certain files. But the bold and nonbold styles on the Kindle aren’t easy for me to tell apart at times if I don’t have side-by-side comparisons. So that’s why I said earlier, “Not sure.”

Of course, if your e-reader can deal with PDF, you could also create book files with everything bolded. OpenOffice is one way turn RTF-format files—offered by and some other public domain collections—into PDF. You could bold the fonts within OO before the conversion. But ePub generally works better on small screens than PDF does, so that’s why it’s hand to know the just-described bolding trick within Calibre.

Mind you, the real solution to the contrast problem would be for device-makers to use the Embolden command—turn everything into boldface—that the Cybook Gen3 uses. Improved E Ink tech should also help. The contrast of the newer displays is better than it used to be. It just isn’t good enough yet for Carly and me.

Thanks: To Kovid Goyal, Calibre’s brilliant and ever-diligent developer. I tried the bold command but didn’t see results, until I went on to other files after he said that bolding wouldn’t work with all. Now how about some feedback? How does the trick work for you?

Image credit: CC-licensed eye image from Orangeacid.

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About David Rothman (6820 Articles)
David Rothman is the founder and publisher of the TeleRead e-book site and cofounder of He is also author of The Solomon Scandals novel and six tech-related books on topics ranging from the Internet to laptops. Passionate on digital divide issues, he is now pushing for the creation of a national digital library endowment.

8 Comments on How to boldface ALL of a book so it’s simpler to read on your E Ink gizmo: Easy Calibre tweak

  1. hi,
    This worked on a PDF ebook(lucifer’s lodge by william.h.kennedy)i bought from the lulu e-store.

    I used the calibre tool/hack to convert from PDF to E-PUB.

    The font em-boldening does work but the font size wasn’t the was larger than normal and the formatting was different.

  2. …forgot to add i’m using the sony e-book reader prs 505…and calibre 6.3?(the latest update as of 26/12/2009),on leopard.

    Thanks for your blog David…v.helpful and informative.

  3. This way works OK, but misses all the emphatic bolded text of the original texts. A much more elegant and almost of equal ease of implementing is the use of custom fonts. For example in the Sony series, all you need to do is drop some fonts in the data folder of your reader and then use the font-face html in the css area of Calibre. To get very easy step by step instructions, just see here.

  4. Mark: Thanks for the valuable link, but keep in mind that my goal was a quick, easy solution for a variety of devices. People would have to extrapolate and experiment to apply the Sony-related instructions to other machines. Glad to have the link, though! David

  5. UK Marty: Useful info, and I hope others will share their own experiences! David

  6. All this is a hack to overcome shitty screenfonts with single-pixel stems. Your solution isn’t bold, it’s (a) a different typeface or (b) a better rendering engine.

  7. Thanks, Joe, but we’re talking about who’ve already invested in Sony Readers, etc., and want a quick solution. Bolding won’t always work. But it’s better than nothing.


  8. So this explains the scourge of bolded text I’ve had to put up when downloading ebooks. My Kindle3’s contrast ratio is pretty high and doesn’t need this “hack”. I also can’t stand to read bold body text – it’s like someone’s shouting at me nonstop.

    At least I now know how to use Extra CSS to remove the bolded text in Calibre without having to keep searching for a copy with normal text.

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