back to article Wolfing down ebooks during lockdown? You might want to check out Calibre, the Swiss Army ebook tool

In this week's edition of our column on free and open-source software, El Reg takes a look at Calibre, which converts almost any file type into almost any other file type, so you can read whatever you want, wherever you want, no matter what format it's in. It's free and runs on Windows, Linux and Mac. There's more to ebooks …

  1. PhilipN Silver badge

    Upwards thumb

    Not just one of the most useful apps ever but also one of the most attractive, artistic even, interfaces.

    1. Anonymous Coward
      Anonymous Coward

      Re: Upwards thumb

      This is weird, because the interface is one of the thing I really don't like about it. I have pretty stop using it beyond the converter. I just keep it sorted so I can see what I have added recently and use Okular for a viewer. Just pretty much use it to convert books for my Kindle.

      The main interface always starts with the toolbar enabled only that includes that stupid animated begging for money icon. That gets removed first.

      Then there is the giant ass list of books. I really wish it had an option akin to what Winamp does with my music. Tags are not that great of an organizing method. Too many things end up with the same tags so the sorting really doesn't work that well. Then there is the manual process of needing to set them each and every book.

      Then there is the mess that is the viewer and its interface. First of all, it appears to be a phone app masquerading as a desktop app with it. Right click brings a hilariously bad look menu that is not in any way logically laid out and not the context menu you want. But there isn't one. What you get instead is a group of icons whenever you select text with the tool clearly designed for fingers and not mice. Why this is so touch base when everything else isn't.

      It also loses points for not allowing me to save my settings in the library location. I do not know how many times I have forgotten that it doesn't do that and I have to resettup everything.

      1. Geoffrey W

        Re: Upwards thumb

        I have a few issues with Calibre so I tried Okular. Ugh. I think I have more issues with Okular. It looks dreadful. The font used is horrible and I couldn't find any option to change it. If font can be changed I don't know where it's hidden. Installed it; uninstalled it 30 minutes later. Why is it so hard to find a good Epub reader on the PC? I think I'll stick with Calibre. Just don't go criticizing the thing to the Author - his name is Kovid, of all things - He can be a bit abrupt. :-)

        1. ThatOne Silver badge

          Re: Upwards thumb

          > Why is it so hard to find a good Epub reader on the PC?

          As a reader I use FBReader, both on my phone, tablet and (Linux) laptop. There is a Windows version IIRC, but I've never checked it. For Android you'll find it on Play Store, for Linux it's in Mint's Software manager.

          I do use Calibre too, but only to turn old .doc texts into Epub files.

          1. Geoffrey W

            Re: Upwards thumb

            Yep. FBReader on Android, but the last time I looked at the Windows version - admittedly a while ago now - it looked like it hadn't been updated since neolithic times and seemed a bit clunky, and I wasn't happy. Real reading, though, is done on a dedicated EReader. I have only bought one dead tree book in the past two years.

          2. Uncle Slacky Silver badge

            Re: Upwards thumb

            On Android (F-Droid) I use LibreraPro.

          3. CrazyOldCatMan Silver badge

            Re: Upwards thumb

            As a reader I use FBReader, both on my phone, tablet

            Likewise. And Calibre Companion on the tablet to transfer epubs from Calibre on my Mac (as a wireless device which means that the Reading List plugin activates and copies the queued books automatically).

        2. keith_w

          Re: Upwards thumb

          I use the Kobo reader, whose default format is EPub, on my Windows and Android systems.

        3. LybsterRoy Silver badge

          Re: Upwards thumb

          I use Sumatra

      2. Anonymous Coward
        Anonymous Coward

        Re: Upwards thumb

        "The main interface always starts with the toolbar enabled only that includes that stupid animated begging for money icon. That gets removed first."

        So what's your problem? The full version of Calibre is provided completely free for as long as you want, has a toolbar icon which let's you donate to contribute to development costs, but only if you want, and allows you to remove the donate button from the toolbar with a single click. Hardly begging, is it?

        The developer clearly works hard to provide very frequent updates to deal with new hardware compatibility etc and any reported bugs and has done so for many years. It's as stable as a rock on Windows and Android.Yet you complain about the mere existence of a toolbar icon allowing you to contribute?

        Too bad you don't like the interface - personally I find it fine, as are all the plugins for my particular ereader which extend Calibre's usefulness further.

        Do let us know when you find any piece of software remotely as useful offering the same set of features as Calibre, at any price. When you find it, might I suggest a relevant ebook for you to read - Christopher Caldwell's "The Age of Entitlement: America Since the Sixties".

        1. Hogbert

          Re: Upwards thumb

          Agree, I think I have donated twice, maybe 3 times.

          The tools for categorizing are quite excellent. You don't have to have everything in one huge list; if you don't want to sort and group by tags, it is actually quite easy to set up different libraries and move books into the appropriate one. If I want to look up technical books I switch to the tech library. For cooking and food books etc I switch to the home library. Scifi is by far the largest library, and for that I am more interested in grouping by author and series number.

          People should really learn to use their tools before complaining about them.

    2. Anonymous Coward
      Anonymous Coward

      Re: Upwards thumb

      If my elderly mother can use the interface it's good enough I can tell you that much. And that's been for 5-6 years now.

      1. Doctor Syntax Silver badge

        Re: Upwards thumb

        I suppose it depends on whether she has established prior expectations of how user interfaces will work.

        If you were to design a vehicle control on the basis that the vehicle will turn in the direction in which the lower part of the steering wheel turns then a new driver will learn that and find it natural. Experienced drivers would crash within minutes.

    3. doublelayer Silver badge

      Re: Upwards thumb

      I don't like the interface, but fortunately for me, it also includes a bunch of internal command line tools which can be put into any interface you want. So I am still using it even though I haven't had to get lost looking for the right control or dismissing an irrelevant function in a while.

    4. John Brown (no body) Silver badge

      Re: Upwards thumb

      "one of the most attractive, artistic even, interfaces."

      I might not go quite that far, but the authoes comment that it's "quirky" struck me as a bit odd. There is no "common user interface" guidance any more. No one follows what used to be there. Even MS don't follow their own CUI any more. So anything not compliant with the CUI is just different. And that is so many apps these days that nothing is really "quirky". Just different.

    5. Anonymous Coward
      Thumb Up

      Re: Upwards thumb

      Calibre doesn't only let you read books, it allows you to add notes and even edit the books yourself.

      If, for example, you collect books on Linux distros, you can copy the parts you are interested in and create your own book (and even update it as things change or you gain knowledge).

      1. Fred Daggy Silver badge

        Re: Upwards thumb

        Big thumbs up to the editing of books. Got a document you want on hand, on your kindle. Convert. However, then you can touch up the markup to get rid of the grosser conversion errors. You can go down a rabbit hole with how much to edit/touch up. But it gets the job done.

        Some formats convert better than others, of course. Mostly due to technical limitations.

        1. Steve Graham

          Re: Upwards thumb

          And the search & replace function supports regular expressions. (I'm an old Perl hacker.)

          I had one book, supposedly in UTF-8 encoding, but all the 2-byte characters were wrong -- fancy quotes, em-dashes and the like -- and I was able to search for anything between 0x00ff and 0xffff, work out what they should have been, and replace all occurrences of that character.

      2. phuzz Silver badge
        Thumb Up

        Re: Upwards thumb

        I use the epub editor a lot. Even newly published ebooks often seem to come with weird problems. Often they'll set a page margin in the CSS that results in the book only using the centre 80% of the screen on my eReader. Sometimes all the text is split across just a few html files, and I prefer to split each chapter into it's own file for quicker loading/seeking.

        It's also forced me to learn a lot of regex techniques so I can really make use of the find/replace function which was an unexpected bonus.

    6. Tams

      Re: Upwards thumb

      Mate, what are you smoking? It's very late 00s/Vista.

      To each their own, but to call it 'one of the most attractive'? You're off your rocker.

      1. PhilipN Silver badge

        Re: Upwards thumb

        Saying it is attractive is stating an opinion.

        Saying you are insolent is stating a fact.

    7. Anonymous Coward
      Anonymous Coward

      Re: Upwards thumb

      I really HATE the interface. It's the opposite of intuitive, simple, eye-friendly and 99.9% of calibre features are superfluous anyway. In fact, I use calibre for one thing, and one thing only, to convert epub and other formats into amazon azw or whatever they call it (and I only got kindle because I was 'stranded', and it was 3rd hand and cheap). And the workflow on that format conversion is the top monstrosity, I can never figure out where to find the output files, because I don't use it often enough to memorise the quirky interface. On top of which, calibre told me computer says no while on W7 when it first offered an update, because it's no longer compatible, etc, etc. Well, whatever. I feel they've taken a typical software route, when it tries to do everything, because they feel compelled to add new features and prettify it, etc.

    8. LybsterRoy Silver badge

      Re: Upwards thumb

      The one thing I'd like to see is a "Just Delete" button rather than a "send it to trash" button

  2. Mike Lewis

    Avoiding Kindle

    I use Calibre to convert the books I bought from Amazon so I can read them on the Moon+ Reader Pro app. It has a far better user interface than the Kindle.

    1. mneimeyer

      Re: Avoiding Kindle

      Second vote here for Moon+

      I love that it syncs progress across multiple devices.

    2. LybsterRoy Silver badge

      Re: Avoiding Kindle

      If you're trying to avoid Kindal try Bookeen. French, the company has been into administration a few times and p&p can cost more than the cover you're trying to buy. Not a lot of support or updates but I love mine. Main reason is it has FOLDERS and I want to organise and find by author not some weird tag.

  3. stuartnz

    Calibre's interface is definitely not the most Spartan, but it's also worth noting that the viewer app can run separately, allowing ebooks to be read without starting the main Calibre app. And there's a very helpful "support crew", led the creator and primary developers, at the forums

  4. Roger Greenwood

    Amazon not helpful

    I just tried your dowload tip and get a message "You do not have any compatible devices registered for this content. Buy a Kindle or get the free Kindle reading app."

    They really don't want you to download stuff do they? (UK)

    1. yoganmahew

      Re: Amazon not helpful

      Yeah, they really don't. The Kindle (PC) app is free, though, and once downloaded, I believe you can define the folder you want to use to store downloaded content. You used to be able to anyway.

  5. Alumoi Silver badge

    Buying consumable content online for immediate consumption

    OK, I know the downvote brigade will show up clobber me, but CAN WE STOP WITH THIS NONSENSE?

    You don't consume books/music/movies. You read/listen/watch them.

    1. Tom 7 Silver badge

      Re: Buying consumable content online for immediate consumption

      How about 'Devourables' cos thats what I do with a good book.

      1. Anonymous Coward
        Anonymous Coward

        Re: Buying consumable content online for immediate consumption

        well, in that case it means you consume them fast...

        1. DJV Silver badge

          Re: it means you consume them fast

          Yeah, and then it's a bugger to get the binding and staples out from between your teeth...

    2. ThatOne Silver badge

      Re: Buying consumable content online for immediate consumption

      > You don't consume books/music/movies. You read/listen/watch them.

      While I totally agree with you, I have to admit knowing people who indeed and really "consume" stuff much like they would drink a cool soda on a hot day: Quickly, indifferently, and without a second thought.

      So it's not really a misnomer, just a specific attitude not everybody shares (Fortunately, but that's just IMHO: YMMV and all that).

    3. Doctor Syntax Silver badge

      Re: Buying consumable content online for immediate consumption

      I'm not sure we were reading the same Wikipedia article but the one I read was contrasting consumables with durables. Food and water are given as examples but only as part of a wider range of examples. Just as well really, or else consumer protection legislation would have a very much narrower scope.

  6. DrXym

    Calibre is great

    It's a very handy way to manage ebooks. It's also not hard to find plugins that strip out DRM from books so they're no longer bound to a device, or to a service.

    1. Geoffrey W
      Black Helicopters

      Re: Calibre is great

      [*Cough*]-Apprentice Alf-[*Cough*]

      1. Colin Bull 1

        Re: Calibre is great

        Calibre along with whatever version of Linux I am using are the primary destinations for my occaisional donations.

        I do not use it as an ereader, I use it to create a library of books I have read and my rating of the author to steer future purchases and prevent duplicate purchases. ( senility has its downsides). And to remove DRM so I can share books with her indoors.

        Dedrm (for me ) requires an Adobe ADE cert or some such to work, but MANY MANY thanks to Apprentice Alf and his sidekicks for its existence and ongoing support.

        BTW to download books from Amazon you have to prove purchase of a Kindle by supplying its serial number.

    2. Charlie Clark Silver badge

      Re: Calibre is great

      Totally agree that DRM doesn't protect content, it's just about tying users to services and devices.

      I never managed to get the plugins to strip the DRM from my books propery, so I do it with Epubor and then stick them in Calibre. The interface is a bit clunky but the plugins are great: I have a Kobo so it's great that the additional features are magically supported.

      I've also used the editor to break down some omnibuses into more manageable sizes.

  7. Mrs Spartacus

    Duplication of files

    I agree with many about the interface in Calibre, it's not my favourite. I tend to use it, as several have already mentioned, to convert files, rather than read them.

    The one annoying feature I discovered is that it copies any material you point to into its own library. I use a Dropbox folder and a couple of other folders to store books, and registering them in Calibre causes a complete copy to be made of them. Once you've realized that, it can be managed.

  8. Kev99 Silver badge

    I've been Calibre for years and it is, to say the least, great. I can take practically any e-book, run it thru Calibre, and drop it onto my Kindle. Before that I was doing the same with my Palm device.

  9. Anonymous Coward
    Anonymous Coward

    Warning: The book Reader or "View" alters EPUB metadata

    I bet this can cause multiple excess backups to be created because the checksums change when the metadata changes.

    1. phuzz Silver badge

      Re: Warning: The book Reader or "View" alters EPUB metadata

      You can turn that off, but it's enabled by default, and even the Calibre ebook Editor flags the presence of the file with a warning.

      As several users point out in that bug report, something labelled a "Viewer" should be read-only by default.

  10. Anonymous Coward
    Anonymous Coward

    I already use Calibre and have done for I think I'm supposed to act smug and look down on people who are only just discovering it. that right?

    Anyway, yeah. It's great, though I find it a bit overpowered for day-to-day use. A "lite" version or ability to hide many of the functions would be appreciated one day.

  11. DomDF

    Does it support Python 3 yet? Last I checked the maintainer was going to keep it on 2 forever.

    1. DrXym

      Yes eventually it moved to Python 3. Calibre was just another victim of the incredibly ill-thought out decision to develop Python 2 & 3 in parallel for a decade rather than just ripping the plaster off and moving on.

  12. ThePendragon

    I have been using Calibre for so long I can't remember how far back

    Geez, Calibre has been around forever. It is really simple to install on any linux distro now but before it had its current installer I had to have kovid walk me through the install manually on Slackware (I now use Debian). I've also donated to Calibre several times. If you use it and find it useful I suggest you donate money.

    If you are having trouble stripping DRM off Amazon books best bet is to use an old version of kindle for pc. I emulate it in wine in linux and I'm able to strip drm off ebooks in linux with the appropriate plugins it is really a PITA to set up in linux but setting it up in windows is a challenge too because you have use a batch script or something to force kindle for PC not to update itself because it aggressively seeks to do it.

    Anyway, wow, I've used Calibre for so many years it seems like it has been around forever now. I used to use it with my old SONY readers (SONY no longer makes ereaders) now I use it mostly with a Boyue Likebook P78 with KOreader and it works like a charm.

  13. Proton_badger


    I find it to be a bit of a ponderous whale so I only use it for conversion. I prefer to manage my library with the file system and use more lightweight readers.

    It’s a good and very capable app for those who prefer it that way, just slow.

    1. DrXym

      Re: Calibre

      It is a bit slow but it's tolerable. If I were to guess I bet most of the code is written in Python and suffers from the performance problems associated with the language like the global interpreter lock. There must certain bottlenecks around IO / encryption / compression / parsing that would be benefit from optimization, e.g. rewritten as extensions.

  14. Anonymous Coward
    Anonymous Coward


    Seems a bit late to be useful in any lockdown. Haven't seen anything close to one of those here in nearly two years now.

  15. that one in the corner Silver badge

    Hate how it wants to copy and RENAME all the files

    I stopped using Calibre because it insisted on copying and renaming the ebooks, except when it decided not to because there was already a copy in another format and it decided that it would be better to let Calibre repeat the conversion from the first copy it came across rather than, say, ask or find out which copy had the best quality.

    I have the ebooks already sorted into directories that group them by purchase - a lot of Humble Bundles, for example - and it makes it nice and easy then to check things like "are there any items I've not yet downloaded from Humble?" when even the really lazy way works (kick off the downloads but click "no" when told the file already exists and do I want to overwrite it).

    Other files have names that were changed when downloaded, usually to keep the numeric file id from the original source (downloaded hardware manuals, research papers, LEGO build instructions etc) but tack on some more meaningful info as well (LEGO set number - not the same as the file id - set name, booklet number x of y; or subject matter, main authors, year published, which proceedings). All really useful info when the file is sitting on an SD card to go into one of the ereaders. Most of which is lost when you let Calibre get its hands on the file. Or some weirdness means every paper is renamed "1980 Proceedings on Ferret Wrangling" so they are all copies of the same thing and only one need be kept.

    I can see Calibre working well if you are happy to let it take over your files or you are happy to just keep two copies of everything. Maybe I'll just buy enough file server drives that the duplication seems acceptable.

    Or, best of all, you will all chime in and point out that Calibre has had a "leave my files alone" flag for years now.

    1. phuzz Silver badge

      Re: Hate how it wants to copy and RENAME all the files

      It's definitely one of those programs where you pretty much just have to do things the way it wants them to be done, or find something else.

      Fortunately for me I didn't really have a system for dealing with ebooks when I first started using Calibre so I didn't have anything to adapt.

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