How to Format PDF Files for the iPad and Other E-readers

Ever since I launched The Illustrated Section, I have been getting a ton of questions by creators about what is the best size and resolution for PDF files intended for e-readers. Here’s some answers to these questions.

Think iPad

If you’re not designing for a specific device, I recommend you design your book for the iPad. Of the popular e-readers, it has the largest screen. If you format for the iPad it will look good on other smaller devices too, and you cover more bases that way.

Image Resolution

First, it’s good to know the size of the device you are formatting for. The iPad screen is 1024×768 pixels. That means your images should be close to or bigger than this size if you don’t want them to look blurry.

For example, a page of my comic My Sister, the Freak is 7″x10″. When I formatted the PDF, I made the images 100 dpi so the pixel dimensions were 700×1000 pixels.

You don’t have to go much bigger than that. Even though my page size is technically smaller than the iPad screen, it looks great and the reader can even zoom in a little without it looking too pixelated.

My opinion for ebooks is you want to create an experience that is just slightly better than viewing your comic or book on the web (a standard web image is 72 dpi). For that, you don’t need a super high resolution. I generally recommend somewhere between 100-150 dpi depending on the size of your pages. Anything over that is probably overkill. It will make your file sizes unnecessarily large, which will make them tougher to download and read.

Page Dimensions

Another thing to take into account is the ratio of the height and width of your pages. You want to avoid anything extremely wide or extremely tall, because they will appear small when fit onto the screen, and will require lots of zooming and scrolling in order to read them. This could especially be a problem for picture books, which are often horizontally oriented and contain full page spreads.

That being said, I have found that your pages can be fairly wide/tall before it starts being super inconvenient. Just make sure your text is large enough to read and your images are clear when zoomed out.

Will Terry’s Monkey & Croc, for example, is made up of fairly wide horizontal spreads, but still looks great on the iPad.

Multiple Page Sizes

A typical comic or picture book might be best viewed one page at a time, but what if you have a couple pages you want viewed together as a full page spread? Or what if you have one or two horizontal pages in a mostly vertical book?

I advise to simply make your pages as they are intended to be viewed. Combine multiple pages in a spread together as a single page. And use whatever page size if best for each individual page. The beauty of digital books and PDFs is that every page doesn’t have to be the same size. Also, most e-readers are flexible enough to handle change in vertical/horizontal orientation where the reader just needs to push a button or turn the device to flip the screen.

If you’re afraid that making the reader flip or zoom in on the page might be inconvenient for them, I generally think it is not a big deal if it doesn’t happen too often during the course of the book. If you’re switching every other page however, then maybe consider changing the page size/design of your entire ebook.

Rotating Pages

One more tip – I have run across a few ebooks that have horizontal pages or spreads rotated in order to fit on vertically designed e-reader screens. I advise against this. Like I said above, most e-readers are smart and flexible enough to handle change in orientation and size. Rotating the images yourself will work against that, often to frustrating results. For example:

    Here is a horizontal page.

    The iPad is a vertical screen.

    This is what the page looks like on that screen.

    The creator thinks it would be smart to rotate the image to fit on the screen better. The reader buys the book and tries to read it. The file opens up and it looks like this:

    So the reader rotates the iPad so they can read the page. But guess what? The iPad detects this and… rotates the page again. It turns out the reader can’t read the book at all unless they turn their neck and read it sideways.

This might not be an issue for all devices, but you never know how your reader is going to read your PDF or if their screen is horizontal or vertical. Just leave the images as they are and how they’re intended to be read.

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19 Responses to How to Format PDF Files for the iPad and Other E-readers

  1. Aaron says:

    Thanks for the info, I was deciding between 100 and 150 dpi. I plan to make my images 700×1000 so if 100 dpi works I’ll go with that. I wish I had an iPad or something tablet related to test it out, but I trust ya Dani. lol

  2. Jhay Phoenix says:

    Good stuff…can’t wait to format content for the iPad…one day.

  3. diana Delosh says:

    Good info – haven’t had to do 1 yet -but you never know!

  4. diana Delosh says:

    Just curious – Can E-Books be any number of pages? As opposed to traditional print books which are usually 32 pages and multiples of 8?

    • Dani Jones says:

      Books are multiples of 8 because of the way they are printed and bound, so yes, PDFs do not have those restrictions and can have as many pages as you want. The only thing to consider maybe is if you want to print your digital book in the future.

  5. Mike Jasper says:

    Hey Dani — you can lock the screen orientation on your iPad to keep the iPad from trying to display IN MAPS & LEGENDS sideways. We’ve had issues with this pop up for our horizontal-oriented comic.
    To lock the iPad screen orientation:
    1. Hold the iPad horizontally.
    2. Double-click the Home button at the bottom of the iPad to bring up the task switcher.
    3. Swipe right on the task switcher at the bottom to bring up the iPod and iPad controls.
    4. Tap the Orientation Lock button (pictured to the right) to lock the orientation to horizontal.
    5. Press the Home button to exit.

  6. Will Strong says:

    Thanks for posting all this info Dani. I’ve been looking for information on this topic and it is surprisingly difficult to get straight answers. I’d be glad to read any similar posts.

  7. great post, Dani! I’d been searching for this info on my own – your primer really helped out (tip of the hat to @bsamuelson on Twitter for letting me know about this article.)

  8. The only decent article on the size and resolution of ebooks, thanks guys!

  9. Bill says:

    Dani this is very helpful! I’ve been playing around with a free tool called MobiPocket Creator to try to get the hang of e-publishing children’s picture books. I don’t know if I’ll ultimately use it but it allows me to test and see how the doc renders without creating an actual book on-line. I’ve had such ugly results dealing with text (word flow issues, text can’t be on images) that I’m considering going with images instead of text by creating the pages with a graphic tool (text & images) and not using Word. I’ve tested this in using vectors for the text and saving the images in the PNG format – 1800 x 1200 at 150 DPI and it looks good at any reasonable size. What are your thoughts on rendering picture book pages as just images?

  10. Terry says:

    Very cool site. Some great information for the ebook newbies like myself.

  11. Bagels says:

    For that last bit, you can always double-click the home button on the iPad and lock the screen’s rotation! Then you’d just have to swipe up and down instead of side-to-side when it’s horizontal.

  12. Luis says:

    Dani – This is great. You’ve really covered every detail and nice illustrative work also!

    Love the note “The iPad screen is 1024×768 pixels” this means 7.68 x 10.24 (in inches) which can be simplified/standardized to 7.5″x 10″ also in keeping the iPad margin equidistant on vertical view ; I’m working on an image driven interactive brochure to PDF and SWF for which the print file was 7.25×10.25(monarch) and this would in turn be in the same realm, your input confirms that. This is great news for our work-flow.

    What are your thoughts on vertical vs horizontal in terms of an ‘ideal’ or ‘universal’ best on e-readers? Traditionally there was the inclination for horizontal onscreen (desktops+laptops); This has fairly recently changed since we hold orientation of our screen in our hands literally; One recommendation I have seen is having both formats and each can be viewed based on user preference. This makes a whole lot of sense, yet as we know this adds quite a bit of labor, which in illustrated books I think can be almost astronomical depending on the actual composition. Do you think something closer to a square format has a transcendent value in the realm of e-readers (focusing on the end-user experience)?

    Lastly, I highly recommend Adobe’s Indesign for interactive PDF adaptation for anyone in your arena (which is probably what you use, but I imagine other individuals may benefit). Indesign CS5 provides the capability to export (the same file, with the same settings) to SWF; Adding bitmapping, whereas the user can experience page curling as one example. Kind of a nice feature (there are many others); It does use more memory of course, which is counter-intuitive when it comes to external devices/e-readers (vs a crisp fast pdf) but the files are optimized enough for a reasonable size. (and no I don’t work for Adobe, I’m just a satisfied graphic designer) :)

    Thanks again!

    • Dani Jones says:

      Thanks Luis. I think creators should use vertical or horizontal layout depending on what works best for their story. That’s what’s so great about e-readers – most of them are flexible enough to handle whichever format. That being said, it is my feeling that most e-readers are vertical by default, because they usually try to emulate the feeling of a real book.

  13. Tina says:

    can you please clarify about horizontal format? ….. if my ebook is horizontal format – should i lay it out 10″ wide and 7″ tall at 100-150 ppi? seems your initial example says that it will get turned on its side? so what would the correct dimensions be for a horizontal page format?
    thank you for your excellent site.
    also, what is the best way to view my pdf on my imac at the actual size it will be on an ipad – i made a 10×7 pdf file and changed my screen resolution to 1024×768, but the image on screen is still larger then actual 10×7. (the pdf is made from indd with downsampling to 100 ppi) i want to determine font size by viewing is in actual size…..or perhaps you can recommend font size for large appearance.

    • Dani Jones says:

      Yes, lay out your pages horizontally at 10″x7″. In the tutorial, I am only pointing out that I prefer that the creators don’t rotate horizontal pages sideways to fit on a vertical screen, because the user can do that on their own.

      I’m not exactly sure what you mean by the second question. If it looks ok on an iPad, it should look fine on a computer screen.

  14. lashaun white says:

    I have been trying to figure this out for over a year now.. this is a blessing to find this ! Look out for my Aware Kids book series ! Good luck to you all!

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