EPUB and PDF eBook Formats

Taylor & Francis produces two eBook formats: webPDF and EPUB. In this section, we explain why we produce two eBook formats and the benefits to both customers and authors.

PDF Format

The PDF format is a static document format created as a proprietary format by Adobe and is now an ISO standard. Our webPDF is a copy of the print file for viewing online. Its 'fixed layout' makes it identical to the print version, including layout features like columns, image placement, text boxes, graphics, special characters, and equations. The PDF eBook is displayed page by page.

EPUB Format

EPUB is a digital-native and industry-standard format designed to be read on-screen created by the International Digital Publishing Forum (IDPF) and now managed by the Word Wide Web Consortium (W3C). Its use of existing HTML standards makes it adaptable and the most accessible format for digital content – for everyone, not just those who cannot easily read text on screens or printed media. The EPUB eBook is displayed very much like a web page.

EPUB File Format

• Reading Experience: The reflowable nature of text and layout makes this format easier to read on mobile devices.
• Adaptable: Users can change fonts, text and background colors to suit their reading needs.
• Inclusive: Support for assistive technology allows for structured tagging, improved navigation, semantic identification of content, long descriptions, tables, enhanced metadata, and more.
• Interactive: Built on web technologies allows for features such as video, audio, pop-up definitions, and quizzes.
• Small size: EPUB files are up to 90% smaller than PDF files meaning faster download times and more efficient data usage for mobile users.
• Install required: Windows and Android devices usually do not come with a built-in EPUB reader even though their online stores have several to choose from (they are typically free).

webPDF File Format

• Replicable: Mirrors print layout exactly, so may work better for titles with lots of pedagogical features or where layout is important.
• Universal: Most devices come with a PDF reader already installed.
• Less accessible: PDFs support only the most basic accessibility features, lacking many of the advanced features modern screen reading software needs to provide good navigation and content identification.
• Mobile unfriendly: Users are limited to the original layout and cannot adjust font faces or sizes, forcing the user to zoom and scroll to see details on mobile devices.
• Incompatible: Large file sizes mean increased download times and more data usage.

The greatest difference between our two format types comes in the comparison of accessibility features. Accessibility in publishing is nothing new; the Americans with Disabilities Act set requirements back in the 1990s, but the upcoming European Accessibility Act increases the publisher’s responsibility.

PDFs offer the basic accessibility functions like bookmarks for navigation, structured content for navigation, content reading order, page numbering, and image alternative text inclusion. However, the fixed layout of PDF is restrictive. The print-centric nature of PDF limits content interaction to zoom and scroll, hampering low vision or neurodiverse users reading the content. The underlying document structure also lacks any form of semantic identification to help screen reading software identify the structure or purpose of content or hyperlinks. This makes it easier to "get lost" in a PDF document when using screen reading software. 

Conversely, the EPUB format offers basic accessibility functions like bookmarks for navigation, structured content for navigation, content reading order, page numbering, and image alt text inclusion. With their dynamic layout, EPUBs can easily incorporate long descriptions and video/audio transcripts where they are needed, simplifying navigation. The dynamic layout allows users to adjust the font family, font size, and font contrast ratios on the text, greatly aiding low vision or neurodiverse users.

While the PDF meets basic needs of an eBook, the EPUB has many advantages over it in terms of functionality and customer inclusion. Given the flexibility of the EPUB format and its support for accessibility, you can expect it to gradually overtake PDF as the dominant format in the eBook market.

Each eBook retailer or aggregator that hosts Taylor & Francis content provides their own eBook reader app or platform which customers can use to access eBook files. When a customer purchases an eBook via a third-party, access is through the proprietary eBook reading app or platform. Each eBook app or platform has slightly different functionality and the format of the eBook affects how the content is displayed. The display of EPUB files, for example, may differ on each eBook app or platform. 

Taylor & Francis distributes to many eBook retailers and aggregators and each one has a preferred format which works best with their eBook reader. Some third-parties accept both EPUB and Web PDF, but EPUB files are the preferred format for most of the channels we distribute to. The EPUB format works well for the majority of Taylor & Francis titles, and it is our preferred format due to its digital accessibility functionality.

Occasionally, we may make exceptions to the EPUB format and opt to produce webPDF only instead. This only happens when the title contains specific layouts which may not render accurately in common EPUB readers in the market.

Customer devices are normally enabled to read a PDF and may come with installed EPUB reading software. Many of our eBook retailers and aggregators enable EPUB or PDF access on their reading platforms. On occasion, users may need to install additional software in the form of either an App or a browser extension to read PDF or EPUB. Taylor & Francis uses Acrobat Reader to review or webPDF content and Thorium Reader to review our EPUB content ahead of publication. Many EPUB readers are free.

Taylor & Francis is committed to providing an inclusive experience for all our readers, to help those readers reach their highest potential. One of the steps we've taken to make our books more accessible is to publish them in the EPUB file format, wherever possible.