The E-book viewer

calibre includes a built-in E-book viewer that can view all the major e-book formats. The E-book viewer is highly customizable and has many advanced features.

Starting the E-book viewer

You can view any of the books in your calibre library by selecting the book and pressing the View button. This will open up the book in the E-book viewer. You can also launch the E-book viewer by itself from the Start menu in Windows. On macOS, you can pin it to the dock and launch it from there. On Linux you can use its launcher in the desktop menus or run the command ebook-viewer.

Customizing the look and feel of your reading experience

You can change font sizes on the fly by using Font size in the viewer controls or Ctrl++ or Ctrl+- or holding the Ctrl key and using the mouse wheel.

Colors can be changed in the Colors section of the viewer preferences.

You can change the number of pages displayed on the screen as well as page margins in Page layout in the viewer preferences.

You can display custom headers and footers such as time left to read, current chapter title, book position, etc. via the Headers and footers section of the viewer preferences.

More advanced customization can be achieved by the Styles settings. Here you can specify a background image to display under the text and also a stylesheet you can set that will be applied to every book. Using it you can do things like change paragraph styles, text justification, etc. For examples of custom stylesheets used by calibre’s users, see the forums.

Dictionary lookup

You can look up the meaning of words in the current book by opening the Lookup/search panel via the viewer controls. Then simply double click on any word and its definition will be displayed in the lookup panel.

Copying text and images

You can select text and images by dragging the content with your mouse and then right clicking and selecting “Copy” to copy to the clipboard. The copied material can be pasted into another application as plain text and images.

Non re-flowable content

Some books have very wide content that content be broken up at page boundaries. For example tables or <pre> tags. In such cases, you should switch the viewer to flow mode by pressing Ctrl+m to read this content. Alternately, you can also add the following CSS to the Styling section of the viewer preferences to force the viewer to break up lines of text in <pre> tags:

code, pre { white-space: pre-wrap }