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Generation Settings

In Generation Settings, you can control aspects of the files created during Book Generation.

Accessing Generation Settings

You can access Generation settings by going to the Vellum menu and selecting Settings:

The Settings command shown in the Vellum menu

Note: In macOS versions prior to Ventura, this will be labeled as Preferences

Select the Generation tab to find the available controls:

The Generation Pane in the Settings dialog


For Kindle, you have control over how Vellum resizes images for ebooks and the types of ebook files Vellum generates.

Kindle Image Sizing

Vellum resizes and reformats images for every ebook platform. For Kindle, you can decide whether you prefer images with Higher Quality or Smaller Size:

Higher Quality
Vellum resizes images so that a full-width image is no more than 1200 pixels wide. Images are optimized with high-resolution devices in mind, with a small amount of compression to decrease file size.
Smaller Size
Vellum resizes images so that a full-width image is no more than 800 pixels wide. More aggressive compression is used to help further reduce file size and delivery costs.

Kindle Ebook Formats

Vellum can generate Kindle ebooks in both epub and mobi formats. When generating, you can choose between:

  • EPUB Only

By default, Vellum generates EPUB Only. When you’re ready to publish your ebook, Amazon requires uploading a file in this format.

Before you upload, you can proof your Kindle epub using Amazon’s Kindle Previewer. If you want to sideload your ebook onto a Kindle — for your own testing or to send to an advance reader — you can also use an epub file with Amazon’s Send to Kindle utility.

If you still need a file in the mobi format, you can generate this additional file using the EPUB + MOBI option.

Generic Ebook Format

For Generic output, you can control whether Vellum generates an EPUB 2 or EPUB 3 file:

Vellum defaults to this older version of the EPUB format, as it offers better compatibility across platforms.
This newer version of the EPUB format includes more information for accessibility and can support features like popups for endnotes and footnotes. Some stores may not accept this format, however.

Folder & Filename

The options in this section allow you to customize the folder and filename for your generated output.

Folder & Filename detail in Generation Settings

By default, Vellum will include your book’s subtitle, if any, in the folder name. To prevent this, turn off Include book subtitle.

Enable Append date if you would like Vellum to add the generation date to the output filename — e.g., My-Book-Kindle-2023-07-10.epub.