Calibre 9.16 Adds Kokoro Read-Aloud Voices, AVIF Images, and Newer Kobo Support

What changed in Calibre this month? Calibre's what's-new page opens with Release 9.16, dated 09 Oct, 2026. The notes are a list of features and fixes. For authors who keep a library, convert files, or listen while they proof, four items change the daily tools: new read-aloud voices, AVIF images, PDF import, and a Kobo driver update.

Read aloud gets Kokoro voices

Under new features, the page says: "Read aloud: Add the high quality Kokoro voices, which sound much more natural than the Piper voices, especially for English."

The setup is specific. "To use them, select the Piper backend in the Read aloud configuration and choose one of the Kokoro voices. The voice will be automatically downloaded the first time it is used."

The notes do not say how many Kokoro voices ship with the release, which languages besides English improved, or how large the download is. They do say the Piper backend is where you select them.

AVIF images and PDF import

A separate bullet says: "Add support for reading images in the AVIF format."

The notes do not say which ebook formats can hold those images, and they do not mention any retailer. The change, as written, is that Calibre can read AVIF images.

PDF Input, in the same release, gains "Support for right-to-left text and better handling of multi-column pages."

PDF Output has two fixes in the bug list. One: "Fix some trailing content at the end of individual HTML files being lost when the files use multi column layout." The other: "Fix a regression in 9.x that caused conversion of some books with vertical writing to not work correctly."

Editing the book and the viewer

Edit book gets three notes:

• "Check book: Allow skipping of problems of a particular type."
• "ToC View: Indicate what ToC entries, if any, are in the file being currently edited."
• "Check book: When auto fixing invalid ids also update CSS selectors."

The viewer gets three of its own:

• "Add an option to display the immediate parent ToC section in headers/footers."
• "Allow e-books to store up to 1MB of data persistently."
• "Print to PDF: Allow specifying margins in metric units."

The page does not say what that 1MB of stored data is for. It states the limit.

Other library tools in the same list: tag mapper and HTML/CSS transform rules can be searched; individual entries can be removed from the search history dropdown; and Preferences, Look & feel, Main interface gains a button "to reset the main window layout." The tag browser gets "a new option to sort hierarchical tags that have only children but no actual books as folders, before all other tags at their level."

Devices, conversion, and news downloads

"Kobo driver: Add support for newer firmware." The notes do not name the firmware versions or the device models.

"DOCX Output: Make images inside links clickable." A related fix says: "DOCX Output: Fix non-breaking spaces not being preserved."

Another line: "Speed up various operations on large libraries, such as startup, deleting many books, sorting by series, searching and refreshing the Tag browser."

News download: "Support for downloading news from websites that block automated access by using the camoufox browser." The page names The New York Times, The Economist, and The Atlantic as examples of sites that "block all lighter weight ways of fetching their pages." Recipes for those sites "now use the camoufox browser, which is automatically downloaded the first time such a recipe is run." People who write recipes "can use it by setting browser_type = 'camoufox' in their recipes."

Create your own Adventure, the feature added in Release 9.15 on the same page, gains "Allow exporting and importing saved games" in 9.16. The 9.15 note says that feature "is completely optional and not even loaded unless you explicitly run it."

The release also lists fixes for EPUB 3 conversions ("Preserve ids on nav elements so links to them continue to work"), FB2 metadata clearing, a viewer clash between dark mode and image filters, and "Content server: Various security hardening fixes."

Why it matters for authors

Proofing by ear has a new voice path. If you use Calibre's read aloud to hear a manuscript, the notes say Kokoro voices sound much more natural than the Piper voices, especially for English. You still select them inside the Piper backend, and the voice downloads the first time you use it.

AVIF is now a format the program can read. The bullet is one line. If an image in your files is AVIF, 9.16 is the release that adds support for reading it. The notes do not say Calibre will convert those images for any store.

PDF in and PDF out both moved. Import now claims better handling of right-to-left text and multi-column pages. Export fixes a case where trailing content was lost from multi-column HTML, and a 9.x regression with some vertical writing.

Kobo sideloading depends on the driver. If a newer Kobo firmware stopped talking to Calibre, the notes say 9.16 adds support for newer firmware. They do not list which versions.

Check book can ignore one kind of problem. If the same warning fires on every file and you already know it is not a real error, 9.16 lets you skip problems of a particular type. When it auto-fixes invalid ids, it also updates CSS selectors.

Sources

• calibre: What's new (Release 9.16, 09 Oct, 2026)