PDF to MOBI: what breaks, and whether to bother

PDF to MOBI reflows a fixed page and then packs it into an old Kindle format. Scans stay unsearchable. Newer Kindles should not target MOBI. Online steps.

PDF to MOBI is two compromises at once: reflow a fixed page, then store it in an older Kindle format. Do both only for a very old Kindle that reads MOBI and nothing newer. A current device should get EPUB through Send to Kindle, or AZW3 over USB.

What the reflow does wrong is covered in PDF to EPUB. MOBI then simplifies styling again. See EPUB to MOBI.

What should you look at in the PDF first?

Open it on a computer and try to select one sentence.

  • You can select it. There is a text layer, so conversion is possible. Columns, footnotes, and headers may still land in the body. Read the result.
  • You cannot select it. It is a scan or a photo. The MOBI is still a stack of images. You cannot search it, and the file is often larger. Conversion is not OCR.

A single-column novel is the file this is good at. A two-column paper, a table-heavy manual, or an art book should stay PDF. Kindle opens PDF directly. The type just will not grow and reflow.

How do you convert it here?

After you know the device really is an old Kindle:

  1. Open MOBI converter.
  2. Drop the PDF. The limit is 50MB.
  3. Start conversion and leave the page open. An image-heavy PDF can take several minutes.
  4. Download and open it on that Kindle. Do not email the MOBI to Send to Kindle.

If the device actually reads AZW3, stop. In ebook converter, set the PDF's output to AZW3 directly. That skips the older MOBI container. EPUB to AZW3 explains the USB side once you have a reflowable file.

What does a broken conversion look like?

The contents jump to a running header, a footnote sticks in the middle of a sentence, or the left and right columns alternate one line at a time. That is a fixed page being reflowed. Converting the bad file a second time will not repair it. If a Word or EPUB original exists, convert that instead.

Common questions

Is PDF to MOBI safer than PDF to EPUB?

The mess comes from the fixed PDF, not from choosing MOBI or EPUB. Both reflow. Unless the device is a very old Kindle, EPUB or AZW3 is the more useful result. MOBI adds an older format on top.

Can I copy text from a scanned PDF after it becomes MOBI?

No. Scanned pages are pictures. Conversion does not recognize the words. The MOBI is still pictures, and you cannot search it.

Will the MOBI work with Send to Kindle?

No. That service no longer accepts MOBI. For a newer Kindle, convert the PDF to EPUB and send that, or convert to AZW3 and copy it over USB.

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