Ebook Converter
You bought or downloaded a book and your e-reader refuses to open it — almost always because the file is in the wrong format. FluidConvert converts between EPUB, MOBI, PDF, AZW and other ebook formats instantly in your browser, free and with no account.
Drop your file here, or browse
Accepts: .epub, .mobi, .pdf, .azw, .azw3 · Max 1GB · always free
Uploads use TLS encryption. Server outputs are temporary and deleted after one hour. Download your result to keep it.
Choose your ebook file, then select an output format: EPUB, MOBI, PDF, AZW3, TXT.
Fast & Free
Convert files up to 1GB free with no account. Processing limits depend on the format and file contents.
Secure
Uploads use TLS encryption. Supported image conversions can run in your browser.
Check Your Result
Quality, transparency, and supported features depend on the output format. Keep your original file.
How to use Ebook Converter
Upload Your File
Choose your ebook file using the upload area. The maximum file size is 1GB; processing also depends on your device and the file's contents.
Check the Output Format
After choosing a file, select EPUB, MOBI, PDF, AZW3, TXT under Convert to, then click Convert Now.
Download Your File
Download the result in your selected format. Open it to check the content and keep your original file.
About Ebook Converter
Why your e-reader rejects certain books
Ebook formats are tied to ecosystems. EPUB is the open standard supported by Apple Books, Kobo, Google Play Books, and most readers — but older Kindles historically didn't accept it. MOBI and AZW/AZW3 are Amazon's Kindle formats. PDF is universal but fixed-layout, so text doesn't reflow to fit smaller screens. When a book won't open, it's usually because you have an EPUB and a device that wants MOBI, or vice versa — converting bridges the gap.
Which format does your device need?
Convert to EPUB for Apple Books, Kobo, Nook, Google Play Books, and the broad majority of e-readers and reading apps. Convert to MOBI or AZW3 for older Kindle devices that don't accept EPUB. Convert to PDF when you want a fixed page layout for printing or reading on a large screen, accepting that text won't reflow on small devices. Matching the format to your specific reader is the whole game.
Reflowable vs. fixed layout
EPUB and MOBI are reflowable: the text rearranges to fit any screen size and font choice, which is why they're comfortable on phones and e-readers. PDF is fixed-layout: every page looks exactly as designed, ideal for textbooks, comics, and documents with precise formatting, but awkward on small screens because you often have to zoom and pan. Converting a PDF to EPUB makes it reflow, while converting an EPUB to PDF locks the layout — choose based on how and where you'll read.
How FluidConvert handles it
Ebooks convert in seconds on secure cloud servers, preserving chapters and text. Files are encrypted in transit and deleted automatically after conversion — your library stays private and is never stored.
When to use Ebook Converter
- Converting an EPUB to MOBI so it opens on an older Kindle
- Turning a Kindle MOBI/AZW book into EPUB for Apple Books or Kobo
- Converting a PDF textbook to EPUB so the text reflows on a phone
- Saving an ebook as PDF for printing or fixed-layout reading
- Standardizing a mixed ebook library into EPUB for one reading app
Frequently Asked Questions
How do I get an EPUB onto my Kindle?
Older Kindles need MOBI or AZW3 rather than EPUB, so convert the EPUB to one of those formats first. (Newer Kindle software accepts EPUB via Send-to-Kindle, but converting guarantees it opens on any Kindle.)
What's the most widely supported ebook format?
EPUB. It's the open industry standard and works on Apple Books, Kobo, Nook, Google Play Books, and nearly every reading app — the safest choice for everything except older Kindles.
Should I convert my ebook to PDF?
Only if you want a fixed page layout for printing or reading on a large screen. PDF doesn't reflow text, so on phones and e-readers you'll have to zoom and pan. For comfortable small-screen reading, EPUB or MOBI are better.
Will converting keep the chapters and table of contents?
Converting between reflowable ebook formats (EPUB and MOBI) preserves chapters and navigation. Converting to or from PDF can change how navigation works, since PDF handles structure differently from dedicated ebook formats.
How large an ebook can I convert?
Up to 1GB per file, free and unlimited — far more than any text-based book, and enough for image-heavy ebooks and illustrated PDFs.