PDF too big for Kindle
Send to Kindle takes PDFs up to 200 MB on its website and 50 MB in total by email. A scanned book that is over either limit shrinks most when its grey page photos become clean black-and-white pages.
Key takeaways
- Amazon's limits: 200 MB through the Send to Kindle website, 50 MB in total per email. We found no figure from Amazon for the apps.
- Scans are big because every page is a photo, often in colour or grey, at high resolution.
- Squeezing those photos harder makes the file smaller and the text blurry. Turning text pages into black and white shrinks them without that.
- In one production run on 2 Nov 2026, a 300-page book came out at about 9 MB with every page searchable.
- Splitting the book into parts gets it under the limit too, but you lose one-file search and your place across parts.
The limits, route by route
Checked on Amazon’s pages on 4 Nov 2026.
| Route | Largest PDF | Source |
|---|---|---|
| Send to Kindle website | 200 MB | Amazon |
| Email to your Kindle address | 50 MB in total, up to 25 attachments | Amazon help |
| Send to Kindle apps (phone, Mac, Windows) | No figure from Amazon | iOS, Android, Windows, Mac |
| USB cable | No Amazon limit found | Handwriting not supported on Scribe PDFs loaded this way (Amazon help) |
Your email provider may also cap attachments below Amazon’s 50 MB, so a file that fits Amazon’s limit can still bounce from your outbox.
Why a scanned book is so heavy
A PDF made from typed text stores letters, a few bytes each. A scanned PDF stores a picture of every page. How heavy that picture is depends on three choices made at scanning time:
- Colour mode. A colour scan of a page of plain black text records the tint of the paper, the yellowing, the show-through, all in three colour channels.
- Resolution. Library and archive scans are often made at high resolution for preservation, far beyond what a 6-inch screen shows.
- Compression. Photos are saved as JPEG or similar, which is good for photos and wasteful for black type on paper.
Multiply that by 400 or 600 pages and a book passes 200 MB without anything being wrong with it.
Three ways to get under the limit
| Method | Size | Text quality | The catch |
|---|---|---|---|
| Recompress the images harder | Smaller | Softer, with blur and blotches round letters | Thin type and small print suffer first |
| Split the book into parts | Each part fits | Unchanged | Search and bookmarks stop at the end of each part |
| Clean to black and white | Much smaller | Sharper | Picture pages stay grey and take more room |
Recompressing
This is what most “compress PDF” buttons do: they lower the image quality or the resolution until the size drops. On a scanned book you see it as fuzzy edges on letters and grey smudges in the white space. The free tiers also have their own caps: iLovePDF compresses files up to 300 MB for free, while Sejda stops free files at 50 MB.
Splitting the book
You can cut the book into two or three PDFs that each fit. It works, but each part is a separate document on your Kindle, a search only covers the part you’re in, and you have to remember which part you were reading.
Cleaning to black and white
For a page of text, the only thing that matters is where the ink is. Once the paper is levelled to white and the print turned to solid black, each pixel needs one bit, not 24, and long runs of white compress to almost nothing. FixMyScan stores these pages losslessly, so the letters stay exactly as cleaned, with no blur added to save space.
Pages that carry photos, maps or engravings are kept in greyscale so the pictures survive. A book full of plates will come out larger than a plain novel of the same length.
One real example
On 2 Nov 2026 we ran a 300-page book through the live service. It went in at about 13 MB and came out at about 9 MB, with every page cleaned and searchable. That input was already fairly small. A grey archive scan of the same length would have more to lose. We don’t quote a typical saving, because we haven’t measured enough books to give one.
Steps
- Check the size. Our will it fit check compares your file with each route’s limit.
- Upload the book to FixMyScan. PDF or DjVu, up to 1,000 pages.
- Set one crop to remove margins and dark edges across every page.
- Download the cleaned PDF and check its size.
- Send it. Under 50 MB, email works. Under 200 MB, use the Send to Kindle website. If it still fails, see Send to Kindle not working.
Questions
What is the maximum PDF size for Send to Kindle?
200 MB through the Send to Kindle website, and 50 MB in total per email, with up to 25 attachments, per Amazon's help page.
What about the Send to Kindle app on my phone or computer?
Amazon's app pages don't give a figure. Some guides say 200 MB, but we haven't seen Amazon confirm it, so plan around the website limit.
How do I make a PDF file smaller so I can email it?
For a scanned book, turn the text pages into clean black and white and crop off the margins. That removes most of the data while keeping the text sharp. Generic compressors mostly lower the image quality instead.
Can I just zip the PDF?
Amazon accepts ZIP files by email, but zipping a scan rarely saves much, because the page images inside a PDF are already compressed.
Can I copy a big PDF over USB instead?
Yes, on a Kindle that takes files over USB. On a Kindle Scribe, Amazon says handwriting isn't supported in PDFs loaded over USB-C, so that route costs you note-taking.
Why did OCR make my PDF bigger?
Some tools rebuild every page image when they add text, and save it larger than before. The text itself adds little. FixMyScan writes the cleaned page once and puts the text under it.
Will the pictures in my book get blurry?
Pages with photos or engravings are kept in greyscale, so they take more room than text pages, but they aren't reduced to black and white.
How do I check whether my file will fit?
Our free will it fit check compares a PDF with each limit in your browser.