What this error means
KDP enforces a 650MB upper limit on both paperback interior PDFs and Kindle EPUB files. Files larger than 650MB either fail to upload outright or are rejected after upload with "Your file exceeds the maximum file size limit."
Most novels are well under this — a 300-page text-only paperback PDF is typically 1–5MB. The limit only bites for image-heavy books: photo books, cookbooks, illustrated children's books, art books, and academic books with hundreds of figures.
For Kindle, KDP also charges a delivery fee of $0.15 per MB (US, 70% royalty tier) above 1MB. Even at 5MB your royalty per sale drops by ~$0.75. So there's a financial reason to compress beyond just hitting the 650MB ceiling.
Why it happens
Uncompressed image embedding. Photoshop "Save as PDF" with "Preserve Photoshop Editing Capabilities" embeds full layered PSDs, multiplying file size 5–10×.
TIFF images at 600 DPI when 300 DPI is plenty. TIFFs are lossless and uncompressed; a single page-sized TIFF can be 30MB.
InDesign with linked images set to "High Quality Print" preset preserves images at maximum resolution. Switch to "Press Quality" or "PDF/X-1a" to downsample to 300 DPI.
Font embedding without subsetting. Embedding a full Unicode font (50,000+ glyphs) when you used only Latin characters adds 5–20MB per font.
Picture book EPUBs. Reflowable EPUB with high-res illustrations can exceed 100MB; fixed-layout EPUB (children's, cookbook) can easily hit 300MB+.
Embedded videos or interactive elements in EPUB. KDP doesn't support video — strip them out.
Multiple language editions packed in one file, or one EPUB containing both Latin and CJK glyphs in every font.
The fix
Step 1: Confirm file size. Right-click → Properties (Windows) or Get Info (Mac).
Step 2 (PDF: Acrobat compression). Open in Acrobat → File → Save As Other → Reduced Size PDF or Compressed PDF. Choose "Acrobat X and later" compatibility. This downsamples images to 150–300 DPI and strips redundant data. Test the output — can lose quality if pushed too far.
Step 3 (PDF: targeted image compression). Acrobat → Tools → Optimise PDF → Audit Space Usage. See which page elements are biggest. Images is usually #1, fonts #2.
Step 4: Re-export from source with compression. (InDesign): File → Export → PDF/X-1a:2001 → Compression tab → set colour images to 300 DPI, downsample using "Bicubic Downsampling", compression "JPEG", image quality "Maximum". For greyscale, same settings. Monochrome can go to 1200 DPI with CCITT Group 4 (lossless).
Step 5 (Photoshop image compression before placing). Open each large image → Image → Image Size → 300 DPI at print dimensions → Save As → JPEG Quality 9 (high but not max). Re-place in your manuscript.
Step 6 (Font subsetting). In InDesign → File → Export → PDF → Advanced → Fonts → "Subset fonts when percent of characters used is less than" → set to 100% (forces full subsetting). Cuts font weight to roughly 5–10% of original.
Step 7 (EPUB: image compression). Open in Sigil → Tools → Image Information → list shows file size per image. Compress large ones externally (use Squoosh or ImageOptim) then replace in Sigil.
Step 8 (EPUB: strip video and audio). KDP doesn't support video or audio in Kindle EPUB. Open the EPUB folder → delete any .mp4, .mp3, .ogg, .webm files → remove their references from the manifest.
Step 9: Re-verify file size. Aim for well under 650MB — ideally under 50MB for EPUB to keep delivery fees low.
How to pre-flight it
Our free KDP Readiness Score reports your file size, the size of the largest images, and an estimated delivery fee for Kindle. Plus 30+ other KDP rules in one pass.
Related errors
- KDP error: low-resolution interior images
- KDP error: embedded images too large
- KDP error: transparency not flattened
FAQ
Does the 650MB limit apply to both PDF and EPUB? Yes — 650MB is the cap for both print PDF interiors and Kindle EPUB uploads.
Will compressing images affect print quality? At 300 DPI JPEG Quality 9, no visible quality loss for photographs. Line art and diagrams should stay as vector or higher-DPI to avoid jagged edges.
Is there a smaller limit for fixed-layout Kindle? The 650MB upload limit applies, but fixed-layout files compress less efficiently. Many children's book EPUBs hit 50–200MB legitimately.
Why is Kindle delivery fee a thing? It covers Amazon's bandwidth to push the file to customers' devices. The fee only applies on the 70% royalty tier (35% tier has no delivery fee but a much lower royalty).
