KDP PDF Formatter: Resize to Amazon Paperback Trim Size

Upload your PDF, pick the trim size and bleed: each page is scaled and centered without distortion for KDP.

Resizing a PDF for a KDP paperback: trim size, bleed and margins

The tool rebuilds every PDF page at the chosen trim size (6 × 9 inches by default) and places the original page on it, scaled without distortion and centred. With the bleed option the page gets 0.125 inch more width and 0.25 inch more height, as Amazon KDP requires (6.125 × 9.25 inches for a 6 × 9 book).

How the scaling works

Scale = min(target width ÷ source width; target height ÷ source height). The content keeps its proportions and the leftover space becomes two equal white bands. Available sizes: 5 × 8, 5.25 × 8, 5.5 × 8.5, 6 × 9, 7 × 10, 8.5 × 11 and A4 (8.27 × 11.69 inches), all on KDP's paperback trim size list.

Example: a US Letter manuscript to 6 × 9

An 8.5 × 11 inch page gets a scale of min(6 ÷ 8.5; 9 ÷ 11) = 0.706. The content fills 6 × 7.765 inches, leaving a 0.618 inch (15.7 mm) white band at the top and bottom. Text set in 11 pt prints at roughly 7.8 pt. From A4 the scale is 0.725 and the bands shrink to 0.259 inch (6.6 mm). A PDF already at 6 × 9 is enlarged about 2% (scale 1.021) to fill the 6.125 inch bleed width.

What the tool does not do

  • It adds no margins: if the original text runs close to the edge, it may fall short of KDP's minimums (inside margin 0.375 inch for 24 to 150 pages, up to 0.875 inch for 701 to 828 pages; outside margin at least 0.25 inch without bleed and 0.375 inch with bleed).
  • It centres every page the same way, with no odd/even page handling.
  • It does not check page count, font embedding, image resolution or the cover.
  • It targets paperbacks, not Kindle ebooks.

The PDF is processed in the browser with the pdf-lib library.

Sources and dates: Amazon KDP Help, paperback trim size, bleed and margins page (trim sizes, 0.125 inch bleed, minimum margin table, 24 to 828 pages in black ink on white paper) (checked 14/10/2026).

Frequently Asked Questions

What PDF size should I upload to KDP for a 6 × 9 book with bleed?

6.125 × 9.25 inches: KDP adds 0.125 inch at the top, bottom and outside edge, so 0.125 inch of width and 0.25 inch of height. Without bleed the PDF must be exactly 6 × 9 inches.

Why do white bands appear after conversion?

The tool keeps the original page proportions. A US Letter page (8.5 × 11) brought to 6 × 9 is scaled to 70.6% and leaves 0.618 inch of white at the top and bottom, because its width-to-height ratio differs from the target size.

Will the text get smaller after resizing?

Yes, when the source is larger. Going from US Letter to 6 × 9 applies a 0.706 factor, so an 11 pt font prints at about 7.8 pt. To keep readable type, lay the manuscript out at 6 × 9 in the first place.

Does the tool add the inside margins KDP requires?

No, it adds no margins. KDP requires an inside margin of at least 0.375 inch up to 150 pages, 0.5 inch from 151 to 300 pages and more beyond. Check that your content respects these values before converting.

Is this tool really free?

Yes, all tools on Kristools are 100% free and accessible without registration.

Is my data protected?

Yes. All processing is performed directly and securely inside your browser. No personal data is sent to our servers.