Free KDP Spine & Cover Calculator
Determine precise spine widths and full cover layouts matching Amazon KDP specifications. No registration required.
Cover Specifications
KDP Cover Design Rules
- •Bleed requirements: Adds 0.125" to all outer edges (totaling 0.25" added to height, and 0.25" to combined width).
- •Barcode Safety: Keep all text/important details 0.25" away from the cover edges and 0.125" away from spine hinges.
- •Calculations are output in inches (in). Ideal DPI is 300 DPI for printing.
Calculated Measurements
Frequently Asked Questions
Why does my page count affect the cover size?
In physical books, the spine width grows or shrinks based on how many sheets of paper are bound together. Our calculator automatically adjusts the spine width using the precise sheet thickness multipliers provided by Amazon KDP.
What is "Bleed" and why is it exactly 0.25"?
Bleed is the extra print margin (0.125" on each outer edge) required by printers to ensure colors and artwork extend fully to the edge after the page is trimmed. Since bleed is added to the left and right sides of the cover, it increases the overall cover width by 0.25". Similarly, it increases the cover height by 0.25" (top and bottom).
Why can't I put text on my spine?
Books with fewer than 79 pages have extremely thin spines (under 0.17 inches). Printers cannot guarantee the alignment of text on such thin areas without it spilling onto the front or back covers, so Amazon KDP prohibits spine text for books under 79 pages.
What is the difference between Paper Types?
White and Cream paper types have slightly different physical thicknesses (Cream is thicker at 0.0025" per page vs. White at 0.002252"). Color printing uses another grade of white paper which is slightly thicker (0.002347"). Choosing the correct option ensures your spine matches the real thickness perfectly.
How to Calculate KDP Spine Width — The Official Amazon Formula
Amazon KDP calculates spine width using the physical thickness of each individual page multiplied by your total page count. The exact multiplier depends on your chosen paper type:
/* KDP Spine Width Formula */
Spine Width = Page Count × Paper Multiplier
Full Cover Width = (Trim Width × 2) + Spine Width + 0.25"
Full Cover Height = Trim Height + 0.25"
* 0.25" = 0.125" bleed on each outer edge (left + right, or top + bottom)
KDP Spine Width Reference Table — White Paper (B&W)
Pre-calculated spine widths for common page counts using the official 0.002252"/page multiplier:
| Page Count | Spine Width (in) | Spine Width (mm) | Spine Text OK? |
|---|---|---|---|
| 50 | 0.1126" | 2.86 mm | No (< 79 pages) |
| 79 | 0.1779" | 4.52 mm | Yes (minimum) |
| 100 | 0.2252" | 5.72 mm | Yes |
| 150 | 0.3378" | 8.58 mm | Yes |
| 200 | 0.4504" | 11.44 mm | Yes |
| 250 | 0.5630" | 14.30 mm | Yes |
| 300 | 0.6756" | 17.16 mm | Yes |
| 350 | 0.7882" | 20.02 mm | Yes |
| 400 | 0.9008" | 22.88 mm | Yes |
| 500 | 1.1260" | 28.60 mm | Yes |
| 600 | 1.3512" | 34.32 mm | Yes |
| 700 | 1.5764" | 40.04 mm | Yes |
| 828 | 1.8647" | 47.36 mm | Yes (max) |
KDP Paper Type Comparison — Which Should You Choose?
Amazon KDP Standard Trim Sizes — 2026
These are the most popular KDP paperback trim sizes used by self-publishers: