KDP spine width calculator. 0.002252 white, 0.0025 cream.
Amazon's official KDP spine width formula in a free calculator. Enter your page count and paper type, get an exact spine width in inches, millimetres, and 300 DPI pixels. Includes the 80 page spine-text rule check, hardcover case laminate, and all four KDP paper types.
The official KDP spine width formula
Spine Width = Page Count × Paper Thickness
- White paper: 0.002252 inches per page
- Cream paper: 0.0025 inches per page
- Standard color: 0.002252 inches per page
- Premium color: 0.002347 inches per page
- Hardcover case laminate: the paper's thickness + 4.8 mm (0.189 inches)
The official KDP formula
Spine Width = Page Count x Paper Thickness
Hardcover: + 4.8 mm (0.189") for the case
White paper and standard color use 0.002252 inches per page. Cream uses 0.0025. Premium color uses 0.002347.
Your book details
Enter page count and choose binding and paper.
Allowed range for this binding and paper: 24 to 828 pages.
Most common KDP paper. Used for novels and non-fiction.
Calculation breakdown
200 x 0.002252 = 0.4504"
Your spine width
Print-ready values in three units.
Spine width (paperback)
0.4504"
Use this value when laying out your full cover spread.
Inches
0.4504"
Millimetres
11.44 mm
Pixels @ 300 DPI
135 px
Spine text is allowed
At 200 pages your spine is wide enough for a title and author name. Keep spine text 0.0625" (1.6 mm) from each spine edge.
The KDP spine width formula, explained.
Amazon publishes one formula for every KDP paperback and hardcover. The only variable that changes between paper types is the paper-thickness multiplier. A paperback adds nothing to it; a hardcover adds a fixed 4.8 mm (0.189 inches) for the case.
Formula
Spine Width = Page Count × Paper Thickness
Hardcover: + 0.189" (4.8 mm) for the case
Worked example: 100 pages, white paper, 0.002252 per page
Page count = 100
White paper thickness = 0.002252"
Spine width = 100 × 0.002252 = 0.2252"
That is 5.72 mm, or 68 pixels at 300 DPI.
Why 0.002252?
0.002252 inches is the measured caliper thickness of KDP's 60 lb white uncoated paper, supplied by Amazon's print partner. Rounding to 0.0023 or substituting 0.0025 produces a spine width that does not match the printed book. Use the exact value.
Why + 4.8 mm on a hardcover?
A hardcover spine is the page stack plus a fixed 4.8 mm (0.189 inches) for the case, which KDP's cover calculator adds for every hardcover. A paperback spine is the page stack alone: adding 0.06 inches to it makes the spine wider than KDP's template.
The arithmetic is identical for every paper type. Swap the multiplier: 0.002252 for white paper or standard color, 0.0025 for cream, 0.002347 for premium color. For hardcover case laminate, add 0.189 inches to the result.
KDP paper-thickness multipliers.
All four paper-thickness constants Amazon publishes for KDP, plus the hardcover case. Match the row to your interior selection in the KDP dashboard.
| Paper type | Inches per page | Notes |
|---|---|---|
| White (paperback) | 0.002252" | Most common |
| Cream (paperback) | 0.0025" | ~11% thicker than white |
| Standard Color | 0.002252" | Same paper as white |
| Premium Color | 0.002347" | Thicker white paper |
| Hardcover Case Laminate (white) | 0.002252" + 0.189" | Paper + 4.8 mm for the case |
Cream paper is roughly 11 percent thicker than white. A 400 page book is approximately 0.099 inches wider on cream than on white. Always recalculate if you change paper type after the cover is designed.
Spine width for common KDP page counts.
The fastest way to verify the formula. Each card shows the full arithmetic: page count multiplied by paper thickness, plus the 4.8 mm case on a hardcover.
20 pages
White
20 × 0.002252
0.0450"
Below KDP minimum (24 pages)
50 pages
White
50 × 0.002252
0.1126"
No spine text (under 80 pages)
75 pages
White
75 × 0.002252
0.1689"
No spine text (under 80 pages)
100 pages
White
100 × 0.002252
0.2252"
Spine text allowed
150 pages
White
150 × 0.002252
0.3378"
Spine text allowed
200 pages
White
200 × 0.002252
0.4504"
Spine text allowed
300 pages
White
300 × 0.002252
0.6756"
Spine text allowed
400 pages
White
400 × 0.002252
0.9008"
Spine text allowed
200 pages
Cream
200 × 0.0025
0.5000"
Spine text allowed
300 pages
Cream
300 × 0.0025
0.7500"
Spine text allowed
75 pages
Hardcover
75 × 0.002252 + 0.189
0.3579"
No spine text (under 80 pages)
300 pages
Hardcover
300 × 0.002252 + 0.189
0.8646"
Spine text allowed
KDP spine width chart, every 25 pages.
Every spine width KDP accepts, in increments of 25 pages, across all four paper types and hardcover. Values are total spine width in inches; the hardcover column is white paper plus the 4.8 mm case. Each cell is also valid as a print-ready measurement at 300 DPI.
| Pages | White (0.002252) | Cream (0.0025) | Standard Color (0.002252) | Premium Color (0.002347) | Hardcover (0.002252 + 0.189) |
|---|---|---|---|---|---|
| 24No spine text | 0.0540" | 0.0600" | n/a | 0.0563" | n/a |
| 50No spine text | 0.1126" | 0.1250" | n/a | 0.1174" | n/a |
| 75No spine text | 0.1689" | 0.1875" | 0.1689" | 0.1760" | 0.3579" |
| 100 | 0.2252" | 0.2500" | 0.2252" | 0.2347" | 0.4142" |
| 125 | 0.2815" | 0.3125" | 0.2815" | 0.2934" | 0.4705" |
| 150 | 0.3378" | 0.3750" | 0.3378" | 0.3521" | 0.5268" |
| 175 | 0.3941" | 0.4375" | 0.3941" | 0.4107" | 0.5831" |
| 200 | 0.4504" | 0.5000" | 0.4504" | 0.4694" | 0.6394" |
| 225 | 0.5067" | 0.5625" | 0.5067" | 0.5281" | 0.6957" |
| 250 | 0.5630" | 0.6250" | 0.5630" | 0.5867" | 0.7520" |
| 275 | 0.6193" | 0.6875" | 0.6193" | 0.6454" | 0.8083" |
| 300 | 0.6756" | 0.7500" | 0.6756" | 0.7041" | 0.8646" |
| 325 | 0.7319" | 0.8125" | 0.7319" | 0.7628" | 0.9209" |
| 350 | 0.7882" | 0.8750" | 0.7882" | 0.8215" | 0.9772" |
| 375 | 0.8445" | 0.9375" | 0.8445" | 0.8801" | 1.0335" |
| 400 | 0.9008" | 1.0000" | 0.9008" | 0.9388" | 1.0898" |
| 425 | 0.9571" | 1.0625" | 0.9571" | 0.9975" | 1.1461" |
| 450 | 1.0134" | 1.1250" | 1.0134" | 1.0562" | 1.2024" |
| 475 | 1.0697" | 1.1875" | 1.0697" | 1.1148" | 1.2587" |
| 500 | 1.1260" | 1.2500" | 1.1260" | 1.1735" | 1.3150" |
| 525 | 1.1823" | 1.3125" | 1.1823" | 1.2322" | 1.3713" |
| 550 | 1.2386" | 1.3750" | 1.2386" | 1.2909" | 1.4276" |
| 575 | 1.2949" | 1.4375" | 1.2949" | 1.3495" | n/a |
| 600 | 1.3512" | 1.5000" | 1.3512" | 1.4082" | n/a |
| 625 | 1.4075" | 1.5625" | n/a | 1.4669" | n/a |
| 650 | 1.4638" | 1.6250" | n/a | 1.5256" | n/a |
| 675 | 1.5201" | 1.6875" | n/a | 1.5842" | n/a |
| 700 | 1.5764" | 1.7500" | n/a | 1.6429" | n/a |
| 725 | 1.6327" | 1.8125" | n/a | 1.7016" | n/a |
| 750 | 1.6890" | 1.8750" | n/a | 1.7603" | n/a |
| 775 | 1.7453" | 1.9375" | n/a | 1.8189" | n/a |
| 800 | 1.8016" | n/a | n/a | 1.8776" | n/a |
Hardcover case laminate is limited to 75 to 550 pages. Paperbacks accept 24 to 828 pages on white paper or premium color, 24 to 776 on cream, and 72 to 600 in standard color. Books below 80 pages cannot have text on the spine under KDP rules, regardless of paper type.
The 80 page spine-text rule.
KDP only prints spine text on books with more than 79 pages, so it rejects any cover with text on the spine if the book has fewer than 80 pages. This is a hard rule, not a guideline. On books that qualify, keep spine text at least 0.0625 inches from each spine edge.
For books under 80 pages, the spine still exists in the cover file. Design it with continuous art or a solid colour. No title, no author, no subtitle. The moment any character lands on the spine, Amazon's automated cover review flags the file and the upload fails.
Hardcover vs paperback spine width.
Paperback and hardcover use the same paper-thickness multipliers, but a hardcover spine adds 4.8 mm (0.189 inches) for the case, and hardcover covers also wrap around the boards, so the total cover spread is wider than the spine itself.
Paperback (white)
0.002252" per page
300 pages = 0.6756" spine.
Allowed page range: 24 to 828. Perfect-bound, no wrap. The spine is the only edge connecting front and back cover.
Hardcover (case laminate)
0.002252" per page + 0.189"
300 pages = 0.8646" spine (white paper).
Allowed page range: 75 to 550. The boards are 5 mm wider and 6 mm taller than the trim, and the cover wraps 15 mm (0.591 inches) around them on every side.
Hardcover spine width formula
Hardcover Spine Width = (Page Count × Paper Thickness) + 0.189"
75 pages, white
0.3579"
200 pages, white
0.6394"
550 pages, white
1.4276"
If you publish the same manuscript as both formats, you need two different cover files. The paperback and hardcover spines differ because a hardcover adds 4.8 mm for the case, and the total cover dimensions differ because of the hardcover boards and wrap. Use the cover size calculator for the full cover spread.
How to apply your spine width to a cover file.
Get your total cover canvas
The spine sits between the front and back cover. Total cover width = (Trim Width × 2) + Spine Width + (Bleed × 2). Use the cover size calculator to get the full canvas in one step.
Place spine guides in your design tool
Add two vertical guides to mark the spine boundaries. In Photoshop, InDesign, or Affinity, position them at (Bleed + Trim Width) from the left edge and (Bleed + Trim Width + Spine Width) from the left edge. Anything between those guides is the spine zone. Keep spine text 0.0625 inches inside each spine edge for safety.
Or skip the manual setup entirely
KDPEasy auto-calculates spine width as part of cover generation. Enter your page count and paper type once. The AI sizes the spine, places the title and author at the safe-text margin, and exports a print-ready PDF at 300 DPI with bleed baked in.
You have the spine width. Let AI build the cover that fits it.
Feed your page count and paper type into KDPEasy. The AI sizes the spine to your exact 0.002252 spec, generates a print-ready front, back, and spine in about two minutes, and exports a KDP-compliant PDF.
- Spine width auto-calculated from page count and paper type
- Title and author placed at the safe-text margin automatically
- Print-ready PDF at 300 DPI with bleed baked in
- Paperback and hardcover formats, all KDP trim sizes
Related free tools.
KDP Cover Size Calculator
Full cover canvas with bleed and 300 DPI pixel size.
KDP Bleed & Margin Calculator
Safe bleed, gutter and outside margins for every trim.
KDP Royalty Calculator
Royalty by price, page count, and marketplace.
Word Count to Page Calculator
Estimate page count before you have a manuscript.
KDP spine width questions, answered.
What is the KDP spine width formula?
The KDP spine width formula is: Spine Width = Page Count x Paper Thickness. Paper thickness depends on paper type. White paper uses 0.002252 inches per page, cream uses 0.0025, standard color uses 0.002252 (it prints on white paper), and premium color uses 0.002347. Hardcover case laminate uses the same paper thickness and adds 4.8 mm (0.189 inches) for the case. For a 200 page white paper paperback, that is 200 x 0.002252 = 0.4504 inches.
What is 0.002252 inches per page for KDP?
0.002252 inches is the exact caliper thickness of one page of KDP white paper. It is the paper-thickness multiplier Amazon uses in its official spine width formula for white paper and standard color books. Multiply your page count by 0.002252 to get the spine width of a paperback. A hardcover adds 4.8 mm (0.189 inches) for the case.
How do I calculate KDP spine width for white paper?
Multiply your page count by 0.002252. A 100 page white paper book is 100 x 0.002252 = 0.2252 inches. A 300 page white paper book is 300 x 0.002252 = 0.6756 inches. The calculator above does this instantly and also outputs millimetres and 300 DPI pixel values.
What is the spine width for a 20 page book on white paper?
A 20 page book on white paper has a spine width of 20 x 0.002252 = 0.04504 inches, or about 1.14 mm. However, KDP does not allow text on spines under 80 pages, so design this book with art or solid colour only. Note that 20 pages is below KDP's 24 page paperback minimum, so the book itself would also be rejected at that page count.
What is the spine width for a 75 page hardcover book?
A 75 page hardcover (case laminate, white interior) has a spine width of (75 x 0.002252) + 0.189 = 0.358 inches, or about 9.09 mm: the page stack plus the 4.8 mm KDP adds for the case. 75 pages is the minimum allowed for KDP hardcover books. The hardcover cover also wraps 15 mm (0.591 inches) around the boards on every side of the full cover canvas, which is separate from the spine itself.
What is the spine width for a 200 page book?
A 200 page book on white paper has a spine width of 0.4504 inches (11.44 mm, 135 px at 300 DPI). On cream paper it is 0.5 inches. On standard color it is also 0.4504 inches. On premium color it is 0.4694 inches. As a white paper hardcover (case laminate) it is 0.6394 inches, because KDP adds 4.8 mm for the case.
Does KDP allow spine text on every book?
No. KDP only prints spine text on books with more than 79 pages, so you need at least 80 pages before you can place text on the spine. Below 80 pages, Amazon's automated cover review will reject any spine with characters on it. On books that qualify, keep spine text 0.0625 inches from each spine edge. Design any short book with continuous art on the spine and put your title and author on the front and back covers.
How do you calculate hardcover spine width on KDP?
KDP hardcover case laminate uses the same paper thickness per page as a paperback and adds 4.8 mm (0.189 inches) for the case: Spine Width = (Page Count x Paper Thickness) + 0.189 inches. A 300 page white paper hardcover is (300 x 0.002252) + 0.189 = 0.865 inches. Hardcover books on KDP are limited to 75 to 550 pages. The total cover spread also uses boards 5 mm wider and 6 mm taller than the trim, with 15 mm (0.591 inches) of wrap on every side, handled separately by the cover size calculator.
What is the spine width formula for cream paper?
Cream paper uses 0.0025 inches per page. The formula is Spine Width = Page Count x 0.0025. A 200 page cream paperback is 200 x 0.0025 = 0.5 inches. Cream is roughly 11 percent thicker than white per page, so the same manuscript produces a noticeably fatter book on cream. Always recalculate if you switch paper type after the cover is designed.
Why does KDP use 0.002252 specifically?
0.002252 is the measured caliper thickness of the 60 lb white uncoated paper Amazon uses for KDP paperback interiors. It is a precise specification from Amazon's print partner, not an approximation. Using 0.0025 or rounding to 0.0023 produces a spine width that does not match the printed book, which causes spine creep, off-centre art, or a rejected cover at upload.
How wide is the spine of a 100 page paperback?
A 100 page white paper paperback has a spine width of 100 x 0.002252 = 0.2252 inches, or about 5.72 mm. A 100 page cream paperback is 0.25 inches. Both can carry spine text under KDP rules because KDP prints spine text on books with more than 79 pages. Keep the text 0.0625 inches from each spine edge.
Can I add a safety buffer to my spine width?
No. The KDP spine width formula is exact. Adding extra width misaligns your front and back cover and causes the spine art to wrap onto the front or back. For safety, keep spine text 0.0625 inches inside each spine edge so minor printing tolerance does not crop your title. A paperback spine is the page stack alone; only hardcovers add a fixed 4.8 mm for the case.
Does premium color use a different spine width formula?
The formula is the same, but the paper is not. KDP premium color prints on a thicker white paper at 0.002347 inches per page. Standard color prints on the same white paper as black and white books, at 0.002252 inches per page. Always check which color option you selected in the KDP interior setup before using the calculator.
What is the minimum spine width for text on KDP?
KDP sets the minimum by page count, not by width: it prints spine text only on books with more than 79 pages. At 80 pages on white paper the spine is 80 x 0.002252 = 0.1802 inches (4.58 mm). Spine text must also stay 0.0625 inches (1.59 mm) from each spine edge.
You have the spine width. Now generate the cover.
AI-powered, print-ready front, back, and spine, sized to your exact 0.002252 spec.