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 79 page spine-text rule check, hardcover case laminate, and all five KDP paper types.
The official KDP spine width formula
Spine Width = (Page Count × Paper Thickness) + 0.06"
- White paper: 0.002252 inches per page
- Cream paper: 0.0025 inches per page
- Premium color: 0.002252 inches per page
- Standard color: 0.0032 inches per page
- Hardcover case laminate: 0.002347 inches per page
The official KDP formula
Spine Width = (Page Count x Paper Thickness) + 0.06" cover allowance
White paper uses 0.002252 inches per page. Cream uses 0.0025. Hardcover case laminate uses 0.002347.
Your book details
Enter page count and choose paper type.
Allowed range for this binding: 24 to 828 pages.
Most common KDP paper. Used for novels and non-fiction.
Calculation breakdown
200 x 0.002252 = 0.4504"
+ 0.06 cover allowance = 0.5104"
Your spine width
Print-ready values in three units.
Spine width (with cover allowance)
0.5104"
Use this value when laying out your full cover spread.
Inches
0.5104"
Millimetres
12.96 mm
Pixels @ 300 DPI
153 px
Spine text is allowed
At 200 pages your spine is wide enough for a title and author name. Minimum text-safe spine width is 0.0625".
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. The 0.06 inch cover allowance is the same for every book.
Formula
Spine Width = (Page Count × Paper Thickness) + 0.06"
Worked example: 100 pages, white paper, 0.002252 per page
Page count = 100
White paper thickness = 0.002252"
Pages contribution = 100 × 0.002252 = 0.2252"
Cover allowance = 0.0600"
Total spine width = 0.2252 + 0.0600 = 0.2852"
That is 7.24 mm, or 86 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 + 0.06"?
The 0.06 inch cover allowance accounts for the printed cover stock itself, which has its own thickness independent of the interior pages. Skipping this allowance is the most common reason a freshly designed spine fails KDP review.
The arithmetic is identical for every paper type. Swap the multiplier: 0.002252 for white paper or premium color, 0.0025 for cream, 0.0032 for standard color, 0.002347 for hardcover case laminate.
KDP paper-thickness multipliers.
All five paper-thickness constants Amazon publishes for KDP. 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 |
| Premium Color | 0.002252" | Same paper as white |
| Standard Color | 0.0032" | 80 lb, thickest paperback |
| Hardcover Case Laminate | 0.002347" | Different binding |
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 0.06 inch cover allowance.
20 pages
White
20 × 0.002252 + 0.06
0.1050"
Below KDP minimum (24 pages)
50 pages
White
50 × 0.002252 + 0.06
0.1726"
No spine text (under 79 pages)
75 pages
White
75 × 0.002252 + 0.06
0.2289"
No spine text (under 79 pages)
100 pages
White
100 × 0.002252 + 0.06
0.2852"
Spine text allowed
150 pages
White
150 × 0.002252 + 0.06
0.3978"
Spine text allowed
200 pages
White
200 × 0.002252 + 0.06
0.5104"
Spine text allowed
300 pages
White
300 × 0.002252 + 0.06
0.7356"
Spine text allowed
400 pages
White
400 × 0.002252 + 0.06
0.9608"
Spine text allowed
200 pages
Cream
200 × 0.0025 + 0.06
0.5600"
Spine text allowed
300 pages
Cream
300 × 0.0025 + 0.06
0.8100"
Spine text allowed
75 pages
Hardcover
75 × 0.002347 + 0.06
0.2360"
No spine text (under 79 pages)
300 pages
Hardcover
300 × 0.002347 + 0.06
0.7641"
Spine text allowed
KDP spine width chart, every 25 pages.
Every spine width KDP accepts, in increments of 25 pages, across all five paper types. Values are total spine width in inches, including the 0.06 inch cover allowance. Each cell is also valid as a print-ready measurement at 300 DPI.
| Pages | White (0.002252) | Cream (0.0025) | Premium Color (0.002252) | Standard Color (0.0032) | Hardcover (0.002347) |
|---|---|---|---|---|---|
| 24No spine text | 0.1140" | 0.1200" | 0.1140" | 0.1368" | n/a |
| 50No spine text | 0.1726" | 0.1850" | 0.1726" | 0.2200" | n/a |
| 75No spine text | 0.2289" | 0.2475" | 0.2289" | 0.3000" | 0.2360" |
| 100 | 0.2852" | 0.3100" | 0.2852" | 0.3800" | 0.2947" |
| 125 | 0.3415" | 0.3725" | 0.3415" | 0.4600" | 0.3534" |
| 150 | 0.3978" | 0.4350" | 0.3978" | 0.5400" | 0.4121" |
| 175 | 0.4541" | 0.4975" | 0.4541" | 0.6200" | 0.4707" |
| 200 | 0.5104" | 0.5600" | 0.5104" | 0.7000" | 0.5294" |
| 225 | 0.5667" | 0.6225" | 0.5667" | 0.7800" | 0.5881" |
| 250 | 0.6230" | 0.6850" | 0.6230" | 0.8600" | 0.6467" |
| 275 | 0.6793" | 0.7475" | 0.6793" | 0.9400" | 0.7054" |
| 300 | 0.7356" | 0.8100" | 0.7356" | 1.0200" | 0.7641" |
| 325 | 0.7919" | 0.8725" | 0.7919" | 1.1000" | 0.8228" |
| 350 | 0.8482" | 0.9350" | 0.8482" | 1.1800" | 0.8815" |
| 375 | 0.9045" | 0.9975" | 0.9045" | 1.2600" | 0.9401" |
| 400 | 0.9608" | 1.0600" | 0.9608" | 1.3400" | 0.9988" |
| 425 | 1.0171" | 1.1225" | 1.0171" | 1.4200" | 1.0575" |
| 450 | 1.0734" | 1.1850" | 1.0734" | 1.5000" | 1.1162" |
| 475 | 1.1297" | 1.2475" | 1.1297" | 1.5800" | 1.1748" |
| 500 | 1.1860" | 1.3100" | 1.1860" | 1.6600" | 1.2335" |
| 525 | 1.2423" | 1.3725" | 1.2423" | 1.7400" | 1.2922" |
| 550 | 1.2986" | 1.4350" | 1.2986" | 1.8200" | 1.3509" |
| 575 | 1.3549" | 1.4975" | 1.3549" | 1.9000" | n/a |
| 600 | 1.4112" | 1.5600" | 1.4112" | 1.9800" | n/a |
| 625 | 1.4675" | 1.6225" | 1.4675" | 2.0600" | n/a |
| 650 | 1.5238" | 1.6850" | 1.5238" | 2.1400" | n/a |
| 675 | 1.5801" | 1.7475" | 1.5801" | 2.2200" | n/a |
| 700 | 1.6364" | 1.8100" | 1.6364" | 2.3000" | n/a |
| 725 | 1.6927" | 1.8725" | 1.6927" | 2.3800" | n/a |
| 750 | 1.7490" | 1.9350" | 1.7490" | 2.4600" | n/a |
| 775 | 1.8053" | 1.9975" | 1.8053" | 2.5400" | n/a |
| 800 | 1.8616" | 2.0600" | 1.8616" | 2.6200" | n/a |
Hardcover case laminate is limited to 75 to 550 pages. All other paper types accept 24 to 828 pages. Books below 79 pages cannot have text on the spine under KDP rules, regardless of paper type.
The 79 page spine-text rule.
KDP rejects any cover with text on the spine if the book has fewer than 79 pages. This is a hard rule, not a guideline. The minimum spine width Amazon publishes that can carry text is 0.0625 inches, but the 79 page rule is the binding constraint for most books because it triggers first.
For books under 79 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 different paper-thickness multipliers. The 0.06 inch cover allowance is identical, but hardcover books also wrap around the boards, so the total cover spread is wider than the spine itself.
Paperback (white)
0.002252" per page
300 pages = 0.7356" 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)
0.002347" per page
300 pages = 0.7641" spine.
Allowed page range: 75 to 550. Add 0.625 inches of wrap on every side of the total cover canvas for the board overhang.
Hardcover spine width formula
Hardcover Spine Width = (Page Count × 0.002347) + 0.06"
75 pages
0.2360"
200 pages
0.5294"
550 pages
1.3509"
If you publish the same manuscript as both formats, you need two different cover files. The paperback and hardcover spines differ because the paper multiplier differs, and the total cover dimensions differ because of the hardcover 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) + 0.06 inches for the cover allowance. Paper thickness depends on paper type. White paper uses 0.002252 inches per page, cream uses 0.0025, premium color uses 0.002252, standard color uses 0.0032, and hardcover case laminate uses 0.002347. For a 200 page white paper paperback, that is (200 x 0.002252) + 0.06 = 0.5104 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 paperbacks and premium color paperbacks. Multiply your page count by 0.002252 to get the pages contribution, then add the 0.06 inch cover allowance to get the total spine width.
How do I calculate KDP spine width for white paper?
Multiply your page count by 0.002252 then add 0.06 inches for the cover allowance. A 100 page white paper book is (100 x 0.002252) + 0.06 = 0.2852 inches. A 300 page white paper book is (300 x 0.002252) + 0.06 = 0.7356 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) + 0.06 = 0.10504 inches, or about 2.67 mm. However, KDP does not allow text on spines under 79 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 0.002347) + 0.06 = 0.236 inches, or about 6.0 mm. 75 pages is the minimum allowed for KDP hardcover books. The hardcover book also adds 0.625 inches of wrap 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 0.5104 inches (12.96 mm, 153 px at 300 DPI). On cream paper it is 0.56 inches. On premium color it is also 0.5104 inches. On standard color it is 0.7 inches. On hardcover case laminate it is 0.5294 inches. All values include the 0.06 inch cover allowance.
Does KDP allow spine text on every book?
No. KDP requires a minimum of 79 pages before you can place text on the spine. Below 79 pages, Amazon's automated cover review will reject any spine with characters on it. The text-safe minimum spine width Amazon publishes is 0.0625 inches, but the 79 page rule is the hard gate. 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 0.002347 inches per page. The formula is unchanged: Spine Width = (Page Count x 0.002347) + 0.06 inches. A 300 page hardcover is (300 x 0.002347) + 0.06 = 0.7641 inches. Hardcover books on KDP are limited to 75 to 550 pages. The total cover spread also adds 0.625 inches of board 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) + 0.06 inches. A 200 page cream paperback is (200 x 0.0025) + 0.06 = 0.56 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) + 0.06 = 0.2852 inches, or about 7.24 mm. A 100 page cream paperback is 0.31 inches. Both are wide enough for spine text under KDP rules because 100 pages exceeds the 79 page minimum and both spines exceed the 0.0625 inch text-safe threshold.
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. The formula already includes the 0.06 inch cover allowance that accounts for the cover material thickness.
Does premium color use a different spine width formula?
No. KDP premium color uses the same 0.002252 inches per page as white paper. The premium color option is white paper with full colour printing on the same 60 lb stock. Standard color, however, prints on a thicker 80 lb paper at 0.0032 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's published minimum spine width that can carry text is 0.0625 inches (1.59 mm). The book must also have at least 79 pages, which on white paper produces a spine of (79 x 0.002252) + 0.06 = 0.2379 inches. The 79 page page-count rule is the binding constraint for most books, not the 0.0625 inch width.
You have the spine width. Now generate the cover.
AI-powered, print-ready front, back, and spine, sized to your exact 0.002252 spec.