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Guide

KDP spine width formula, with a table for every page count

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We build free, sourced tools for self-publishing authors and check every spec against the official help pages.

Last updated 4 min read

Short answer

KDP spine width equals page count times the paper's thickness per page. Use 0.002252 in per page for white paper, 0.0025 in for cream, 0.00235 in for groundwood, 0.002252 in for standard color and 0.002347 in for premium color. A 300-page book on white paper has a 0.676 in spine.

What is the KDP spine width formula?

A KDP paperback spine is as wide as the stack of pages inside it. KDP gives a thickness per page for each paper, so the spine width is one multiplication:

Spine width = page count x paper thickness per page

The result is in inches. Multiply by 25.4 for millimeters.

How thick is each KDP paper per page?

KDP lists five ink and paper options. White paper and standard color share the same thickness; cream is the thickest. The page range is the widest KDP allows for that paper across all trim sizes. Larger trims allow fewer pages.

KDP paperback spine thickness per page
PaperInches per pagemm per pageSpine per 100 pagesPage range
White paper, black ink0.0022520.05720.225 in24 to 828
Cream paper, black ink0.00250.06350.250 in24 to 776
Groundwood paper, black ink0.002350.05970.235 in24 to 812
Standard color0.0022520.05720.225 in72 to 600
Premium color0.0023470.05960.235 in24 to 828

How wide is the spine for my page count?

Find your page count in the left column. Widths are in inches, rounded to three decimals. n/a means KDP does not print that page count on that paper at any trim size. For a page count between rows, use the formula or the cover calculator, which also checks the limit for your exact trim.

KDP spine width in inches, by page count and paper
PagesWhiteCreamGroundwoodStandard colorPremium color
240.0540.0600.056n/a0.056
300.0680.0750.071n/a0.070
400.0900.1000.094n/a0.094
500.1130.1250.118n/a0.117
600.1350.1500.141n/a0.141
700.1580.1750.165n/a0.164
800.1800.2000.1880.1800.188
900.2030.2250.2120.2030.211
1000.2250.2500.2350.2250.235
1100.2480.2750.2590.2480.258
1200.2700.3000.2820.2700.282
1300.2930.3250.3050.2930.305
1400.3150.3500.3290.3150.329
1500.3380.3750.3530.3380.352
1600.3600.4000.3760.3600.376
1700.3830.4250.4000.3830.399
1800.4050.4500.4230.4050.422
1900.4280.4750.4470.4280.446
2000.4500.5000.4700.4500.469
2100.4730.5250.4930.4730.493
2200.4950.5500.5170.4950.516
2300.5180.5750.5400.5180.540
2400.5400.6000.5640.5400.563
2500.5630.6250.5880.5630.587
2600.5860.6500.6110.5860.610
2700.6080.6750.6350.6080.634
2800.6310.7000.6580.6310.657
2900.6530.7250.6810.6530.681
3000.6760.7500.7050.6760.704
3100.6980.7750.7290.6980.728
3200.7210.8000.7520.7210.751
3300.7430.8250.7760.7430.775
3400.7660.8500.7990.7660.798
3500.7880.8750.8230.7880.821
3600.8110.9000.8460.8110.845
3700.8330.9250.8700.8330.868
3800.8560.9500.8930.8560.892
3900.8780.9750.9160.8780.915
4000.9011.0000.9400.9010.939
4100.9231.0250.9640.9230.962
4200.9461.0500.9870.9460.986
4300.9681.0751.0100.9681.009
4400.9911.1001.0340.9911.033
4501.0131.1251.0581.0131.056
4601.0361.1501.0811.0361.080
4701.0581.1751.1051.0581.103
4801.0811.2001.1281.0811.127
4901.1031.2251.1511.1031.150
5001.1261.2501.1751.1261.173
5101.1491.2751.1991.1491.197
5201.1711.3001.2221.1711.220
5301.1941.3251.2461.1941.244
5401.2161.3501.2691.2161.267
5501.2391.3751.2921.2391.291
5601.2611.4001.3161.2611.314
5701.2841.4251.3401.2841.338
5801.3061.4501.3631.3061.361
5901.3291.4751.3871.3291.385
6001.3511.5001.4101.3511.408
6101.3741.5251.433n/a1.432
6201.3961.5501.457n/a1.455
6301.4191.5751.481n/a1.479
6401.4411.6001.504n/a1.502
6501.4641.6251.528n/a1.526
6601.4861.6501.551n/a1.549
6701.5091.6751.575n/a1.572
6801.5311.7001.598n/a1.596
6901.5541.7251.622n/a1.619
7001.5761.7501.645n/a1.643
7101.5991.7751.669n/a1.666
7201.6211.8001.692n/a1.690
7301.6441.8251.716n/a1.713
7401.6661.8501.739n/a1.737
7501.6891.8751.763n/a1.760
7601.7121.9001.786n/a1.784
7701.7341.9251.810n/a1.807
7801.757n/a1.833n/a1.831
7901.779n/a1.857n/a1.854
8001.802n/a1.880n/a1.878
8101.824n/a1.903n/a1.901
8201.847n/an/an/a1.925
8281.865n/an/an/a1.943

How do I get the full cover size from the spine width?

A paperback cover is one flat sheet: back cover, spine and front cover side by side, with bleed around the outside. KDP adds 0.125 in of bleed to the top, bottom and outside edges.

Width = bleed + trim width + spine + trim width + bleed
Height = bleed + trim height + bleed

Worked example

A 6 x 9 in paperback with 300 pages on white paper:

  1. Spine: 300 x 0.002252 = 0.6756 in (17.16 mm).
  2. Width: 0.125 + 6 + 0.6756 + 6 + 0.125 = 12.9256 in.
  3. Height: 0.125 + 9 + 0.125 = 9.250 in.

The full cover is 12.9256 x 9.250 in (328.3 x 234.9 mm). The KDP cover calculator does this for any trim and draws a template with the fold lines, safe areas and barcode box in place.

When can I put text on the spine?

Thin books cannot carry spine text, because a small shift at the fold would push the letters onto the front or back. KDP says "at least 79 pages" in one place and "more than 79 pages" in another, and Cover Creator needs 80. We use 80 so the warning is never too late.

  • Below 80 pages: leave the spine plain, or use a solid color that runs across it.
  • From 80 pages: keep text at least 0.0625 in from each spine edge.
  • At 80 pages on white paper the spine is only 0.180 in wide, so short titles in a condensed face work best.

Why does my printed spine not match exactly?

Binding is a physical process. KDP allows a variance of 0.0625 in on either side of each fold line, so the spine edge can land a little to the left or right. Design for it:

  • Do not put a hard edge, border or color change right on the fold.
  • Run spine and cover backgrounds past the fold so a shift shows the same color.
  • Recalculate the spine whenever the page count changes, even by a few pages.

Do IngramSpark and Lulu use the same formula?

No, so a cover built for KDP will not always fit another printer.

  • Lulu paperbacks use (pages / 444) + 0.06 in. At 300 pages that is 0.736 in, against 0.676 in on KDP white paper.
  • IngramSpark publishes no per page rate. Its spine calculator gives the width for your paper and page count. Paste that number into our cover calculator to get the template.

Questions authors ask

How wide is the spine of a 200-page book on KDP?

0.450 in (11.4 mm) on white paper and 0.500 in (12.7 mm) on cream paper. Multiply 200 by the paper's per page thickness: 0.002252 in for white, 0.0025 in for cream.

Why is a cream paper spine wider than white?

Cream paper is thicker: 0.0025 in per page against 0.002252 in for white. At 300 pages that adds 0.074 in to the spine, so a cover made for white paper will not fit a cream paper interior. Choose the paper before you design the cover.

Do blank pages count toward the spine width?

Yes. Use the final page count of your interior file, blank pages included. Every page is a printed sheet side, so it adds thickness. If your page count changes, recalculate the spine and update the cover.

How many pages do I need for text on the spine?

We use 80 pages for KDP. KDP says "at least 79 pages" in one place and "more than 79 pages" in another, and Cover Creator needs 80. We use 80 so the warning is never too late. Keep spine text at least 0.0625 in from each spine edge.

How much bleed does a KDP paperback cover need?

0.125 in, added to the top, bottom and outside edges of the full cover. That is why the full cover is 0.25 in wider and taller than the trim, spine included.

Does IngramSpark or Lulu use the same spine formula?

No. Lulu paperbacks use (pages / 444) + 0.06 in, so 300 pages give 0.736 in. IngramSpark publishes no per page rate; its spine calculator returns the width for your exact book, and our cover calculator takes that number.

Sources

Every number in this guide comes from our spec data, last verified against the official help pages below. Retailers change their terms, so check the source before you rely on a figure.

KDP

Lulu and IngramSpark