Leaf & Spine

5.5 x 8.5 in Digest · 370 pages

370-page 5.5 x 8.5 in book: spine width & cover size

A 370-page 5.5 x 8.5 in paperback has a spine of 0.8332 in (21.16 mm) on white paper or 0.925 in on cream. Full cover with bleed: 12.083 x 8.75 in.

0.833 inSpine, white paper21.16 mm
0.925 inSpine, cream paper23.5 mm
12.08 x 8.75Full cover, inchesincl. bleed
435 gEstimated weight15.3 oz

Cover template (white paper)

Barcode areaBACK COVER5.5 x 8.5 inFRONT COVER5.5 x 8.5 inSPINE 0.833 inFull cover 12.083 x 8.75 in incl. 0.125 in bleed
Red: bleed (trimmed off) · dashed: 0.25 in safe zone · shaded: spine. Download a full-size template from the calculator.

Spine and cover by paper type

PaperSpineSpine (mm)Full cover (in)Full cover (mm)At 300 ppi
White paper, black ink0.8332 in21.16 mm12.083 x 8.75 in306.9 x 222.3 mm3,625 x 2,625 px
Cream paper, black ink0.925 in23.5 mm12.175 x 8.75 in309.2 x 222.3 mm3,652 x 2,625 px
Standard color (white)0.8332 in21.16 mm12.083 x 8.75 in306.9 x 222.3 mm3,625 x 2,625 px
Premium color (white)0.8684 in22.06 mm12.118 x 8.75 in307.8 x 222.3 mm3,636 x 2,625 px

Per-page factors are those published by KDP; IngramSpark and offset printers use their own paper calipers.

Other printers: spine by paper PPI

Paper PPITypical stockSpineSpine (mm)
350 PPIBulky / heavy stock (~70 lb text)1.0571 in26.85 mm
400 PPICream book paper (~55 lb)0.925 in23.5 mm
444 PPIWhite book paper (~50 lb)0.8333 in21.17 mm
500 PPILightweight text (~45 lb)0.74 in18.8 mm
600 PPIThin text (~40 lb)0.6167 in15.66 mm

If your printer quotes pages per inch (PPI), spine = pages ÷ PPI. Ask for the exact PPI of your chosen stock.

Designing this cover

  • Build the cover canvas at 12.083 x 8.75 in — or 3,625 x 2,625 px at 300 ppi.
  • The back cover runs from the left edge to 5.625 in; the spine from 5.625 to 6.458 in; the front cover after that.
  • Spine text is allowed — centre it and keep 0.0625 in clear on each side.
  • Keep titles and faces at least 0.25 in inside the trim; KDP places the barcode in a 2 x 1.2 in area at the lower right of the back cover.
  • Export as a flattened PDF (PDF/X-1a is safest) with fonts embedded.

Nearby page counts

PagesSpine (white)Spine (cream)Full cover (white)
310 pages0.6981 in0.775 in11.948 x 8.75 in
320 pages0.7206 in0.8 in11.971 x 8.75 in
330 pages0.7432 in0.825 in11.993 x 8.75 in
340 pages0.7657 in0.85 in12.016 x 8.75 in
350 pages0.7882 in0.875 in12.038 x 8.75 in
360 pages0.8107 in0.9 in12.061 x 8.75 in
380 pages0.8558 in0.95 in12.106 x 8.75 in
390 pages0.8783 in0.975 in12.128 x 8.75 in
400 pages0.9008 in1 in12.151 x 8.75 in
410 pages0.9233 in1.025 in12.173 x 8.75 in
420 pages0.9458 in1.05 in12.196 x 8.75 in
430 pages0.9684 in1.075 in12.218 x 8.75 in

370 pages in other trim sizes

TrimSpine (white)Full cover (white)
5 x 8 in0.8332 in11.083 x 8.25 in
5.06 x 7.81 in0.8332 in11.203 x 8.06 in
5.25 x 8 in0.8332 in11.583 x 8.25 in
6 x 9 in0.8332 in13.083 x 9.25 in
6.14 x 9.21 in0.8332 in13.363 x 9.46 in
6.69 x 9.61 in0.8332 in14.463 x 9.86 in
7 x 10 in0.8332 in15.083 x 10.25 in
7.5 x 9.25 in0.8332 in16.083 x 9.5 in
8 x 10 in0.8332 in17.083 x 10.25 in
8.5 x 8.5 in0.8332 in18.083 x 8.75 in
8.5 x 11 in0.8332 in18.083 x 11.25 in

Spine width depends only on page count and paper; the cover width changes with the trim.

Frequently asked questions

How wide is the spine of a 370-page 5.5 x 8.5 in book?
On white paper it is 0.8332 in (21.16 mm); on cream paper 0.925 in (23.5 mm), using KDP's per-page factors.
What size should the full cover be?
For white paper: 12.083 x 8.75 in (306.9 x 222.3 mm) including 0.125 in bleed on every side. For cream paper: 12.175 x 8.75 in.
Can I put text on the spine?
Yes. KDP allows spine text only for books with more than 79 pages; keep it at least 0.0625 in (1.6 mm) from each spine edge.
How heavy is a 370-page 5.5 x 8.5 in paperback?
About 435 g (15.3 oz) on white paper with a standard cover — useful for estimating postage.