Comparing proofs from two printers
Two boxes arrive in the same week. Same interior PDF, same page count, same cover design. One book is a shade warmer than the other, visibly thicker, and opens flatter. Nothing has gone wrong.
Two printers are two machines, two paper suppliers and two binding lines. Your file is the only thing about the two jobs that is identical. The useful skill is telling their differences from yours, because one set is normal and the other set is a fault you have to go and fix.
The same page count is not the same thickness
Bulk — how thick one sheet is — is set by the paper, and every printer buys its own. The published arithmetic is not close:
- KDP white is 0.002252 in per page, cream 0.0025 in.
- Lulu computes bulk as pages ÷ 444, plus 0.06 in for glue.
- IngramSpark is not a formula but a curve off its own templates. White runs about 0.00209 in per page between 100 and 338 pages, and about 0.00192 between 338 and 700.
- B&N Press works from a measured table rather than a rate.
Run a 300-page book through those. KDP white gives 0.676 in. Lulu gives 0.736 in. IngramSpark, on the white curve, gives about 0.627 in. That is a spread of roughly 0.11 in — close to 3 mm — from one manuscript.
Those two books are physically different objects, and each one needed its own cover file with its own spine width. Sending a single exported wrap to both is a fault in your file, not in either press.
Paper shade and bulk go together
One printer's white is another's faintly warm, and the cream stocks vary more than the whites do. Lay the two books open at the same page under the same light and the difference is obvious; look at either one alone and you would not have noticed.
Neither is wrong. Shade is a stock decision, and it changes how your interior reads — warmer paper lowers contrast slightly and is easier on the eye over a long session, colder paper makes photographs and fine rules look crisper.
Cover finish and ink density
Gloss and matte are different products, and even two matte laminates from different suppliers scatter light differently. A dark cover on gloss looks deeper and more saturated; the same file on matte looks quieter and shows fingerprints less.
Ink density differs too. One press lays a heavier black than the other, so a reversed-out title can look crisp on one copy and slightly filled-in on the other. That is a press calibration, not something in your artwork.
Trim accuracy and binding tightness
Cutting has a tolerance, and the two books will not be cut identically. A millimeter of variation between them is ordinary.
Binding tightness matters more, because it is the one difference that changes how the book behaves. A tightly bound book pulls more paper into the curve, so the inner edge of the text block sits deeper in the gutter and the book resists lying flat. A looser binding opens flatter and gives you back some of that inside margin. Check both at the thickest part, in the middle.
In the tools. The Cover Maker computes the spine from the real page count, the paper color and the printer you pick, and draws up to eleven wrap files from one design — so a second printer is a re-export rather than a redraw. Start your book → · about the tools
How to compare them properly
Do it once, deliberately, rather than picking each book up over a week.
- Daylight, side by side, same page open in both. Not a kitchen lamp, which has a color cast of its own and will make one cover look warmer purely as an artifact of the bulb.
- Hold both covers at arm's length. That is browsing distance. Brightness differences shrink at that range; legibility differences do not.
- Open each flat at the same three places — near the front, the middle, the end — and watch the gutter.
- Flex the cover at a corner and run a thumb along the spine edge. You are looking for laminate that lifts or cracks, which is what handling in a shop will do to it.
- Weigh them in one hand each. Thickness and paper weight together are most of what a reader calls "quality."
Choose on what your reader will notice
Pick on the things that survive contact with a person: how the book opens, how the paper feels and reads, whether the cover still looks intact after a week in a bag.
Do not pick on which cover looks brighter under the light in your kitchen. That comparison changes with the bulb, and it is the least stable thing in front of you.
If the interior carries photographs, weight the paper above the cover finish. If it is a novel that will be handled a lot, weight the binding.
What is not a legitimate difference
The rule is simple: a fault that appears in both copies is yours.
If the title sits too close to the trim on both, that is your safe area, not their cutting — the safe area is about 0.25 in inside the trim, and both presses cut to tolerance around a line you drew too near the edge. If a page is soft and muddy in both, the image is below 300 DPI at its printed size. If a chapter opens on the wrong side in both, it is in your file.
Two printers producing the same defect is as close to a controlled experiment as you will get. Stop looking at the presses and go back to the PDF.
Practical notes
Order both at the same time. Paper batches and press calibration drift over months, so proofs ordered eight weeks apart are not comparable, and you will draw a conclusion about a printer from a difference that is really a difference in time.
Write the date and the printer on each copy — inside the back cover, in pen. In six months you will have two nearly identical books and no idea which was which, and that is how a corrected file gets sent to the wrong press.
Keep both. When you switch printer later, the copy you did not choose is your reference for what the change will actually look like.
Make your book
The tools are free to use: name your book, bring your manuscript or your artwork, and work as long as you like. You only pay when you want the files without the preview watermark.
Next: Timing your proofs around a launch date · More: Measuring your proof with a ruler · Moving a book to a different printer · White or cream paper? · How to calculate spine width