Getting a manuscript into print
Writing the book is the hard part. Turning it into an object is a set of measurements, and they are less mysterious than the printing trade makes them sound.
A self-publishing author meets a run of questions nobody warned them about. How thick will the book be? How much bleed does the cover need? Why does one printer talk about grammage and volume while another talks about pages per inch, and why do they disagree about the same book? What is a signature, and why has a 250-page manuscript become 256 pages?
Most of these have exact answers, published by printers and paper mills, but they are scattered across trade specification sheets written for people who already know the vocabulary. This section works through them one at a time, in plain English, with the arithmetic shown rather than hidden inside a black box.
The emphasis is British. Most self-publishing advice online is written for the American market and quotes American conventions, which is unhelpful when your printer is in Cornwall and quotes you a paper in millimetres and volume basis. Where a British and an American practice differ, this section explains both and says which applies to you.
Start here
If you are preparing a cover for print, this is the number everything else depends on.
Book production 1 tool
Physical dimensions, paper and cover geometry for a printed book.
Guides
Long-form explanations of the parts of book production that do not reduce to a single calculation.
Useful tools elsewhere on the site
Several calculators that authors need already live in other sections, because they are useful to other people too.
The basics, in plain English
Four pieces of vocabulary account for most of the confusion in book production. They are worth ten minutes.
Grammage is weight, not thickness
Paper described as 80gsm weighs eighty grams per square metre. That says nothing directly about how thick it is. Two 80gsm papers can differ in thickness by half again, because thickness depends on how much air the fibres hold as well as how much fibre there is.
Volume basis is the thickness part
British and European merchants quote a second number alongside the weight: a volume basis, written as something like 17.5 vol. Multiply grammage by volume, divide by ten, and you have the thickness of one sheet in microns. An 80gsm paper at 17.5 vol is 140 microns; the same weight at 12.5 vol is 100 microns. That is why a printer will ask you which you want rather than simply asking for a weight.
Trim size is the finished page, not the file
The trim size is the size of a page in the book you hold. Artwork that runs to the edge has to be drawn larger than that, because the pages are printed oversized and cut down, and the cut has a tolerance. The extra margin is called bleed and is usually 3 mm, or an eighth of an inch.
A page is not a sheet
Every sheet of paper in a book carries a page on each side, so a 320-page book contains 160 sheets. This sounds obvious and is still the most common mistake in spine calculations, where entering sheets instead of pages produces an answer exactly twice as thick as it should be. It also explains why a finished book always has an even page count.
Common questions
Do I need to understand paper to publish a book?
Not to publish one, but you do to control how it turns out. Paper decides how thick the book is, how heavy it is to post, whether the spine text fits, and whether a slim novel looks slight or substantial on a shelf. Those are the decisions authors most often leave to a default and most often regret.
Why do British and American printers describe paper differently?
They measure the same property from different directions. British and European printers quote grammage in grams per square metre together with a volume basis describing bulk. American print-on-demand companies quote pages per inch, which is that calculation already done for one specific paper. Neither is more correct, but the figures are not interchangeable and mixing them produces a cover that does not fit.
Is print-on-demand the same as printing a run of books?
No, and the difference affects the specification. Print-on-demand prints single copies digitally from a fixed menu of papers and trim sizes. A short litho run is set up on a press, works in signatures of usually sixteen pages, and offers a far wider choice of paper and binding. A calculation valid for one is often not valid for the other.
Is anything I enter into these calculators stored?
No. Page counts, measurements and paper specifications are processed in your browser and never transmitted or retained.
Related subjects
Publishing a book touches on several other kinds of calculation.