Let’s begin by looking at the width and height of common documents. PDF documents are easy. At least in the US, the most common paper stock is 8 ½ inches wide by 11 inches high. When our students print a PDF version of our course book, they will be printing it on normal paper that is 8 ½ inches by 11 inches (unless they are in Europe which uses a slightly different size of paper). The trouble is that we do not want our print book to be this big because it would not fit on common book store book shelves.
The ideal size for a college text book is 8 x 10. This is basically because it is the biggest size that will fit on the book store shelves. What we want is for the same content to appear on the page regardless of whether the content is in an 8 ½ by 11 PDF Document or an 8 x 10 Print Book. The content on page 245 of the PDF book should be the same as the content on page 245 of the 8 x 10 book.
Assuming that we use minimum margins for our 8 x 10 print book of one half inch on top and bottom and one inch on each side, we will have a Print Book Paragraph Width of 6 inches and a Print Book Content area of 6 inches wide by 9 inches high. This book content area of 6 x 9 remains even after subtracting one half inch for the interior gutter – or the portion of each page glued to the binding.
Subtracting ½ inch simply leaves a margin on the inside of the page that is one half inch – the same as the margin for the top and bottom of the page. The gutter on a print book is the glue applied to the inside of each page – in other words the right side of left pages and the left side of right pages. To create the same content area in our 8 ½ inch wide by 11 inch high PDF document (and source document), our source document must have top and bottom margins of 1 inch and left and right margins of 1.25 inches.
Margins and Gutter Allowance For Perfect Binding
One of many factors that affects how we should set the margins for our default template and book template is the type of binding we will use when we publish our print book. We recommend a binding called Perfect Binding. Perfect Binding is one of the most common and least expensive ways to bind paper in a Soft Cover book. It is basically gluing the interior 1/4 inch of the pages together. However, Perfect Binding results in the first interior half inch not being readable in the printed book. This non-visible space is commonly called the gutter.
Since we should have at least one half inch margins all around the content, this means we should have interior margins of at least 1 inch - which includes 0.25 inches for the gutter and 0.25 inches for the space outside the gutter that is at an angle and thus not readable.
The next decision is whether the exterior margin should match the interior margin. If the exterior margin is 0.25 inches less than the interior margin, in other words set for 0.75 inches, the page will appear to be centered. But the problem with using this method in modern Print On Demand (POD) books is that often either the writer, the word processing program or the printer will get confused and inadvertently reverse the interior and exterior margins - resulting in pages which are very off center. This can happen from one chapter to the next simply by failing to omit the blank page needed at the end of some chapters in order to start the next chapter on an odd page. There are settings to prevent mixing up even and odd pages - or right and left pages. But these settings are often not correctly set by the author or correctly interpreted by the POD printer.
There is also a problem when using the same source document for an 8 1/2 by 11 PDF downloadable file as these pages should have equal margins so that the content is centered whether they are printed out or read online.
We therefore recommend that you do not use Left versus Right pages and instead use equal left and right margins on all pages. In short, we recommend that margins on both the right and left sides of each page be at least 1 inch and preferably 1.25 inches.
In a typical 8 x 10 book, the content width will be 8 inches minus 2 inches equals 6 inches. To have the same content width in our 8 1/2 by 11 PDF file, we will set the margins for 1.25 inches. Having the content in your documents be only 6 inches wide means that your document will take slightly more pages for the same number of words as there will be fewer words on each line. However, your readers and students will benefit because it is much easier and faster for the eye to read a 6 inch wide column of text than a 6 ½ inch column of text.