How to calculate the spine width of your paperback

Design book cover

When designing the perfect book cover, you’ll need to factor in the width of the spine. 

There are numerous book spine calculators available online to help take the guesswork out of it — but what if you want to just do it yourself? Good news, you’re about to learn how!

What’s needed to calculate spine width?

To calculate spine width, you need to know the final page count and paper weight(s). The more pages in your book, the thicker the spine. If those pages are on a heavier paper, the spine width increases. Conversely, if the paper is lighter weight, the spine width decreases.

Calculating your book’s page count

If this is your first book design project, you may be tempted to base your count on the page count shown in MS Word. But for printing and to calculate spine width, you need to know the page count of your book in its final printed form. And this will depend on the dimensions you choose for your printed book.
For example, if you wrote your book in Word using 8.5″x11″ as the document size, and then choose to print a book that is 6″x9″ — you’ll see the page count significantly increase when factoring in the new size and margins. 
You’ll likely want to include a title page, maybe a dedication page or acknowledgements and these will also add to your count.

Calculating your book’s PPI

Once you’ve taken all of the above into consideration, it’s time to choose what paper your book will be printed on, so that you can work out the pages per inch.

Here are some real numbers to work with, based on our most common paper types:

Royal Palm Press - Paper StockPages per inch (PPI)
50# White Inside Pages535 ppi
60# White Inside Pages440 ppi
70# White Inside Pages376 ppi
80# White Inside Pages324 ppi
Cover Stock
10pt White CoverAdd .02"
12pt White CoverAdd .03"

Putting the formula to work

Now let’s put it all together to calculate the spine width of your perfect bound soft cover book:
[Page Count] divided by [PPI] plus Cover Stock
Example — Your soft cover book has 186 inside pages printed on 60# white with a 10pt cover:
(186 pages / 440ppi) + .02″ cover = .443″ spine

Need help calculating your spine? Get in touch with us!