The following extract is taken from my how-to books and explains about two key printing terms: ‘trim size’ and ‘bleed’.
The term ‘trim size’ refers to the finished size of your book – i.e. after the pages have been glued inside the cover and trimmed off neatly.
There are many trim sizes available, but the most popular sizes for non-fiction are shown in Table 1 below:
As even the largest of those trim sizes is slightly smaller than a normal A4 page, the trim size you choose will inevitably change the total page count of your book.
Note: the size of a default Word document is A4, and A4 is 8.27” x 11.69” in size.
This change in page size will have consequences in terms of layout. For example, you may find large gaps on pages where the graphics no longer fit. As a result, some re-formatting will be required. Furthermore, as the spine of the cover depends upon the number of pages in the book, trim size will indirectly affect the width of the spine as well.
You can see a complete table of trim sizes available in KDP – in both inches and cm – at the web address below:
Although selecting the right trim size is the first critical step in printing your book, ‘bleed’ can be the second.
To illustrate the concept of ‘bleed’, consider the two pages below:
Note: the dotted green line represents the trim line.
The image on the left extends past the trim line into the ‘bleed’. When the page is trimmed, the image will have a crisp, clean edge with no white showing. By contrast, the image on the right does not extend into the ‘bleed’ and will have a thin white edge after it is trimmed:
Although most novels do not contain photographs, some do include maps and illustrations, and for them, bleed may be an issue.
If those images sit within the normal margins of the page, the book will not need bleed, but if they extend to the very edge of the page, the book will need bleed. This point is highlighted in the two pages below:
So keep ‘bleed’ in mind when you select the trim size of your book.
Another factor to consider is the length of your book.
A short book printed in a large trim size may end up looking too thin. A long book printed in a small trim size may end up looking too ‘fat’. More importantly, the spine may not be wide enough to allow for the printing of the title.
Note: KDP requires a minimum of 100 pages to print the title on the spine.
And finally, there’s the question of genre. Books are tactile objects and readers get used to a certain size in their favourite reading material.
Note: books that are either too big or too small for their genre may not be as ‘visible’ to a reader intent on buying a book.
Table of trim sizes – with and without bleed
The following is a table of trim sizes available with KDP:
I hope this proves to be useful. 🙂