Sometimes you get lucky and find a book with the perfect amount of pages, but the majority of the time your book will have too many and this is totally normal so stop hunting for the 'perfect' book! Unless you get a custom pattern made then it's VERY rare to get a book the perfect amount of pages and height.
For help with how to work out if your pattern will fit the HEIGHT of your book, take a look at this post. Is book height important?
To make your pattern look like it was made for the book and come out looking it's best you need to do a little math. Even if you are thinking of removing the excess pages this still needs to be done evenly from the front and back due to the way pages are attached in sections. If you remove a massive chunk from the front or back it can look unsightly leaving a gaping hole which will not support your fold on that side and can even damage the spine and cover of the book.
To get your start page you first you need to get some numbers from your book and pattern:
e.g. my book has 470 numbered pages
there are 6 sheets without any numbers on, so there are 12 un-numbered pages. (A sheet has 2 sides, page 1 on one side and page 2 on the other so we always double when counting sheets in books and folds on patterns)
This gives me a total of 482 numbered pages.
My pattern has 440 numbered pages.
book size - pattern size = spare pages
482 - 440 = 42 spare pages.
We want to then half this to get an equal amount at the front an the back of the book.
So my start page is page number 21 however, 3 of my un-numbered sheets were at the front, that's 6 numbered pages which are included in my 21 start page, so I deduct 6 from 21 and my actual numbered start page is 15.
Don't worry if this seems confusing, it will soon be second nature. :)
To help you I will attach the centralising sheet for you to download which I give to students of the Cut and fold Masterclass. There is a chart on there with space for you to plug your own numbers in, along with an example so you can copy the method. You can also see me work out a start page on the free cut and fold video and the beginners heart video, in fact any video where I show how to make a book fold I include this at the beginning :)
After folding your pattern you can then decide what to do with those extra pages. Some people leave them in, it is a book after all!
Do you have a 'go to' or favourite method of dealing with extra pages?
If you need any help working out your start page or would like to confirm your workings then do comment below or post in the group.