Calculating page numbers

What is the proper way to calculate how many pages you'll need in a book?
What I mean is, I drew my next book (selfpublishing, selfprinting) which came out to 128 pages. This is so the last page is on the left with the inside cover on the right. I used the same calculations I found online on ensuring the page count is in multiples of 4 I think. At the very least, 128 was listed as one of the right number of numbers.
Only, today I received an email from my printer saying they had to increase the number of pages to 138! I don't understand what I did wrong. I've also submitted my book to Amazon's on demand printing and noticed they, too, added the extra 10. The kicker is, my book was originally fewer pages and I had to create additional content to fill it up to 128. That was all in vain
Is there a foolproof formula to calculate the correct number of pages? Now my book, a graphic novel, looks ridiculous and unprofessional with 10 extra blank pages and I'd like to avoid this mistake in the future.
I hope someone can enlighten me

What is the reason the printer has given on the email for adding 10 pages?
If the book is saddlestitched  (stapled or stitched on the spine) it needs to be in multiples of 4 so 128 should be fine (including the covers).
If it is going to be perfect bound (pages are glued to the spine) then it can be in multiples of 2.
If you are printing a 128 page saddlestitched book then Iâ€™m not sure why they have added 10 pages.
If itâ€™s 138 then it may be perfect bound and they are having to pad the book out to fill the spine so the pages are not loose or something. Perhaps the spine has been set up too wide? Normally the printer will let you know what spine width to set your cover artwork up as depending on page numbers and paper thickness.
The only wildcard thing I can think of is the pages are a odd size which means they need to use extra paper due to wastage, but that still doesnâ€™t really make much sense with adding extra pages.
Congrats on finishing your book. A 128 page graphic novel sounds like quite an accomplishment

@danielerossi howdy! I can help answer your questions.
TLDR answer: yes, there is a foolproof formula to calculate the correct number of pages. But  and you won't like this part  it changes with every printer.
Page calculation is based upon the print specifications, and each printer has slightly different specifications. Even printondemand (POD) printers like Ingram Spark and KDP have slightly different print guidelines/specifications. The reason for this has to do with the printers (the actual machines) that print the book.
Page calculation also depends on front and back matter that needs to be included before and after the story. So if you plan on the story portion of the book to run 128 pages, you'll need to figure more pages into the actual page count of the book because you'll need to include a title page and a copyright notice page. Most PODs also require that the last page of a book be left blank for their use. So if you figure on a 132 page book, for example, you'll only upload 131 pages of content so that the last page will be left blank for the POD's use, thereby avoiding any extra blank pages in the back.
A good rule of thumb: figure your page count in multiples of 8  that will work no matter if you print in bulk or POD. (Most PODs print in multiples of 4, but some print in multiples of 2. Most traditional, offset printers print in multiples of 8, but some print in multiples of 4.) And remember that if you're printing POD, the last page will need to be left blank.
As far as what went wrong in this specific situation, it's probably best to reach out to the printer and ask them why they needed to add more pages. They should allow you to make any changes before proofing or going to print.

Thanks everyone! Turns out it was a smackingmyforehead moment. I followed up with the printer and it turns out that I had told her that my book was 128 pages completely forgetting that my page 1 starts on page 9! So there arenâ€™t any extra blank pages. Just a proper page count