How to Ensure Your Bleed and Cover Width Are Set Correctly for Print

Absolutely,  you might of course ask for 80gsm but they might only stock 90gsm and that changes everything. They'll hardly order in something specially for you as it would cost more. 

As I said - talk to the printers to confirm the spine width, my basic calculator I've used for years in Excel has never steered me wrong, but of course, it's always with the go ahead from the Printers. 

It's only a starting point, then microadjustment of 1mm or 2mm is not a big deal when it comes to production. 

Hi there - you're always so helpful. Thank you. Below is an updated view of the design (first without bleed visible then second with). I had set the spine to 4mm but when someone here mentioned it looked huge, I went back in and checked and it had reset itself to larger. So I made it 4mm again - see screenshots below. In the first screenshot below I've used page select to show you where the spine is. By doing this, I can see the spine won't be big enough to have the book title on it as someone mentioned, which is fine - I'll take it off. It will be perfect bound. Also, after posting here, I did what I should have thought of before - I removed the 2x separate backgrounds that I had (one on front cover and one across both back cover and spine). Then I put one frame across all three pages and applied the green background. I had done the backgrounds separately before as I designed the front cover first with the green background. So I think I'm all set now if I remove the title from the spine and ask the printer how many mm to make the spine.