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Spine Calculator Borked?

Greetings. I'm a new publisher to Lulu but have plenty of experience in layout and publishing in general. My workflow consists of purely working in InDesign and Photoshop. My cover is an all-in-one, made to Lulu's speicifications.


My proof copy is a 6x9 perfect bound trade paperback printed in full color, full bleed, printed on 80# gloss paper with 250 pages. It is a very complex projct. I'm pleased to say that the interior print came out exactly like it should; I was greatly impressed. The cover looks great too, execpt that the size and spine measurements are off consideratbly.


Lulu's "spine calculator" and Advanced Cover tool both told me to use a cover size of 12.88 in by 9.25 in. My spine starts 6.125 in from the left and is 0.625 in wide. Those are the setting I used. However, in the final product my spine starts correctly but is far too large; the back cover "rolls over" onto the spine.


My printed produt's spine (again, on Lulu's full color 80# paper) is actually ~.75 in wide, or ~19 mm thick. A signifigant gap.


Going to a third-party site ( I entered similiar settings tells me that my spine thickness should be 0.684 in which is a little closer to my actual output. Putting in 100# interior paper thickness gives me a spine thickness of 0.854 in, which is very close to what I actually have in front of me.


So, the question: does Lulu's spine calculator work for "Standard, Perfect Boudn Paperback," Full Color on 80# paper correctly? I printed out using their speificiations and my spine is NOT .0625 thick. My physical copy has a spine that is ~0.75 in thick or ~19 mm.


  • Humm, kind of surprised no reponses. I emailed tech support as well.


    How bout as an exercise folks tell me their spine thickness for a 6x9 perfect bound trade paperback, full color, 80# paper, 250 pages? All I care is about the spine width and the fairly large discrepency.

  • potetjppotetjp Professor

    I never bother with that. I let the Lulu cover wizard do the job. I pick the background colors, upload my front cover picture, my back cover blurb, my portrait and my bio. Lulu does the rest, and well. 

  • The complexity of my cover is as such that it is designed in InDesign. One cover inputting is my only option. Hence, I am wholly dependent upon Lulu providing me with correct page sizing, spine location, and spine thickness. The smallest discrepency causes issues.


    Fortunately I've heard from Lulu tech support and supplied pictures of my ".625 in" spine taken against a ruler, clearly showing .75 in of thickness. So looks like tech support is "on the job!"

  • potetjppotetjp Professor
  • After sending in pictures and conversing with tech support their position was that the spine calculator was fine, the printer made a mistake. The tech support person speculated that the spine was not compressed tightly enough, thus accounting for the increased thickness.


    I have the benefit of holding the book and the spine and tightness feels excellent. A printer error is possible, but I think it's more likely they inadvertantly used heavier paper. Using 100# paper would roughly equate to the spine thickness of my book.


    In any case, Lulu is sending me another copy at no cost. The presuption being that we won't have an error. My spine location and measurements are identical.


    I'll followup when I have the second printing to compare against the first.

  • potetjppotetjp Professor

    Thanks. Yes, keep us informed; your case is interesting.

  • Just recieved the revised print. No change. Exact same thickness. At this point I have zero confidence in Lulu's spine calculator--at least for any graphical work that requires a level of precision.


    To be clear, it isn't that the spine doesn't line up--printer shifts happen and that's just a fact of life--it's that the physical thickness of the book (spine) is larger than what the calculator says it'll be. And not by just a little; a LOT. My 250 page 0.625 in thick book is actualy 0.71 in, or just over 2mm larger. On a spine, 2mm of unintetntional bleed is very noticable.


    Sure, I've books on my shelf (printed via traditional means) that don't have perfect spines, but their offset is less than a mm.


    Rewrote tech support and provided them with updated pictures.


    [Edit] Tech support is going to re-order and walk the book through with the printer to understand why the book is thicker than the calculator shows.


    Also, I feel obligated to mention that the internals look great, the binding is fine, and the cover printing is all top-notch. Were it not for the unusual weight the book is putting on (need a diet!) everything would be great.

  • potetjppotetjp Professor

    I have a difficult question. Is the thickness of a leaf in the paper of your book given somewhere, (preferably in the metric system as the old measures can be a great source of errors)? If you had it, you could calculate how many leaves there are in the difference between the actual spine width and the theoretical one.

    Are you sure the number of pages, including blank pages, of your printed book is the same as the one you had in mind?

  • potetjp, I'm not sure I could. I'm sure about the page counts, yes.


    I have not heard back from Lulu support nor seen/received their last SC test print. I have, however, received my HC proof which adds even more questions.


    The HC design is (70#):

    Spine Width: 0.875in

    Cover Size: 14.63 x 10.75in

    Spine Begins: 6.875in


    Book arrived and cover is as you would expect. A slight amount of shift but within acceptable tolerance. In short, as designed and acceptable. Job well done.


    The interesting part is that the HC is actually >thinner< than the SC! (Also weighs less) The 70# paper in the HC is noticably lighter weight than the supposed 80# paper in the SC. Dramatically so. If I had to speculate, I'd say the paper weight on the SC is closer to 100#.


    I will take some pictures and submit to Lulu to hopefully help them troubleshoot the issue. It seems this is less an issue with the spine calculator and more an issue with the printer (twice) printing the SC on the wrong weight of paper.
  • potetjppotetjp Professor

    Abulia a écrit :


    the HC is actually >thinner< than the SC! (Also weighs less) The 70# paper in the HC is noticably lighter weight than the supposed 80# paper in the SC. Dramatically so. If I had to speculate, I'd say the paper weight on the SC is closer to 100#. 

    Yes, you must be right. If the hard-cover copy is lighter that the soft-cover one for the same number of pages, there is no doubt its paper is heavier. How bizarre!


  • I'd like to follow-up with the "solution." First, Lulu steadfastly remains that their spine calculator is "correct."


    The SC books that I have made where the spines don't line up? Well...

    "We've gotten some additional information from our print vendor that sheds a little light on the situation. This vendor, for the type of product that this book is, provides amazing paper that's actually a kind of high quality photobook paper, better than one would expect to get normally in this kind of book. The problem with it is that it is a bit thicker than our specification calls for, and this greater thickness makes the spine wider. Since it's such good paper, though, we don't want them to change their paper."


    "The specification for this product is 400 ppi for the interior paper, and the paper that is being used is 386 ppi, so slightly thicker."


    So the Lulu spine calculator is "correct" even though it will not create a spine thickness that will account for 386 ppi (thicker) paper.


    Lulu has given me no indication that they will either a) correct the spine calculator or b) have the printer rever to the proper 400 ppi paper.


    So caveat emptor!

  • Hello,

    Did you eventually find a solution for this. I am having the exact same problem Smiley Sad
  • This is an old thread. Read the more recent replies to such problems on the forum.

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