For Saddle Stitch and Coil Softcovers: There is no spine for these binding types.For Perfect Softcovers: (Page Count / 444) + 0.06 = Spine Width in inches or for Comic Books and Magazines: (Page Count / 460) + 0.06” = Spine Width for 460 PPI paperFor Casewrap Hardcovers: See Spine Width Table below:Page CountSpine Width (Inches)Spine Width (mm)0-24N/AN/A24-840.25684-1400.513140-1680.62516169-1940.687517195-2220.7519223-2500.812521251-2780.87522279-3060.937524307-334125335-3601.062527361-3881.12529389-4161.187530417-4441.2532445-4721.312533473-5001.37535501-5281.437537529-5561.538557-5821.562540583-6101.62541611-6381.687543639-6661.7544667-6941.812546695-7221.87548723-7501.937549751-778251779-8002.0625528002.12554