Why Does KDP Require an Even Page Count?

If you've formatted a manuscript for KDP print and landed on an odd number — say, 227 pages — you may have wondered why the system won't let you upload it as-is, or why your proof came back with a mysterious blank page at the end. This isn't a KDP quirk or an arbitrary software rule. It's a physical constraint that applies to every printed book ever bound, from mass-market paperbacks to hardcover textbooks. Here's exactly why even page counts are non-negotiable, and how to handle it in your own file.