Aspect ratio 1.3 to 2.5

Length divided by height must be between 1.3 and 2.5 or the piece is nonmachinable.

How to fix it

Square and near-square cards pay a nonmachinable surcharge. Keep length/height between 1.3 and 2.5.

Reference

DMM 201.2.1 Nonmachinable Criteria — Letters

Catalog version DMM 2026-07. Always confirm against the current Domestic Mail Manual.