What are the minimum dimensions for mailpieces?

• A. Three and a half inches in height, by five inches in length, and .007 inches thick.
• B. Two inches in height, four inches in length, and .005 inches thick.
• C. Four and a half inches in height, six inches in length, and .01 inches thick.
• D. Three inches in height, five inches in length, and .006 inches thick.

Answer: (A)

The key idea is what size a piece must be at its smallest to still count as a standard letter. USPS sets minimum dimensions so a mailpiece can be handled by processing equipment: height at least 3.5 inches, length at least 5 inches, and thickness at least 0.007 inches. This option lists exactly those minimum values, so it matches the required thresholds.

Other options fail because they have at least one dimension smaller than the minimum (for example, height is only 2 inches or 3 inches in those choices) or thickness below the minimum in one case. A different set with larger numbers isn’t incorrect in practice—it would still meet the minimums—but it does not reflect the smallest allowed dimensions.