- 10/11/2026
- AlphaGraphics Conroe
A standard postcard size is 4 × 6 inches. For a card mailed with a retail First-Class postcard stamp, USPS allows dimensions from 3½ × 5 inches to 4¼ × 6 inches. Qualifying commercial First-Class postcards can be larger—up to 6 × 9 inches.