US Trends

what size is a postcard

Quick Scoop: What Size Is a Postcard?

The standard postcard size is 4″ × 6″ (102 × 152 mm) , the dimensions most commonly used for direct‑mail promotions, holiday greetings, and tourism snapshots. But “postcard” isn’t a single fixed size—postal services and printers accept a range, from tiny 3.5″ × 5″ cards up to jumbo 8.5″ × 11″ “flat” mailers, as long as they stay under ¼ inch thick.

📏 Common Postcard Dimensions (U.S. & International)

Category / Style| Inches (W × H)| Millimeters (approx.)| Typical Use
---|---|---|---
Standard| 4″ × 6″| 102 × 152 mm| Direct mail, promos, vacation snapshots 1
A6 (Europe/UK standard)| 4.1″ × 5.8″| 104 × 148 mm| Event invites, seaside postcards 15
Medium| 5″ × 7″| 127 × 178 mm| Marketing campaigns, birthday cards 13
Large| 6″ × 8″ or 6″ × 9″| 153 × 203 / 153 × 229 mm| High‑impact flyers, real‑estate mailers 9
Jumbo / Flat| 6″ × 11″ or 8.5″ × 11″| 153 × 280 / 216 × 279 mm| Detailed brochures, catalog inserts 19
Mini / A1| 3.5″ × 5″| 89 × 127 mm| Quick reminders, business‑card‑sized notes 4

Forum buzz (2025–2026): Many direct‑mail marketers now “skip the tiny 4×6” and default to 6″ × 9″ because it costs the same postcard postage (USPS First‑Class Postcard rate, $0.43 as of 2026) but gives 2.25× the design space.

📬 USPS Minimum & Maximum Rules (2026)

To be processed as a postcard (not a letter or flat), the card must:

  • Be rectangular and uniformly thick.
  • Measure at least 3½″ × 5″ and no more than 6″ × 4¼″ for the cheapest postcard rate.
  • Stay under 0.25″ thick and under 4.2 oz weight.
  • Larger formats (6″ × 11″, 8.5″ × 11″, etc.) still mail as postcards functionally , but they are rated at the Standard/First‑Class Letter or Flat postage tiers, which cost more.

🎨 Design Quick Tips (Trending in 2026)

  1. Keep it simple. A small canvas overwhelms readers; highlight 2–3 key points plus a strong call‑to‑action (visit site, follow social, leave a review).
  1. Add fresh, local content. Forum discussions favor recipe swaps, fun facts about the pictured location, or “latest news from my city” snippets.
  1. Mind the bleed. Printers usually require a 0.125″ bleed on all sides; a 4″ × 6″ final card should be set up as 4.25″ × 6.25″ with critical info inside the safe zone.
  1. Pixel dimensions (300 dpi). For digital files: 4″ × 6″ → 1247 × 1847 px; 6″ × 9″ → 1805 × 2705 px.

💡 Which Size Should You Choose?

  • 4″ × 6″ : Perfect for appointment reminders, tweet‑sized messages, or tight budgets.
  • 5″ × 7″ : Great balance of space and affordable postage; ideal for birthdays and small business promos.
  • 6″ × 9″ : Best value for marketing—same postcard rate as 4″ × 6″ but nearly double the real estate.
  • 6″ × 11″ or larger : Use when you need charts, multiple images, or folded‑brochure content; expect letter/flat postage.

Note: Postage rates change annually; as of March 2026 the First‑Class Postcard rate is $0.43, while large‑format cards start at $0.73–$1.00 depending on weight and automation discounts.

Information gathered from public forums or data available on the internet and portrayed here.