Whether you are designing direct mail marketing campaigns, issuing VIP event invitations, sending promotional vouchers, or printing souvenir art cards in Japan, understanding local postcard size Japan standards is critical.
In Western countries, standard postcard dimensions vary between 4″ × 6″ in North America and A6 in Europe. In Japan, however, domestic post offices (*Japan Post / Nippon Yūbin*) enforce strict dimensional, weight, and layout rules for official postcards—known locally as Hagaki (葉書).
Designing a postcard to non-standard dimensions or omitting required Japanese postal markings can lead to higher postage costs, processing delays, or delivery rejection.
This 2026 guide covers everything foreign businesses, marketing teams, and creators need to know about postcard size Japan standards—including Hagaki measurements, paper weights, Japan Post mailing rules, artwork bleed setup, and custom printing in English.
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1. What Is the Standard Postcard Size in Japan?
The universal standard postcard size in Japan is the official Hagaki (100 × 148 mm).
Hagaki Size Specifications
- Millimeters: 100 × 148 mm
- Centimeters: 10.0 × 14.8 cm
- Inches: 3.94 × 5.83 inches
- Aspect Ratio: 1 : 1.48
This dimensions standard applies to official government postal cards, domestic holiday greeting cards (*Nendajō* 年賀状), corporate direct mail cards, and event promo cards across Japan.
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2. Comparing Japanese Postcard Sizes: Hagaki vs. A6 vs. Ofuku Hagaki
While 100 × 148 mm Hagaki is standard for domestic mailing, commercial printers in Japan produce several distinct postcard formats:
| Postcard Format | Dimensions (mm) | Aspect / Description | Primary Application |
|---|---|---|---|
| :--- | :--- | :--- | :--- |
| Standard Hagaki (官製はがき / 私製はがき) | 100 × 148 mm | Official Japan Post standard size | Direct mail marketing, VIP event invites, thank-you cards |
| ISO A6 Postcard | 105 × 148 mm | 5mm wider than standard Hagaki | Promotional hand-outs, international export cards |
| Double Hagaki (*Ofuku Hagaki* 往復はがき) | 200 × 148 mm (Folded to 100×148mm) | Two attached cards with center crease | RSVP reply cards, event registrations, survey cards |
| Long / Large Postcard (*Jumbo Hagaki*) | 120 × 235 mm or 107 × 220 mm | Elongated envelope size | High-impact direct mail, luxury brand promotions |
Hagaki vs. Western 4 × 6 Inch Postcards
- Japanese Hagaki: 100 × 148 mm (3.94″ × 5.83″)
- US Standard Postcard: 101.6 × 152.4 mm (4.0″ × 6.0″)
*Crucial Warning:* Submitting artwork set to US 4″ × 6″ (101.6 × 152.4 mm) for domestic Japanese mailing will exceed the maximum 100 × 148 mm Hagaki postal boundary, causing Japan Post to reclassify the item as a letter (*Dikeigai*), significantly increasing postage costs. Always resize artwork to 100 × 148 mm for Japanese distribution.
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3. Japan Post Mailing Rules & "郵便はがき" Requirements
To mail custom-printed postcards (*Shisei Hagaki* 私製はがき) through Japan Post at the standard domestic postcard rate (¥85), your printed cards must comply with four strict rules:
1. Mandatory Text Marking
The top or left edge of the address side (*Atemen*) must display the words "郵便はがき" (in Japanese Kanji) or "POST CARD" (in English capital letters). If this marking is missing, Japan Post charges full sealed-letter postage.
2. Physical Weight Limits
- Minimum Weight: 2.0 grams per card
- Maximum Weight: 6.0 grams per card
3. Paper Thickness & Rigidity
Japan Post requires postcards to be sufficiently rigid to pass through automated sorting machines. Paper thickness must fall between 0.2 mm and 0.9 mm. In commercial printing terms, this translates to paper ream weights of 180 kg to 220 kg (*Shiroku-ban* 四六判).
4. Postal Code Box Alignment (*Yūbin Bangō*)
If printing domestic Japanese mailing addresses, the front of the card should feature the standard 7-digit postal code boxes printed in fluorescent red/orange ink or black outline along the top edge.
Explore custom card options on our Postcards product page.
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4. Promotional Postcards vs. Direct Mail Postcards
Depending on how your postcards will be distributed, paper finishes and coating choices differ:
1. Direct Mail Marketing Postcards
- Front Side (Promotional): Full-color graphics, product imagery, and headline offers printed with Matte or Gloss PP Lamination for eye-catching visual punch.
- Back Side (Mailing Address): Uncoated matte paper stock so address labels, ballpoint pen notes, or postal barcodes can be applied without smudging.
2. Handout & Package Insert Postcards
When handing out promotional postcards at trade show booths like Tokyo Big Sight or inserting discount vouchers into customer shipments, mailing regulations do not apply. You can utilize heavy 220kg silk cardstock with double-sided lamination or spot UV finishes.
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5. Technical Pre-Press Setup: Bleed, Paper Weights & Color Profiles
To prepare print-ready PDF files for custom postcard production in Japan, follow these technical guidelines:
- Canvas Size with Bleed: Set digital canvas to 106 × 154 mm (100 × 148 mm final trim size plus 3 mm bleed on all 4 sides).
- Safe Safe Zone: Keep all critical text, logos, and QR codes at least 5 mm inside the 100 × 148 mm trim boundary.
- Paper Weight Selection:
- 180 kg (~210 gsm): Standard postcard stock; lightweight yet durable.
- 220 kg (~256 gsm): Premium heavy cardstock; excellent tactile weight for luxury marketing.
- Color Profile: Convert all RGB images to CMYK (Japan Color 2001 Coated).
- Resolution: Set artwork resolution to 300 DPI minimum.
- Font Outlining: Outline all vector fonts to prevent typography shifts.
If your design files require prepress adjustments, Print Japan provides free pre-flight file checks and fixes on every order.
If you also require standard Japanese executive business cards, explore our guide on Bilingual Business Cards Printing in Japan.
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Frequently Asked Questions
What is the standard postcard size in Japan (Hagaki)?
The official Japanese standard postcard size (*Hagaki* 葉書) is 100 × 148 mm (3.94 × 5.83 inches). This specific size qualifies for standard domestic postage rates (¥85 as of recent Japan Post rate updates) when marked correctly.
What text marking is required on postcards mailed via Japan Post?
To qualify for standard domestic postcard postage in Japan, the address side must display the text "郵便はがき" (Yuubin Hagaki) or "POST CARD" clearly along the top or left edge.
What paper weight is used for custom printed postcards in Japan?
Custom commercial postcards in Japan are typically printed on 180kg to 220kg cardstock (approx. 210–256 gsm) in silk, matte, or heavy art board finishes to ensure rigidity during handling.
Can I print international sizes like Western 4x6 inch postcards in Japan?
Western 4 × 6 inch postcards (101.6 × 152.4 mm) are slightly larger than official Japanese Hagaki (100 × 148 mm). While they can be printed for promotional handouts, mailing non-standard sizes via Japan Post may incur higher first-class letter rates.
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Order Custom Postcards in Japan with Print Japan
Need high-quality postcards printed to exact Japanese Hagaki dimensions with guaranteed fast delivery across Japan? Print Japan handles your order in 100% English—from pre-press file checks to direct shipping.
- Request an Instant Quote: Online Quote Request Form
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- Explore Products: View our Postcards, Business Cards, and Flyers & Leaflets.
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