Japanese Envelope Sizes & Postage Rates | Quick Reference Chart for Dimensions and Stamp Costs [2026 Edition]

When mailing documents in Japan, have you ever wondered "Is this envelope standard or non-standard mail?" or "How much postage do I need?" The envelope size determines the postal category, which in turn determines how much postage to affix. This article provides quick reference charts for Japanese envelope sizes and postal rates, updated for the October 2024 rate revision.

Postal Rate Quick Reference (Standard & Non-Standard Mail)

First, let's look at the overall postal rate structure. These are the current rates following the October 1, 2024 revision.

Standard Mail (定形郵便物) Rates

Standard mail is a flat ¥110 regardless of weight. Before the revision, rates were split into two tiers — up to 25g (¥84) and up to 50g (¥94) — but now they're unified at ¥110 for anything up to 50g.

Non-Standard Mail, Regular Size (定形外郵便物・規格内) Rates

Regular size requirements: long side ≤ 34cm, short side ≤ 25cm, thickness ≤ 3cm, weight ≤ 1kg.

Non-Standard Mail, Oversize (定形外郵便物・規格外) Rates

Oversize limits: combined length + width + thickness ≤ 90cm, long side ≤ 60cm, weight ≤ 4kg.

Envelope Size & Postal Category Quick Reference

Envelopes That Qualify as Standard Mail

Standard mail size requirements: long side 14–23.5cm, short side 9–12cm, thickness ≤ 1cm, weight ≤ 50g.

Non-Standard Mail (Regular Size) Envelopes

Envelopes that exceed standard mail dimensions but fit within: long side ≤ 34cm, short side ≤ 25cm, thickness ≤ 3cm.

Non-Standard Mail (Oversize) Envelopes

Large envelopes exceeding regular size dimensions.

How to Choose the Right Envelope

Mailing A4 Documents

There are two main ways to send A4 paper (210×297mm):

Tri-fold and send → Nagagata No.3 (120×235mm) = ¥110

When A4 paper is tri-folded, it becomes roughly 99×210mm, fitting neatly into Nagagata No.3. At ¥110 for standard mail, this is the most economical option. Ideal for invoices, notices, and other documents that can be folded.

Send flat → Kakugata No.2 (240×332mm) = ¥140+

For resumes, presentation materials, and other documents that shouldn't be creased, use Kakugata No.2. This qualifies as non-standard mail, costing at least ¥140. Five A4 sheets (~20g) plus the envelope (~15g) totals about 35g, which stays within the ¥140 tier.

Mailing B5 Documents

• Tri-folded → Nagagata No.4 (90×205mm) = ¥110
• Sent flat → Kakugata No.3 (216×277mm) = ¥140+

Mailing Invitations and Greeting Cards

• Yogata No.1 (176×120mm): Commonly used for wedding invitations
• Yogata No.2 (162×114mm): Suitable for greeting cards and thank-you notes

Yogata (Western-style) envelopes have the opening on the long side, making them ideal for horizontally-oriented documents and cards. Both qualify for standard mail at ¥110.

Envelope Weights and Postage Calculation

Postal rates are based on the total weight including the envelope itself, not just the contents.

Envelope Weight Guide

A4 Paper Weight Guide

Common Scenarios: Postage Quick Reference

Tips to Save on Postage

Keep It Within Standard Mail

To send A4 documents for just ¥110, tri-fold them and use a Nagagata No.3 envelope. Up to 10 sheets (~40g) plus the envelope (~5g) = ~45g, which stays within the 50g standard mail limit.

Additional Service Surcharges

FAQ

How much postage does a Nagagata No.3 envelope need?

Nagagata No.3 qualifies as standard mail, so it costs ¥110 for up to 50g. It's the most common business envelope in Japan, fitting A4 paper tri-folded. Before the October 2024 revision, rates were ¥84 (up to 25g) or ¥94 (up to 50g), but now it's a flat ¥110.

How much postage does a Kakugata No.2 envelope need?

Kakugata No.2 qualifies as non-standard mail (regular size). It fits A4 documents flat, and the rate varies by weight: ¥140 for up to 50g, ¥180 for up to 100g. Five A4 sheets can typically be sent for ¥140.

What's the difference between standard and non-standard mail in Japan?

Standard mail (定形郵便) must meet all of these conditions: long side 14–23.5cm, short side 9–12cm, thickness ≤ 1cm, weight ≤ 50g. Exceeding any one condition makes it non-standard mail (定形外郵便). Non-standard mail is further divided into "regular size" (長辺34cm, 短辺25cm, 厚さ3cm, 1kg以内) and "oversize" for anything larger.

What's the cheapest way to mail A4 documents in Japan?

Tri-fold them and send in a Nagagata No.3 envelope for ¥110 (standard mail). Sending flat in a Kakugata No.2 costs ¥140+ (non-standard mail, regular size, up to 50g). Tri-folding is recommended when minimizing cost.

Does the envelope weight count toward postage?

Yes. Postal rates are based on the total weight including the envelope. Nagagata No.3 weighs about 5g; Kakugata No.2 weighs about 13–15g. When you're near a weight threshold, don't forget to factor in the envelope weight.

What changed in the October 2024 postal rate revision?

The biggest change was to standard mail. Before the revision, rates were ¥84 (up to 25g) and ¥94 (up to 50g) in two tiers; after the revision, they unified to a flat ¥110 for up to 50g. Non-standard mail rates also increased across all weight tiers. Postcards went from ¥63 to ¥85.

Summary

Key takeaways for Japanese envelope sizes and postal rates:

• A4 tri-folded → Nagagata No.3 = ¥110 (standard mail) is the most cost-effective
• A4 flat → Kakugata No.2 = ¥140+ (non-standard mail, regular size)
• Postal rates are based on total weight of envelope + contents
• Standard mail is a flat ¥110 for up to 50g (after the October 2024 revision)
• Even standard-sized envelopes become non-standard mail if they exceed 50g

Choose the right envelope for your document type and quantity, affix the correct postage, and send with confidence.