Envelopes and mailPS-07
What Are the Envelope Sizes in Japan? Nagagata, Kakugata and Yogata Dimensions, What Paper Fits, Kaku 2 vs Kaku A4, and Japan Post Mail Classes
You choose an envelope size by two things: the paper you put in and the postal class. The size table comes first, followed by folding, clearance, Kaku 2 vs Kaku A4 and the conditions for standard-size mail.
In this article (12 sections)
- Conclusion: which envelope size should you choose?
- How do Nagagata, Kakugata and Yogata envelope sizes differ?
What paper fits each envelope size, and how do you fold it?2
- How do Kaku 2 and Kaku A4 envelope sizes differ?
How does envelope size decide standard or non-standard mail in Japan?1
- How do you shrink paper to fit an envelope size?
- Which envelope sizes are in JIS, and which are not?
- What are common mistakes with envelope sizes?
- What terms come up with envelope sizes?
What else should you know about envelope sizes?4
Frequently asked questions about envelope sizes6
- Sources
Envelope sizes in Japan are named by three shapes, Nagagata (long), Kakugata (square) and Yogata (Western-style), plus a number. Naga 3 (Nagagata No. 3) and Kaku 2 (Kakugata No. 2) are the usual short forms.
When you choose an envelope size, you look at two things: whether the paper fits inside, and which postal class the envelope falls into.
Even for A4, the envelope changes depending on whether you fold the paper. When the envelope changes, the postage class can change too.
Here is the key point. Decide the envelope size as a set: "the paper you put in" and "the postal class".
This article covers the following.
- Envelope sizes for Nagagata, Kakugata and Yogata, and the paper that fits each
- How to fold A4, B5, A5 and B4, and how to calculate the clearance
- How Kaku 2 and Kaku A4 differ, and how to choose between them
- Japan Post's standard-size and non-standard-size classes, and how many sheets fit in 50g
- Envelope sizes in the JIS table, and sizes that are not in it
The dimensions are shown in a table based on the JIS S 5502 table published by Japan Post. How to write the address is not covered.
Conclusion: which envelope size should you choose?
| Envelope | mm (w × h) | Fits | Japan Post class (≤1 cm thick, ≤50 g) |
|---|---|---|---|
| Nagagata No. 2 | 119 × 277 | A4 folded in three, B5 folded lengthwise | Non-standard (within size) |
| Nagagata No. 3 | 120 × 235 | A4 folded in three | Standard (teikei) |
| Nagagata No. 4 | 90 × 205 | B5 folded in four | Standard (teikei) |
| Nagagata No. 6 | 110 × 220 | A4 folded in three | Standard (teikei) |
| Nagagata No. 40 | 90 × 225 | A4 folded in four | Standard (teikei) |
| Kakugata No. 0 | 287 × 382 | B4 flat | Non-standard (oversize) |
| Kakugata No. 2 | 240 × 332 | A4 flat | Non-standard (within size) |
| Kakugata A4 | 228 × 312 | A4 flat | Non-standard (within size) |
| Kakugata No. 20 | 229 × 324 | A4 flat | Non-standard (within size) |
| Kakugata No. 3 | 216 × 277 | B5 flat | Non-standard (within size) |
| Kakugata No. 4 | 197 × 267 | B5 flat | Non-standard (within size) |
| Kakugata No. 5 | 190 × 240 | A5 flat | Non-standard (within size) |
| Kakugata No. 6 | 162 × 229 | A5 flat | Non-standard (within size) |
| Kakugata No. 7 | 142 × 205 | B6 flat | Non-standard (within size) |
| Kakugata No. 8 | 119 × 197 | B5 folded in three | Standard (teikei) |
| Yogata No. 1 | 176 × 120 | Postcard, A4 folded in four | Standard (teikei) |
| Yogata No. 2 | 162 × 114 | Postcard, A4 folded in four | Standard (teikei) |
| Yogata No. 4 | 235 × 105 | A4 folded in three (landscape) | Standard (teikei) |
| Yogata No. 6 | 190 × 98 | B5 folded in three (landscape) | Standard (teikei) |
| Yo-nagagata No. 3 | 235 × 120 | A4 folded in three (landscape) | Standard (teikei) |
Source: Japan Post, Envelopes conforming to JIS S 5502:2010 (size); Japan Post rate table (mail class) / JIS S 5502, Japan Post mail size classes / Customary size used by envelope makers (not in the JIS S 5502:2010 size table)
The mm values in the table are in the order "width × height". Yogata envelopes are wide, so, as in the JIS table, the longer side is written first.
The three most common combinations are these.
- A4 folded in three: Nagagata No. 3 (Naga 3)
- A4 sent flat: Kakugata No. 2 (Kaku 2)
- B5 sent flat: Kakugata No. 3 (Kaku 3)
If in doubt, a Naga 3 or a Kaku 2 is enough for A4 documents. Decide first whether you may fold the paper, and the choice is quick.
The "Japan Post class" in the table applies when the item is up to 1cm thick and up to 50g. If the contents are thick or heavy, check the mail section later in this article.
How do Nagagata, Kakugata and Yogata envelope sizes differ?
Envelope sizes fall into three groups by shape. Nagagata is long and narrow, Kakugata is close to square, and Yogata is wide.
| Shape | Look | How paper usually goes in | Main uses |
|---|---|---|---|
| Nagagata (long) | Tall and narrow | Paper folded in three or four | Invoices, notices, cover letters |
| Kakugata (square) | Close to square | Paper put in flat | Job applications, contracts, booklets |
| Yogata (Western-style) | Wide | Cards or folded paper | Invitations, greeting letters, cards |
The number shows the size within the same shape. A bigger number does not always mean a smaller envelope. Kakugata No. 20 is between Kakugata No. 2 and Kakugata No. 3 in size.
Some Nagagata and Yogata envelopes have the same dimensions and differ only in where the flap is. Nagagata No. 3 and Yo-nagagata No. 3 are the same size, as the table shows.
Nagagata envelopes usually open on a short side, and Yogata envelopes on a long side. This changes the window position and the print direction, so check before you order.
What paper fits each envelope size, and how do you fold it?
Whether paper fits an envelope size is a matter of comparing the folded paper with the envelope's dimensions. The clearance is calculated in the table below.
| Paper and fold | Folded size (calculated) | Envelope it fits | Clearance (width, height) |
|---|---|---|---|
| A4 folded in three | 99 × 210mm | Nagagata No. 3 | 21mm, 25mm |
| A4 folded in three | 99 × 210mm | Yogata No. 4 (landscape) | 6mm, 25mm |
| A4 folded lengthwise in four | 74 × 210mm | Nagagata No. 40 | 16mm, 15mm |
| A4 folded in four as a cross | 105 × 149mm | Yogata No. 2 (landscape) | 13mm, 9mm |
| B5 folded in three | 86 × 182mm | Nagagata No. 4 | 4mm, 23mm |
| B5 folded lengthwise in four | 64 × 182mm | Nagagata No. 4 | 26mm, 23mm |
| A4 not folded | 210 × 297mm | Kakugata No. 2 | 30mm, 35mm |
| A4 not folded | 210 × 297mm | Kakugata A4 | 18mm, 15mm |
| B5 not folded | 182 × 257mm | Kakugata No. 3 | 34mm, 20mm |
| A5 not folded | 148 × 210mm | Kakugata No. 6 | 14mm, 19mm |
| B4 not folded | 257 × 364mm | Kakugata No. 0 | 30mm, 18mm |
The paper dimensions are in the table below. For a fold in three, the long side is divided by 3; for a fold in four, by 4.
| Size | mm (w × h) |
|---|---|
| A4 | 210 × 297 |
| A5 | 148 × 210 |
| B4 | 257 × 364 |
| B5 | 182 × 257 |
Source: JIS P 0138, ISO 216, ANSI/ASME Y14.1
Envelope dimensions are outside measurements. The seams take up a little room, so the usable width inside is slightly narrower.
Combinations with less than 5mm of clearance are hard to fill, so it is safer to avoid them. B5 folded in three in a Naga 4 leaves only about 4mm of width.
What envelope size fits A4 folded in three?
The envelope that takes A4 folded in three most easily is the Nagagata No. 3 envelope. For a landscape envelope, Yo-nagagata No. 3 is the same size.
Folding A4 in three gives 297 ÷ 3 = 99, a piece of paper 99mm tall. A Nagagata No. 3 leaves 21mm to spare in width.
It also fits a Yogata No. 4, but the clearance is 105 − 99 = 6mm. With several sheets stacked, the corners can catch.
What envelope size takes A4 without folding?
To put A4 in without folding, use Kakugata No. 2, Kakugata A4 or Kakugata No. 20. All three are non-standard (within size).
The difference among the three is the clearance. Kaku 2 has the most room, and Kaku A4 is the tightest fit.
If you send the paper inside a clear folder, a Kaku 2 is the safe choice. An A4 clear folder is made slightly larger than an A4 sheet.
How do Kaku 2 and Kaku A4 envelope sizes differ?
A Kakugata No. 2 envelope (Kaku 2) is 12mm wider and 20mm taller than a Kaku A4. Both take A4 without folding.
| Point | Kakugata No. 2 (Kaku 2) | Kakugata A4 (Kaku A4) |
|---|---|---|
| Clearance with A4 inside | 30mm wide, 35mm high | 18mm wide, 15mm high |
| In the JIS table | Yes | No (maker's customary size) |
| Japan Post class | Non-standard (within size) | Non-standard (within size) |
| Suits | Thicker documents, documents in a clear folder, booklets | A few A4 documents |
| Choose it when | You want room for thick contents | You do not want the papers to slide around |
The differences are 240 − 228 = 12 and 332 − 312 = 20.
The postal class is the same, so the envelope size does not change the postage class. What sets the postage is not the envelope but the weight with the contents inside.
Documents you do not want to crease, such as job applications or contracts, can go in either. The paper shifts less inside a Kaku A4.
A Kaku A4 is a close fit, so thick documents make the flap hard to close. If the contents are thick, a Kaku 2 is easier.
How does envelope size decide standard or non-standard mail in Japan?
If the envelope size is within Japan Post's standard range, it is standard-size mail (teikei). Beyond that range, it becomes non-standard-size mail (teikeigai).
In Japan Post's rate table, letters (first-class mail, daiisshu yubinbutsu) are classed as follows.
| Class | Size | Thickness | Weight |
|---|---|---|---|
| Standard-size mail | Rectangle, length 14 to 23.5cm, width 9 to 12cm | Up to 1cm | Up to 50g |
| Non-standard (within size) | Long side 34cm or less, short side 25cm or less | Up to 3cm | Up to 1kg |
| Non-standard (oversize) | Long side 60cm or less, three sides totaling 90cm or less | Within the three-side total | Up to 4kg |
The classes in the size table were set by checking each envelope's dimensions against these ranges. Naga 3 and Yo-naga 3 are exactly the upper limit of the standard size.
All Kakugata envelopes except Kaku 8 are wider than 12cm. That is why Kaku 2, Kaku A4 and Kaku 3 are all non-standard.
An envelope whose long side is over 34cm, such as Kaku 0, is non-standard (oversize). Oversize mail is in a higher postage class than mail within size.
Postage amounts may be revised. Check Japan Post's rate table (letters and postcards) before you mail.
How many A4 sheets fit in 50g for standard-size mail?
About 10 sheets of ordinary copy paper fit within the 50g limit for standard-size mail. Weigh the envelope together with the paper.
The weight of one A4 sheet is area × grammage (g/m², the weight per square meter). 0.21 × 0.297 × 70 ≈ 4.4g.
| A4 sheets (70g/m²) | Paper weight only (calculated) | With the envelope added |
|---|---|---|
| 1 sheet | About 4.4g | Well within the 50g standard limit |
| 5 sheets | About 21.8g | Well within |
| 8 sheets | About 34.9g | Usually within |
| 10 sheets | About 43.7g | May go over, depending on the envelope |
| 11 sheets | About 48.0g | Almost always over |
Typical grammage values are shown below.
| Grammage (g/m²) | Typical use |
|---|---|
| 65 | Copiers and printers |
| 67 | Copiers and printers (50% recycled pulp) |
| 81.4 | Leaflets, flyers, magazine text pages |
| 104.7 | Leaflets, posters |
Source: FUJIFILM Business Innovation, "EP" (65 g/m², 91 μm) / FUJIFILM Business Innovation, "SG" (67 g/m², 93 μm) / FUJIFILM Business Innovation, "Paper thickness" (grammage and typical uses)
The thicker the paper, the heavier each sheet and the fewer sheets fit. At around 10 sheets, weigh the envelope on a scale before you seal it.
How do you shrink paper to fit an envelope size?
If a document does not fit the envelope size, you can shrink it and print it again. The calculator below gives the scale.
In the tool's "scale for enlarging or reducing", choose the original paper and the paper you will print on. From B4 to A4, the calculation is as follows.
- Width: 210 ÷ 257 ≈ 0.817
- Height: 297 ÷ 364 ≈ 0.816
Set the smaller of the two, about 81.6%, and a B4 document fits on A4. Once it is A4, you can send it in a Naga 3 or a Kaku 2.
Shrinking also makes the text smaller. To spare the reader's eyes, it is safer to stay at around 80% or larger.
Which envelope sizes are in JIS, and which are not?
Envelope names and dimensions are set by JIS S 5502 (envelopes). Envelopes sold in shops, though, include sizes that are not in the JIS table.
The JIS S5502:2010 table published by Japan Post includes the following envelopes.
| Shape | Numbers in the JIS table |
|---|---|
| Nagagata | No. 2, No. 3, No. 4, No. 6, No. 40 |
| Kakugata | No. 0, No. 2, No. 3, No. 4, No. 5, No. 6, No. 7, No. 8, No. 20 |
| Yogata | No. 1, No. 2, No. 4, No. 6 |
In this article's size table, Kakugata A4 and Yo-nagagata No. 3 are not in the JIS table. Both are customary sizes that makers widely produce.
Envelopes with other numbers not in the table, such as Nagagata No. 1 and Kakugata No. 1, are also sold. Envelopes not in the JIS table can differ by a few mm from maker to maker.
When you order, check the size in mm as well as the name. For window envelopes, also check the window position.
What are common mistakes with envelope sizes?
The most common one is mailing a Kaku 2 with standard-size postage. Mistakes people often ask about are in the table below.
| Mistake | What happens | Fix |
|---|---|---|
| Putting standard-size postage on a Kaku 2 | The postage is short | Kaku 2 is non-standard. Check the postage by weight |
| Putting a thick booklet in a Naga 3 | It goes over 1cm thick and becomes non-standard | Switch to a Kakugata envelope |
| Mailing without weighing | It goes over 50g and becomes non-standard | Weigh it at around 10 sheets |
| Putting B5 folded in three in a Naga 4 | Only about 4mm of clearance, hard to insert | Fold it in four, or use a Naga 3 |
| Putting A4 folded in three in a Yo 4 | 6mm of clearance, the corners catch | Use a Naga 3 or a Yo-naga 3 |
| Putting a clear folder in a Kaku A4 | It may not fit | Use a Kaku 2 |
| Ordering by name only | Numbers not in JIS differ in size | Check the size in mm too |
Weighing the filled envelope once before you mail it prevents almost all of these mistakes.
What terms come up with envelope sizes?
| Term | Meaning | Source |
|---|---|---|
| Nagagata (long) | Tall, narrow envelopes, such as Naga 3 and Naga 4 | JIS S 5502 |
| Kakugata (square) | Envelopes close to square, such as Kaku 2 and Kaku 3 | JIS S 5502 |
| Yogata (Western-style) | Wide envelopes, such as Yo 2 | JIS S 5502 |
| Number (go) | The size within one shape | JIS S 5502 |
| Standard-size mail (teikei) | Letters within a set size and weight | Japan Post rate table |
| Non-standard-size mail (teikeigai) | Letters outside the standard size, split into within size and oversize | Japan Post rate table |
| First-class mail | Letters (sealed mail and the like) | Domestic Mail Terms and Conditions |
| Grammage | Weight of paper per 1m² (g/m²) | JIS P 8124 |
| Customary size | A size widely used in the industry, not a standard | General term |
What else should you know about envelope sizes?
How do you say Naga 3 and Kaku 2?
Naga 3 is usually called "naga-san" and Kaku 2 "kaku-ni" (san and ni are Japanese for 3 and 2). Yo 2 is "yo-ni".
The formal names are Nagagata No. 3 and Kakugata No. 2. On order forms and quotes, write the formal name and the size in mm side by side, so nobody mixes them up.
What envelope size do you use for a postcard?
To put a postcard in an envelope, a Yogata No. 2 fits it just right. A Yogata No. 1 also works.
A postcard inside an envelope cannot be sent at the postcard rate. See postcard size for details.
Where can you see paper dimensions all together?
You can see the A and B series together in the paper size list.
You choose an envelope from the paper's dimensions, so check the paper first. For US Letter documents, see the comparison in Letter size vs A4.
Where do this site's figures come from?
The envelope dimensions are based on the JIS S 5502 table published by Japan Post. The tables and the tool read the same data.
How we check figures and our editorial policy are described in About this site.
Envelopes and mailWhat Size Is a Japanese Postcard in cm? Pixels, Aspect Ratio, Japan Post Rules and Making Your OwnJapanese postcard size in cm and pixels by dpi, vs A6 and L-size, aspect ratio, Japan Post rules for return and private postcards, bleed, A4 layout and overseas cards.
Paper sizesPaper Size Chart: A, B, Letter, Photo and Postcard Sizes, Uses, How to Choose and ScalingPaper sizes in mm, cm and inches with uses. A and B series rules, ISO vs JIS B sizes, Letter, photo, postcard and business card sizes, choosing by use and scaling.
ConversionsHow many pixels is A4? A chart by dpi, how the calculation works, and how to make print dataA4 pixel counts at 72, 150, 300 and 350 dpi, how to calculate them, the dpi each use needs, Word, PowerPoint and Photoshop settings, phone photos, and common mistakes.Frequently asked questions about envelope sizes
What is the most common envelope size?
The Naga 3, for A4 folded in three, and the Kaku 2, for A4 put in flat, are the most used.
For B5 documents, choose a Naga 4 or a Kaku 3.
What is the size of a Kaku 2 envelope in cm?
The Kaku 2 dimensions are in the conclusion table. It takes A4 without folding.
With A4 inside, there is 30mm of clearance in width and 35mm in height.
What envelope size fits A4?
If you fold it, a Naga 3. If you do not, a Kaku 2, Kaku A4 or Kaku 20.
A4 folded in four as a cross also fits a Yo 2.
What is the largest envelope you can send as standard-size mail?
The Naga 3 and the Yo-naga 3. Both are exactly 23.5 × 12cm, the upper limit for standard-size mail.
With the contents inside, keep it within 1cm thick and 50g.
Is a Kaku 2 non-standard-size mail?
Yes. A Kaku 2 is wider than 12cm, so it is non-standard (within size).
Up to 3cm thick and 1kg, it goes at the within-size rate.
How much is the postage for an envelope?
It depends on the weight and the class. Amounts may be revised, so check Japan Post's rate table.
The domestic rate table (letters and postcards) lists the rates for standard-size and non-standard-size mail.
Sources
- Conditions for envelopes conforming to JIS S5502:2010 "Envelopes" (Japan Post, in Japanese. Envelope names and sizes)
- Domestic rate table (letters and postcards) (Japan Post, in Japanese. Size, thickness and weight limits for standard-size and non-standard-size mail)
- Basic conditions for standard-size mail and postcards (size and weight) (Japan Post, in Japanese. Size and weight ranges)
- Domestic Mail Terms and Conditions (Japan Post, in Japanese. Definition of first-class mail)
- JIS S 5502 Envelopes (Japanese Industrial Standards Committee, JIS search; in Japanese. Envelope names and sizes)
- JIS P 0138 Trimmed sizes of processed paper (Japanese Industrial Standards Committee, JIS search; in Japanese. Finished sizes of the A and B series)
- ISO 216:2007 Writing paper and certain classes of printed matter. Trimmed sizes. A and B series (ISO)