Envelopes and mailPS-06
What Size Is a Japanese Postcard in cm? Pixels, Aspect Ratio, Japan Post Rules and Making Your Own
Postcard size is set by two things: the paper dimensions and the postal standard. The dimensions and pixel counts come first in a table, followed by the rules for private postcards and how to make print data.
In this article (15 sections)
- Conclusion: what is the postcard size in cm, and how many pixels?
- How do you get the postcard size with the calculator tool?
How is postcard size different from A6 and L-size?1
How does Japan Post define postcard size?2
- What happens in the mail if a card is bigger than postcard size?
What are the size and rules for private postcards?2
How do you make print data at postcard size?2
How do you make postcard-size cards from A4?1
- What size envelope fits a postcard?
- How do overseas postcards differ from Japanese postcard size?
- What are common mistakes with postcard size?
- What terms come up with postcard size?
What else is worth knowing along with postcard size?3
- Sources
Postcard size is a postal standard set by Japan Post. The regular postcards that Japan Post issues come in one fixed size.
Private postcards (shisei hagaki) that you make yourself have an allowed range of size and weight. Outside that range, the item is treated as a letter, not a postcard.
When you make print data, cm alone is not enough. You also need to decide the pixel count and the bleed.
Here is the key point. Check postcard size in two ways: the paper dimensions and the postal standard.
This article covers the following.
- Postcard dimensions (mm, cm, inches) and pixel counts by dpi
- How it differs from A6 and L-size, and its aspect ratio
- Standards and weights for regular postcards, return postcards and private postcards
- How postcards differ from standard-size mail, and the postage categories
- Rules for private postcards, such as the "postcard" (Yubin Hagaki) marking
- How to make print data that includes bleed
- Imposition when making postcards from A4
- How Japanese postcards differ from postcards in other countries
The dimensions are shown in tables based on Japan Post's Domestic Mail Terms and Conditions.
Conclusion: what is the postcard size in cm, and how many pixels?
The postcard size is shown in the table below. These are the dimensions of the regular postcard issued by Japan Post.
| Size | Japanese postcard |
|---|---|
| Series | Japan Post |
| mm (w × h) | 100 × 148 |
| cm | 10 × 14.8 |
| inches | 3.94 × 5.83 |
| px (72 dpi) | 283 × 420 |
| px (150 dpi) | 591 × 874 |
| px (300 dpi) | 1181 × 1748 |
| px (350 dpi) | 1378 × 2039 |
| Typical use | Standard postcard |
Source: Japan Post domestic postal terms, Art. 21
The px values in the table are "width × height" in portrait orientation. If you use the card in landscape, swap the width and height.
Choose the pixel count by how you will use it.
- Screen only (social media, email): the 72dpi or 150dpi values are enough
- Printing photos on a home printer: 200 to 300dpi is a good guide
- Sending to a print shop: use 300dpi as the base, or 350dpi if they ask for it
If in doubt, make it at the 300dpi values. You can scale it down for screens later.
A postcard you make yourself can still be mailed as a postcard if it is slightly different from these dimensions, as long as it is within the allowed range. The range is given in the section on Japan Post's standards below.
How do you get the postcard size with the calculator tool?
To get the postcard size, choose "postcard" as the paper in the tool above. When you change the dpi, the pixel count changes too.
The tool also gives values not in the table, such as 200dpi or 600dpi, using the same formula. The tool runs only in your browser and does not send the values you enter.
The formula is the same as for A4. See A4 size in pixels for details.
- Width: 100 ÷ 25.4 × 300 = 1181.1 → 1181px
- Height: 148 ÷ 25.4 × 300 = 1748.0 → 1748px
How is postcard size different from A6 and L-size?
| Size | mm (w × h) | inches | px (300 dpi) |
|---|---|---|---|
| A6 | 105 × 148 | 4.13 × 5.83 | 1240 × 1748 |
| Japanese postcard | 100 × 148 | 3.94 × 5.83 | 1181 × 1748 |
| L (photo) | 89 × 127 | 3.5 × 5 | 1051 × 1500 |
Source: JIS P 0138, ISO 216, ANSI/ASME Y14.1 / Japan Post domestic postal terms, Art. 21 / Fujifilm, multifunction printer photo prints (L and 2L are customary, not formal standards)
As the table shows, a postcard and A6 have the same height and differ only in width. A6 is 5mm wider.
A6 is a paper size defined by ISO 216 and JIS P 0138. The postcard size is a postal standard, so the two come from different sources.
If you print data set up for A6 on a postcard, one edge gets slightly cut off. Choose "postcard" as the paper size in both your software and your printer settings.
L-size is a photo print size, a little smaller than a postcard. See L-size for details.
What is the aspect ratio of a postcard?
The aspect ratio of a postcard is about 1.48 on the long side for 1 on the short side. 148 ÷ 100 = 1.48, which in whole numbers is 25 : 37.
A-series paper is 1 : √2 (about 1.414). A postcard is a little taller and narrower than A-series paper.
A 3:2 camera photo fits on a postcard almost as is. The table below shows how much is cropped for each ratio.
| Photo ratio | When placed to fill the postcard | Share cropped (calculated) |
|---|---|---|
| 3:2 | Height is 2mm over, almost nothing cropped | About 1% |
| 4:3 | Width is about 11mm over | About 10% |
| 16:9 | Height is about 30mm over | About 17% |
| 1:1 (square) | Width is 48mm over | About 32% |
The calculation matches the short side of the photo to the postcard width. Only 4:3 is matched to the height instead.
When a large share is cropped, you can add white margins instead. Decide by whether the main subject of the photo would be cut off.
How does Japan Post define postcard size?
Postcard size is set by Articles 21 and 22 of Japan Post's Domestic Mail Terms and Conditions. The rules differ for postcards issued by Japan Post and postcards you make yourself.
| Type | Size | Weight | Basis |
|---|---|---|---|
| Regular postcard (issued by Japan Post) | The dimensions in the conclusion table | Fixed paper | Terms, Article 21 |
| Return postcard (issued by Japan Post) | Outgoing and reply parts are each the same as a regular postcard, joined along their long sides | Fixed paper | Terms, Article 21 |
| Private regular postcard | Rectangle, long side 14 to 15.4cm, short side 9 to 10.7cm | 2 to 6g | Terms, Article 22 |
| Private return postcard | Unfolded: long side 18 to 21.4cm, short side 14 to 15.4cm | 4 to 12g (2 to 6g per half) | Terms, Article 22 |
A private postcard counts as a postcard only when both its size and its weight are within range. Japan Post's guidance also says that items outside the standard are handled as first-class mail (daiisshu yubinbutsu, i.e. letters).
The range for private postcards assumes a rectangle. Square or round cards do not qualify as postcards.
What size is a return postcard?
A return postcard (ofuku hagaki, a postcard with an attached reply card) is paper the size of two regular postcards, folded in the middle. Unfolded, the short sides of two postcards sit side by side.
The unfolded width is 100 × 2 = 200mm. The height is the same as the long side of a postcard.
Japan Post's guidance says to fold it so that the fold is on the right. The return postcards Japan Post sells are not folded in the middle, so you can print them as they are.
The reply part needs either a stamp for the reply postage or a business reply (postage paid by the addressee) marking. This is the rule for private return postcards (Terms, Article 22).
Is a New Year's postcard the same size as a regular postcard?
Yes. A New Year's postcard (nenga hagaki) is the same size as a regular postcard.
A New Year's postcard is a postal postcard with a lottery number.
The types of New Year's postcards for 2026 included the following.
- Plain: the most basic type
- Plain (inkjet paper): for home inkjet printers
- Plain (inkjet photo): only for dye-based inkjet printers
- Plain (four-up sheet): four postcards printed in a 2 × 2 grid, for printing in bulk
Four-up sheets must be cut into four cards before mailing. If they are not cut apart, they are not accepted as postcards.
What happens in the mail if a card is bigger than postcard size?
A card bigger than postcard size is handled as first-class mail (a letter). If it is within the size range for standard-size mail (teikei), it goes as standard-size mail; if larger, it goes as non-standard-size mail (teikeigai).
In Japan Post's rate table, postcards and letters are divided as follows.
| Category | Size | Weight | Rate category |
|---|---|---|---|
| Regular postcard | Within the standard above | 2 to 6g | One flat nationwide rate |
| Return postcard | Within the standard above | 4 to 12g | One flat nationwide rate |
| Standard-size mail | Length 14 to 23.5cm, width 9 to 12cm, thickness up to 1cm | Up to 50g | One weight band |
| Non-standard-size (within limits) | Long side 34cm, short side 25cm, thickness 3cm or less | 1kg or less | Six weight bands |
| Non-standard-size (over limits) | Long side 60cm or less, three sides totaling 90cm or less | 4kg or less | Eight weight bands |
Postage amounts may be revised. Check Japan Post's rate table (letters and postcards) before you mail.
Even a card bigger than a postcard can go at the standard-size letter rate if it fits within the standard-size mail range.
A card can be handled as a letter even when its size is within range. This happens when it breaks the rules on how the address side is written or on attaching things to it (Terms, Article 25).
What are the size and rules for private postcards?
You can make your own private postcards if they meet the rules on size, weight, paper and markings. The rules are in Article 22 of the Terms and in Japan Post's Q&A.
| Rule | Details | Source |
|---|---|---|
| Size | Rectangle, long side 14 to 15.4cm, short side 9 to 10.7cm | Terms, Article 22 |
| Weight | 2 to 6g | Terms, Article 22 |
| Paper and thickness | Equal to or better than postcards issued by Japan Post | Terms, Article 22 |
| Address side color | White or a light color | Terms, Article 22 |
| Marking | "Yubin Hagaki" (postcard) or equivalent wording | Terms, Article 22 |
| English marking | "POSTCARD" is acceptable | Japan Post Q&A |
| Postal code boxes | Not required. If printed, use vermilion or gold-red | Japan Post Q&A |
| Message on the address side | Only in the lower half (left half if landscape) | Terms, Article 23 |
| Attachments | Only thin paper stuck down over its whole surface | Terms, Article 24 |
The rule most often forgotten is the "Yubin Hagaki" (postcard) marking. Japan Post's Q&A says a card without it is handled as a letter.
Where do you put the "Yubin Hagaki" (postcard) marking?
Put the "Yubin Hagaki" marking clearly at the top of the address side or in the middle of its left edge. When the card is used in landscape, put it in the middle of the right edge.
On a return postcard, put "Yubin Ofuku Hagaki" (return postcard) on both the outgoing part and the reply part.
If you write it in English, write "POSTCARD". Japan Post's Q&A lists it as equivalent wording.
How thick does the paper for a private postcard need to be?
The paper for a private postcard must be thick enough for one card to weigh at least 2g. Calculated from the area of a postcard, that is a grammage (weight per m²) of about 135g/m² or more.
The area of a postcard is 0.1 × 0.148 = 0.0148m². 2 ÷ 0.0148 ≈ 135, and 6 ÷ 0.0148 ≈ 405.
| Grammage (g/m²) | Common paper | Weight of one postcard (calculated) | Within 2 to 6g? |
|---|---|---|---|
| 67 | Ordinary copy paper | About 0.99g | No |
| 104.7 | Woodfree paper, 90kg ream weight | About 1.55g | No |
| 127.9 | Woodfree paper, 110kg ream weight | About 1.89g | Slightly short |
| 157 | Woodfree paper, 135kg ream weight | About 2.32g | Yes |
| 209.3 | Woodfree paper, 180kg ream weight | About 3.10g | Yes |
| 256 | Woodfree paper, 220kg ream weight | About 3.79g | Yes |
Copy paper cut to size does not make a postcard. Japan Post's guidance also says that thin cards under 2g should be stuck over their whole surface onto a backing card before mailing.
The weights are a guide. The Terms also require the "paper quality and thickness" to be equal to or better than Japan Post's postcards.
How do you make print data at postcard size?
Make postcard print data at the finished size plus bleed. The standard resolution is 300dpi.
Bleed is the extra area you extend outward when color or photos run to the edge of the paper. It prevents white edges caused by slight shifts in trimming (the step where the paper is cut).
Follow the bleed width your print shop (the place you send the data to) specifies. In Japanese printing, 3mm is the widely used setting.
Before you order printing, check the bleed width in the print shop's guide. If the width is wrong, you may have to remake the data.
How many pixels with bleed?
With 3mm of bleed, it is 1252 × 1819px at 300dpi. Add 3mm twice (both sides) to each dimension, then use the same formula.
- Width: (100 + 3 × 2) ÷ 25.4 × 300 = 1252.0 → 1252px
- Height: (148 + 3 × 2) ÷ 25.4 × 300 = 1818.9 → 1819px
- At 350dpi: 1461 × 2122px
Keep text and important artwork inside the trim line, away from it. Set that distance to match your print shop's spec too.
Some home printers cannot print borderless. Check the "print area" section of your printer's manual to see whether it can print borderless.
How much of the address side can have pictures or text?
You can write a message on the address side only in the lower half (left half if landscape). This is the rule in Article 23 of the Terms.
However, this does not apply if the message is clearly distinguishable from the address and postal code.
Japan Post's guidelines recommend avoiding dark or fluorescent background colors on the address side, so machines can read the address.
It is safest to put photos and pictures on the back (the message side). Keep the address side white or a light color.
How do you make postcard-size cards from A4?
One sheet of A4 fits four postcards, two across and two down. However, there is no room for bleed.
| Size | mm (w × h) |
|---|---|
| A4 | 210 × 297 |
| A5 | 148 × 210 |
| B5 | 182 × 257 |
| Japanese postcard | 100 × 148 |
Source: JIS P 0138, ISO 216, ANSI/ASME Y14.1 / Japan Post domestic postal terms, Art. 21
Using the dimensions in the table, imposition (how many cards fit on one sheet) works out as follows.
| Source sheet | Postcards per sheet | Leftover (calculated) |
|---|---|---|
| A4 | 4 (2 across, 2 down) | Width 10mm, height 1mm |
| A5 | 2 (postcards in landscape, 2 rows) | Width 0mm, height 10mm |
| B5 | 2 (postcards in landscape, 2 rows) | Width 34mm, height 57mm |
| A6 | 1 | Width 5mm, height 0mm |
The A4 calculation is as follows.
- Width: 100 × 2 = 200 (within the A4 width)
- Height: 148 × 2 = 296 (within the A4 height)
With four cards on A4 there is almost no gap, so there is no room for bleed. If your design runs color to the edges, printing one card at a time on postcard stock gives a cleaner result.
Many home printers cannot print to the very edge of A4. When making cards from A4, use a design with white margins around it.
After printing four up on A4, cut them apart with a ruler and a utility knife. If you add crop marks (tombo) to the data, you will know exactly where to cut.
What is the zoom ratio for enlarging postcard size to A4?
To enlarge a postcard to A4, the zoom ratio is 200%. Work out the ratio for the width and the height, and use the smaller one.
- Width: 210 ÷ 100 = 2.1
- Height: 297 ÷ 148 ≈ 2.01
To reduce A4 to postcard size, it is 47%. 100 ÷ 210 ≈ 0.476 is the largest that fits.
Because the aspect ratios differ, scaling between A4 and a postcard leaves a little margin either way. You can get the zoom ratio for other paper sizes with the calculator tool above.
To see all paper standards together, use the list of paper sizes.
What size envelope fits a postcard?
To put a postcard in an envelope, a Yogata No. 2 (Western-style No. 2) envelope fits it just right. It is also within the standard-size mail range.
| Envelope | mm (w × h) | Fits | Japan Post class (≤1 cm thick, ≤50 g) |
|---|---|---|---|
| Nagagata No. 3 | 120 × 235 | A4 folded in three | Standard (teikei) |
| Kakugata No. 2 | 240 × 332 | A4 flat | Non-standard (within size) |
| Yogata No. 2 | 162 × 114 | Postcard, A4 folded in four | Standard (teikei) |
Source: JIS S 5502, Japan Post mail size classes
As the table shows, a Yogata No. 2 envelope holds a postcard without folding it. It also holds an A4 sheet folded into quarters.
Yogata No. 2 is also handy when you enclose a reply postcard with an invitation or announcement. A Nagagata No. 3 envelope also fits, but leaves a lot of space around the postcard.
A postcard in an envelope cannot go at the postcard rate. It goes at the letter rate, based on the weight of the whole envelope.
How do overseas postcards differ from Japanese postcard size?
Postcard rules for overseas postcards differ by country. The Japanese postcard size also fits within Japan's international mail range and the US standard.
| Standard | Size accepted as a postcard | Source |
|---|---|---|
| Japanese private postcard (domestic) | Long side 14 to 15.4cm, short side 9 to 10.7cm | Domestic Mail Terms, Article 22 |
| Postcard from Japan to other countries | Long side 14 to 23.5cm, short side 9 to 12cm, long side at least 1.4 times the short side | Japan Post international mail guide |
| US postcard (postcard rate) | Height 3.5 to 4.25 inches, length 5 to 6 inches, thickness 0.007 to 0.016 inches | USPS Domestic Mail Manual 101 6.2.2 |
The US maximum of 4.25 inches is about 108mm, from 4.25 × 25.4 = 107.95. A card at the full US maximum exceeds the upper limit for the short side of a Japanese private postcard.
Suppose you mail a large postcard bought abroad to an address in Japan. If it is outside the range, it is handled as a letter, not a postcard.
Measure postcards bought on a trip with a ruler before you mail them. If they are outside the range, the letter rate applies.
When mailing from Japan to other countries, the size range for postcards is wider than for domestic mail. Check the postage in Japan Post's international mail guide.
For how US office paper differs from A4, see Letter size vs A4.
What are common mistakes with postcard size?
The most common mistake is printing on a postcard with the A6 setting still on. The mistakes people ask about most are in the table below.
| Mistake | What happens | How to fix it |
|---|---|---|
| Making data at A6 and printing on a postcard | The width is 5mm off and an edge gets cut | Set the paper size to "postcard" |
| Running color to the edge without bleed | Trimming shifts leave white edges | Add bleed at the width your print shop specifies |
| No "Yubin Hagaki" marking on a private postcard | Handled as a letter | Put it at the top or on the left of the address side |
| Cutting copy paper to make postcards | Under 2g, so not a postcard | Use thick paper of 135g/m² or more |
| Writing a message on the upper half of the address side | May be handled as a letter | Keep it in the lower half (left half if landscape) |
| Mailing a four-up sheet without cutting it | Not accepted as postcards | Cut it into four cards |
| Using inkjet photo cards in another type of printer | They are only for dye-based inkjet printers, so they do not match | For pigment inkjet or laser, choose plain or inkjet paper cards |
| Placing a 4:3 photo as is | About 10% of the width is cropped | Check that the main subject is not cut off |
After making private postcards, weighing one card gives peace of mind. A scale that reads in 1g steps lets you check the 2g and 6g limits.
What terms come up with postcard size?
| Term | Meaning | Source |
|---|---|---|
| Regular postcard (tsujo hagaki) | A postcard sent as a single card. The formal name in the Terms | Domestic Mail Terms |
| Return postcard (ofuku hagaki) | A postcard with the outgoing and reply parts joined | Domestic Mail Terms |
| Private postcard (shisei hagaki) | A postcard made by anyone other than Japan Post | Domestic Mail Terms, Article 22 |
| Second-class mail (dainishu yubinbutsu) | Postal postcards | Domestic Mail Terms, Article 20 |
| First-class mail (daiisshu yubinbutsu) | Letters (sealed mail etc.). Divided into standard-size and non-standard-size | Japan Post rate table |
| Printed stamp (ryogaku inmen) | The stamp printed on a postcard from the start | Domestic Mail Terms, Article 21 |
| Four-up sheet (yonmen rensatsu) | A sheet with four postcards printed in a 2 × 2 grid | Japan Post list of card types |
| Grammage | Weight of paper per m² (g/m²) | JIS P 8124 |
| Bleed | Artwork extended outside the finished size | Print shop specs |
| Imposition | The layout of how many pieces go on one sheet | General printing term |
What else is worth knowing along with postcard size?
Is the "postcard size" at photo shops the same as a postal postcard?
Not necessarily. Photo prints come in a size called "postcard size", but check the dimensions in the shop's guide.
If you are mailing it, check that it is within the postal postcard range. Even when printed on photo paper, it can be mailed as a private postcard if it meets the size and weight rules.
What if you want to make a large poster or notice?
For anything bigger than a postcard, choose from the paper standards. Whether you pick the A series or the B series changes how it looks.
Decide the size of a notice by how far away people will view it. How to choose is covered in Poster sizes.
Where do the numbers on this site come from?
The dimensions on this site come from a single dataset based on ISO, JIS and Japan Post materials. The tables and the tools read the same data.
How we check the data and our editorial policy are in About this site.
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.
Paper sizesHow Many cm Is L-Size? Differences from 2L and Postcards, Aspect Ratio, Pixels and Printing Without CroppingL-size next to 2L-size and postcards in mm, inches and pixels, how much 4:3 and 16:9 phone photos lose, pixels needed, home and store printing, albums and frames.
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.What are common questions about postcard size?
What is the postcard size in cm?
See the cm row of the conclusion table. Those are the dimensions of the regular postcard issued by Japan Post.
A private postcard can be mailed if its long side is 14 to 15.4cm and its short side is 9 to 10.7cm.
Are a postcard and A6 the same size?
No. The height is the same, but A6 is 5mm wider.
When printing, set the paper size to "postcard".
How many pixels is a postcard?
It depends on the dpi. At 300dpi, the standard for printing, it is the px (300dpi) value in the conclusion table.
If you are sending it to a print shop, make it 1252 × 1819px (300dpi) with bleed added.
What size is a return postcard?
It is two regular postcards' worth of paper folded in the middle. Unfolded, it is twice as wide as a postcard.
For a private one, it is 18 to 21.4cm on the long side and 14 to 15.4cm on the short side, unfolded.
How heavy can a private postcard be?
From 2g to 6g. A return postcard is from 4g to 12g.
Copy paper is too light, so use thick paper.
How much is postage for a postcard?
It is one flat rate nationwide. The amount may be revised, so check Japan Post's rate table.
The domestic rate table (letters and postcards) lists the rates for regular postcards and return postcards.
Sources
- Second-class mail: postcards (Japan Post)
- Domestic rate table (letters and postcards) (Japan Post)
- Domestic Mail Terms and Conditions, Articles 20 to 25 (Japan Post)
- Guidelines for making standard-size mail and postcards (Japan Post)
- Basic conditions for standard-size mail and postcards (size and weight) (Japan Post)
- Dark-colored and fluorescent mail, pressure-sealed postcards (Japan Post)
- I heard private postcards must say "Yubin Hagaki". Can it be written in English? (Japan Post Q&A)
- Do postcards I make myself need postal code boxes? (Japan Post Q&A)
- Is there a set color for postal code boxes on private postcards and envelopes? (Japan Post Q&A)
- List of 2026 (Reiwa 8) New Year's postcard types (Japan Post)
- Types of regular postcards (Japan Post)
- Postcards (international mail) (Japan Post)
- Domestic Mail Manual 101 Physical Standards, 6.2.2 Postcard Dimensions (USPS)
- ISO 216:2007 Writing paper and certain classes of printed matter. Trimmed sizes. A and B series (ISO)
- JIS P 0138 Trimmed sizes of processed paper (Japanese Industrial Standards Committee, JIS search)
- Print lessons that change your photos, Lesson 3: pixel count and resolution (Canon)
