Journal · 4 min read
Postcard size: the 4 x 6 standard and USPS dimensions
What is the standard postcard size?
The standard postcard size in the US is 4 x 6 inches. To mail with a 65¢ postcard stamp, a card must be rectangular, 3.5 to 4.25 inches tall, 5 to 6 inches long and 0.007 to 0.016 inch thick (USPS, checked October 13, 2026).
What size is a postcard?
The standard postcard size in the US is 4 x 6 inches (102 x 152 mm), the same as a standard photo print.
USPS treats anything from 3.5 x 5 up to 4.25 x 6 inches as a postcard, mailed with one postcard stamp.
| Size | Inches | mm | Pixels at 300 dpi | Postcard stamp? |
|---|---|---|---|---|
| Smallest USPS postcard | 3.5 x 5 | 89 x 127 | 1050 x 1500 | Yes |
| Standard | 4 x 6 | 102 x 152 | 1200 x 1800 | Yes |
| Largest USPS postcard | 4.25 x 6 | 108 x 152 | 1275 x 1800 | Yes |
| A6 (Europe, UK) | 4.1 x 5.8 | 105 x 148 | 1240 x 1748 | Yes |
| 5 x 7 | 5 x 7 | 127 x 178 | 1500 x 2100 | No, letter price |
| A5 | 5.8 x 8.3 | 148 x 210 | 1748 x 2480 | No, letter price |
| 6 x 9 | 6 x 9 | 152 x 229 | 1800 x 2700 | No, letter price |
| 6 x 11 | 6 x 11 | 152 x 279 | 1800 x 3300 | No, letter price |
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The A5 and A6 sizes come from the ISO 216 paper standard, as listed in the ISO 216 reference kept by the University of Cambridge.
USPS postcard size: minimum and maximum dimensions
USPS sets the card price limits in section 6.2.2 of its Domestic Mail Manual. A card has to pass every row, not just one.
| Minimum | Maximum | |
|---|---|---|
| Height | 3.5 in | 4.25 in |
| Length | 5 in | 6 in |
| Thickness | 0.007 in | 0.016 in |
| Weight | None set | 3.5 oz |
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It must also be a rectangle of even card stock, with no folds or creases. Miss any rule and it pays the letter price.
Weight rarely matters for a single card. Past 3.5 ounces, though, USPS charges the flat price, the rate for large envelopes.
Source: USPS Domestic Mail Manual 101, sections 1.1 and 6.2, read October 13, 2026.
Mailing cards in bulk for a business? USPS Business Mail 101 covers card rules for presorted mail, which we don't handle.
Can you mail a 5 x 7 as a postcard?
No. At 5 inches tall it is over the 4.25 inch limit, so USPS charges it as a letter: one Forever stamp, 82¢.
A5, 6 x 9 and 6 x 11 cards are letters too.
Each fits inside the letter maximum of 6.125 x 11.5 inches, so one Forever stamp covers it up to 1 ounce.
Square cards cost more again: USPS adds 49¢ to anything its sorting machines can't handle.
The postcard postage calculator works out the stamps for any size and any number of cards.
Free printable 4 x 6 postcard template
The template is a free PDF with two 4 x 6 postcard fronts and two backs on US Letter paper. No sign-up, no email.
- A stamp box in the top right corner of each back.
- Address lines inside the USPS read area: 1/2 inch in from each side, 5/8 to 2 3/4 inches up from the bottom.
- The bottom 5/8 inch marked "leave blank", where USPS prints its barcode.
- A 1 inch scale bar, so you can check the print with a ruler.
Print at "Actual size" or 100%. "Fit to page" shrinks the cards. Then cut on the crop marks.
For two-sided cards on card stock, print page 2 on the back of page 1 with long-edge flip.
Download the 4 x 6 postcard template (PDF, US Letter, 2 pages).
For a print shop, use the print-ready template with bleed: 6.25 x 4.25 inches per side, 0.125 inch bleed and safe line.
That bleed file is the exact spec FamilyLetter prints its own cards to.
In Google Docs, Word or Canva? Insert the postcard back template PNG (1875 x 1275 pixels, 300 dpi) as a page background.
In the bleed PDF and PNG: run your background to the tinted edge, the solid line is the cut, keep words inside the dashes.
Vertical and square postcards
A vertical postcard is fine. USPS measures length along the address lines, so write the address across the long side of the card.
The diagrams are in how to address a postcard.
Square cards are the exception covered above: they mail as letters, with the surcharge on top.
Skip the size question
Or skip all of it. FamilyLetter prints your photos on a real 4 x 6 card, adds the postage and mails it.
Up to four photos go on glossy card stock. No app, no account, and you see the finished front and back before you pay.
Start from your camera roll with 4 x 6 photo postcards, each mailed to the US address you give us.
Not ready to order? Design a postcard online and look at the real card first. Nothing prints until you check out.
It is also how to send a postcard without a stamp or a trip to the post office.
We're the wrong fit for other sizes, addresses outside the US, or bulk marketing mail. For those, look at postcard apps that print other sizes.
Frequently asked questions
- Are most postcards 4 x 6 or 5 x 7?
- Most are 4 x 6. A 5 x 7 is a common greeting card and photo size, but it is too tall for the postcard price, so it mails as a letter with a Forever stamp (82¢).
- Is A6 a postcard size?
- Yes. A6 is 105 x 148 mm, about 4.1 x 5.8 inches, and it is the usual postcard size in Europe and the UK. It fits the USPS limits, so it mails from the US with a postcard stamp.
- How thick does a postcard have to be?
- Between 0.007 and 0.016 inch, and the same thickness all over, according to USPS. A thicker card loses the postcard price and pays the letter price.
- Do postcards need an envelope?
- No. A postcard travels bare, with the stamp and address on the back. Put it in an envelope and it becomes a letter, which takes a Forever stamp (82¢).
- Is it cheaper to mail a postcard than a letter?
- Yes. USPS charges 65¢ for a postcard stamp and 82¢ for a Forever stamp, the price of a 1 ounce letter. Prices as of October 9, 2026.
- What size is a postcard in pixels?
- At 300 dpi, the usual print resolution, a 4 x 6 postcard is 1200 x 1800 pixels. With a 0.125 inch bleed on every side for a print shop, it is 1275 x 1875.
