Postcard size
for print and mail.

The standard US postcard is 4 × 6 in (1800 × 1200 px at 300 DPI); USPS cards must be at least 3.5 × 5 in, and in Europe A6, 105 × 148 mm, is a common postcard size.

Design this size

Updated November 2026

All sizes at a glance

A postcard is a print job and a piece of mail, so its size has to suit both your printer and the post office.

Sizes and aspect ratios
Use	Size	Ratio	Note
US standard, 4 × 6 in (recommended)	6 × 4 in	3:2
USPS card minimum	5 × 3.5 in	10:7	At least 3.5 in high, 5 in long and 0.007 in thick
USPS stamped card maximum	6 × 4.25 in	24:17	Stamped cards and double cards, at most 0.016 in thick
USPS postcard maximum	9 × 6 in	3:2	DMM 201 limit for each postcard claimed at a card price
A6 (Europe)	148 × 105 mm	1.414:1 (√2)

Pixels at each resolution

The same physical size needs more pixels the sharper you want it. 300 DPI is the usual target for print, 150 DPI for large posters seen from afar.

Pixel size at 72, 96, 150 and 300 DPI
Resolution	Pixels	Good for
72 DPI	432 × 288 px	Screen previews
96 DPI	576 × 384 px	Web and office documents
150 DPI	900 × 600 px	Posters and large prints
300 DPI	1800 × 1200 px	Print at full quality

Physical size

Size in millimetres, centimetres and inches
Physical size	Size
Millimetres	152.4 × 101.6 mm
Centimetres	15.24 × 10.16 cm
Inches	6 × 4 in

Limits and safe zone

Thickness (USPS): 0.007 to 0.016 in; cards larger than 4.25 × 6 in must be at least 0.009 in
Shape (USPS): Rectangular, length 1.3 to 2.5 times the height, corners rounded up to 1/8 in
Bleed: Usually 0.125 in or 3 mm on each side; check your printer’s template

Semurai Canvas

Design it in Semurai Canvas

Set the postcard size in pixels, add your logo, colours and fonts from the Brand Kit, and let the AI chat adjust the layout when you ask. Export PNG or PDF and check your printer’s bleed and colour requirements.

Create a design, open Resize, choose “Resize this design” and set 1800 × 1200 px (any size from 200 to 6000 px).

Start free

After sign-up and a short brand setup, Canvas opens a blank 1800 × 1200 px design.

Already have an account? Open Canvas at 1800 × 1200 px

Standard postcard size and USPS limits

The standard US postcard, 4 × 6 in, fits both USPS card limits: at least 3.5 × 5 in, and at most 4.25 × 6 in for stamped cards (Domestic Mail Manual 201).

For commercial mailings, DMM 201 allows each postcard up to 6 × 9 in. Check the current USPS rules and prices for your mailing before you print a card larger than 4.25 × 6 in.

Shape, thickness and corners

USPS wants a rectangle whose length is 1.3 to 2.5 times its height. A 4 × 6 in card has a ratio of 1.5, well inside that range.

Cards must be 0.007 to 0.016 in thick, and cards over 4.25 × 6 in at least 0.009 in. Corners may be rounded up to 1/8 in.

Postcard size in Europe

A6 is a common postcard size in Europe: 105 × 148 mm, or 1748 × 1240 px at 300 DPI in landscape.

A6 is close to 4 × 6 in (about 102 × 152 mm) but not the same shape, so a US design needs a small re-layout for a European printer.

Tips

Set 1800 × 1200 px for a landscape 4 × 6 in card at 300 DPI, or 1200 × 1800 px for portrait.
Keep the address side simple: it needs room for the address and postage.
Run the background 0.125 in past the edge for bleed and keep text the same distance inside the trim.
Ask your printer for the card thickness: USPS accepts 0.007 to 0.016 in.

How to make it in Semurai Canvas

Create a design in Semurai Canvas, open More → Resize…, choose “Resize this design” and enter 1800 × 1200 px (6 × 4 in at 300 DPI).
Add your photo, headline and logo, or ask the AI chat to lay out the front for you.
Export a PNG or PDF, then check your printer’s bleed and colour requirements before you order.

The Resize window in Semurai Canvas with preset sizes and a custom width and height

FAQ

Questions about this size

What size is a standard postcard?

4 × 6 in in the US, which is 1800 × 1200 px at 300 DPI. In Europe A6, 105 × 148 mm, is a common size.

What is the largest postcard size USPS accepts?

DMM 201 allows 4.25 × 6 in for stamped cards and up to 6 × 9 in for each postcard in commercial mailings. Check the current USPS rules and prices before you print anything larger than 4 × 6 in.

What is the smallest postcard you can mail?

USPS cards must be at least 3.5 × 5 in and 0.007 in thick. Smaller pieces do not meet the USPS card standards.

Can I print an A6 postcard for the US?

Yes, A6 (105 × 148 mm, about 4.1 × 5.8 in) is inside the USPS card limits. It is a slightly different shape from 4 × 6 in, so check the layout before you print.