Postcard Size Photo Maker

The 4 × 6 inch standard

Postcard size is the most widely printed photo format in the world, and the one price every lab quotes by default. In numbers it is 4 × 6 inches, 102 × 152 mm, 10.2 × 15.2 cm, and a 2:3 aspect ratio. That ratio is inherited from 35 mm film, which is why prints from an old camera fill the paper edge to edge while phone photos never quite do. Portrait and landscape use the same sheet — only the orientation of the crop changes.

What postcard prints are used for

• Everyday photo lab prints for albums, envelopes and pinboards
• Standard 4 × 6 frames sold in every stationery and home shop
• Actual postcards, greeting cards and invitations
• Forms and portfolios that ask for a "postcard size photograph" rather than a passport one
• Sheets of smaller photos, which are printed on the same 4 × 6 paper and then cut

The DPI you need for a sharp print

DPI describes how many pixels get packed into each printed inch, so the target resolution follows directly from the paper size. At 300 DPI — the quality standard for photographic printing — 4 × 6 inches needs 1200 × 1800 pixels. At 200 DPI you would only need 800 × 1200, and the result is usually acceptable at arm's length but visibly soft close up. Below about 150 DPI the individual pixels start to show as blur along hair and edges.

Almost any modern phone clears 1200 × 1800 comfortably; a 12-megapixel camera produces around 3000 × 4000 pixels. The problem is rarely the camera and almost always the copy. Screenshots, WhatsApp forwards and images saved from social media have already been resized down, and no tool can restore detail that was thrown away. Start from the original file in your gallery whenever you still have it, and avoid zooming so far into the crop that you fall below the pixel budget.

Getting the print you expect

Drag and zoom the image inside the frame before downloading, because a lab's automatic crop centres the photo and regularly cuts off the top of someone's head. When you hand over the file, ask for actual size rather than fit-to-page. Need a different format instead? Compare every option on the passport photo dimensions reference table, make the small 20 × 25 mm version with the stamp size photo maker, or return to the free passport size photo maker for a 35 × 45 mm crop and a printable sheet.