Photo print sizes: 6x4, 7x5, 8x10 and the pixels needed

Inches, centimetres and shapes

VistaPrint Australia's photo guide gives the metric equivalents printers use: 6 by 4 inches is 10 by 15 centimetres, 5 by 7 is 13 by 18, 6 by 8 is 15 by 20, 8 by 10 is 20 by 25 and 8 by 12 is 20 by 30. These are rounded, not exact conversions, which matters only when a frame is tight. The more important number is the shape. A 6 by 4 and an 8 by 12 are both 3 to 2, the shape of most interchangeable lens cameras, so those photos fill the print. An 8 by 10 is 5 to 4, much squarer, and a 3 to 2 photo loses about a sixth of its length to fit.

Phone photos and the 4 to 3 problem

Most phone cameras shoot 4 to 3 by default, which matches an 8 by 6 print exactly and is close to 7 by 5. On a 6 by 4 print, a 4 to 3 photo loses a strip off the top or bottom, so heads near the edge of the frame get cut. Before ordering, crop each photo to the print's shape yourself rather than leaving it to the lab's automatic centre crop, or choose a print size that matches the camera. The image cropper and aspect ratio calculator do that crop with exact pixel counts.

How many pixels a print really needs

Labs quote 300 DPI as the target for prints held in the hand, which gives the pixel counts in the table. Lower densities still look fine on larger prints viewed from further away: at 150 DPI a 20 by 16 print needs only 3000 by 2400 pixels. A 12 megapixel phone photo, about 4000 by 3000 pixels, covers an 8 by 10 at more than 300 DPI and an 11 by 14 at around 280. The weak point is digital zoom and heavy cropping, which throw away pixels before the print is made.

Common mistakes

The first is ordering 8 by 10 prints of 3 to 2 photos and being surprised by the crop. The second is printing from a screenshot or a messaging app copy, which is often compressed to a fraction of the original pixels. The third is choosing gloss for prints that will go behind glass, which doubles the reflections. The fourth is a frame bought in centimetres for a print sized in inches, which leaves a few millimetres of gap or overlap.

Photos in the flyer editor

The flyer editor does not print photos and has no photo print canvas; its sizes are A4 portrait and landscape and six social formats. Photos come into a flyer through an image slot, where an upload of up to 10 megabytes is centre cropped to the slot's shape and cannot be repositioned, so it is worth cropping the photo to the slot's proportion first. For prints themselves, the image resizer and image cropper prepare exact pixel sizes for any lab, and the blank PNG above is 1800 by 1200 pixels, a 6 by 4 inch print at 300 DPI.

Questions people ask