Choose the size for the job
Compare this size with 16 × 24 if you want the same framing at a different scale. Both preserve a 3:2 image. Before enlarging, inspect the source for motion blur or heavy compression: a sufficient pixel count does not repair those defects.
| Measurement | Value |
|---|---|
| Inches | 12 × 18 |
| Centimetres | 30.48 × 45.72 |
| Millimetres | 304.8 × 457.2 |
| Short-edge-to-long-edge ratio | 2:3 |
Pixel examples
These examples multiply each edge in inches by the stated PPI. They describe pixel counts for the chosen size, not a universal pass or fail rule for appearance. Use the retained pixels after cropping when checking an existing photo.
| Example PPI | Pixels |
|---|---|
| 150 | 1,800 × 2,700 |
| 240 | 2,880 × 4,320 |
| 300 | 3,600 × 5,400 |
A worked example
A 6000 × 4000 landscape image printed at 18 × 12 inches provides 333⅓ PPI. No pixels need to be cropped when the aspect ratio already matches. A 3600 × 2400 version of that image would provide 200 PPI at the same size; changing its resolution metadata would not restore the missing samples.
Before you print
A3 is 297 × 420 mm, smaller than this print on both edges. A2 is 420 × 594 mm, leaving 57.6 mm at each side and 68.4 mm above and below a centred portrait 12 × 18 image. Those spaces can hold a border, but printer support for A2 must be checked separately.