Calculate maximum width and height
Divide image width and height in pixels by the target PPI. A 6000 × 4000 pixel image at 300 PPI produces a 20 × 13.33 inch print before cropping. At 200 PPI, the same file reaches 30 × 20 inches.
Calculate both dimensions. If your target paper has a different aspect ratio, cropping will remove pixels from one side and may reduce the maximum size.
| Image dimensions | At 300 PPI | At 240 PPI | At 150 PPI |
|---|---|---|---|
| 1200 × 1800 px | 4 × 6 in | 5 × 7.5 in | 8 × 12 in |
| 2400 × 3000 px | 8 × 10 in | 10 × 12.5 in | 16 × 20 in |
| 3600 × 5400 px | 12 × 18 in | 15 × 22.5 in | 24 × 36 in |
| 4000 × 6000 px | 13.33 × 20 in | 16.67 × 25 in | 26.67 × 40 in |
Account for crop before judging resolution
A camera image with a 3:2 ratio does not fill an 8 × 10 inch frame, which uses a 4:5 ratio. Filling the paper requires trimming the long dimension. The pixels outside the crop cannot contribute to print resolution.
Set the final crop first, then calculate with the cropped pixel dimensions. If important content reaches the edges, also consider whether bleed will require a slightly larger image area.
Match resolution to viewing distance
A hand-held print invites close inspection. A poster on a wall is normally viewed from farther away. As viewing distance increases, individual pixels become less visible, so a lower effective PPI can still look appropriate.
There is no single maximum size that applies to every image. Fine texture, sharp text and high-contrast edges reveal limitations more readily than soft or abstract subjects. Test a representative crop at final size when the job is important.
- Use a higher target for books, portfolios and close-viewed photographs.
- A moderate target may suit framed wall art and medium posters.
- Large displays should be assessed at their expected viewing distance.
- Always follow a production provider’s minimum specification.
What upscaling can and cannot do
Upscaling creates additional pixels by estimating values between existing pixels. Modern methods can make enlargement cleaner, but they do not recover authentic detail that the source never contained.
Start with the original file, avoid repeated resizing and apply sharpening for the final output size. If the source is already blurred, compressed or out of focus, adding pixels will not solve the underlying problem.