Guide · Updated 2026-10-08
Print Resolution and DPI Explained With Examples
How many pixels you need to print a photo or design at A4, A3 and other sizes, what effective DPI means, why bleed matters and why upscaling does not add detail.
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A picture that looks sharp on a screen can print blurry if it does not have enough pixels for the size you want. The key figure is effective DPI: the number of pixels per inch that will actually appear on the print.
The calculation
Effective DPI = the picture's pixel width ÷ the print width in inches. There are 25.4 mm in an inch. For 300 DPI, the pixels you need are the print size in inches multiplied by 300.
Pixels needed at 300 DPI
| Print size | Millimetres | Pixels at 300 DPI | Pixels at 150 DPI |
|---|---|---|---|
| A6 | 105 x 148 | 1,240 x 1,748 | 620 x 874 |
| A5 | 148 x 210 | 1,748 x 2,480 | 874 x 1,240 |
| A4 | 210 x 297 | 2,480 x 3,508 | 1,240 x 1,754 |
| A3 | 297 x 420 | 3,508 x 4,961 | 1,754 x 2,480 |
| 6 x 4 inch photo | 152 x 102 | 1,800 x 1,200 | 900 x 600 |
A worked example
A 3,000 x 2,000 pixel photo (6 megapixels) printed at A4 landscape (297 x 210 mm, or 11.7 x 8.3 inches) gives about 242 DPI. Add a 3 mm bleed on each side, so the printed area is 303 x 216 mm, and the effective DPI drops to about 235. That is good for most prints, although slightly below the ideal 300 DPI for close viewing. The Print-Ready Image Checker does this for batches of images.
What DPI is good enough?
- 300 DPI or more: sharp for close viewing, books, brochures and small prints.
- 200 to 300 DPI: good for most photos and posters seen at arm's length.
- 150 to 200 DPI: acceptable for large prints viewed from a distance.
- Below about 120 DPI: likely to look soft or pixelated up close.
Bleed and crop
If a design runs to the edge of the paper, printers ask for a bleed: extra image beyond the trim line, usually 3 mm, so that cutting never leaves a white edge. Add it to your size before checking DPI. If the picture's shape differs from the print shape, the print will crop some of it. A 3:2 photo on a 4:3 print loses about 11 percent of its width.
Why upscaling does not help
Enlarging an image in software makes more pixels, but it cannot add real detail, so it still looks soft. AI upscalers can produce a convincing result for some pictures, but check carefully before printing. Where possible, use the original, highest-resolution file from your camera rather than a compressed copy sent through a messaging app.
Preparing images for printing
Keep a full-size original for printing and use the Image Compressor or Image Resizer only for web copies. Save printing files as high-quality JPG or PNG, and check the printer's own guidance on colour profile and file type.
Frequently asked questions
Does DPI stored in the file matter? Not much. The pixel dimensions matter; the DPI tag is just a label that can be changed without altering the image.
What about megapixels? A 12 megapixel photo (4,000 x 3,000) can make a good A3 print at about 240 DPI, but a phone image sent through an app may be much smaller.
Quality depends on the printer, paper and viewing distance. These figures are guides.