About this calculator
Print sharpness depends on dots per inch (DPI): the same photo prints smaller at a higher DPI and larger at a lower one. This calculator uses your photo's pixel dimensions to find the maximum size you can print at a chosen DPI — and, the other way around, lets you pick a target print size (a photo-lab size or a standard paper size like A4) to see the minimum pixel size it needs and whether your current photo measures up.
How the calculation works
The maximum print size in inches is your photo's pixel count divided by DPI. Width and height are calculated separately, and a cm value is shown using 2.54 cm per inch. If you already have a target print size, width and height in inches × DPI gives the pixels you need, and the product of the two is the required megapixels.
The upscale factor in the advanced section is the square root of required megapixels divided by current megapixels. At 1 or below no enlargement is needed, up to 1.3 is minor, up to 2 is moderate, and above 2 is a major shortfall.
Worked examples
- A 6000×4000 px photo (about 24 MP) can print up to about 20.0×13.3 in (about 50.8×33.9 cm) at 300 DPI, or about 40.0×26.7 in at 150 DPI.
- An 8×10 in print at 300 DPI needs 2,400×3,000 px (7.2 MP), and A4 (8.27×11.69 in) needs about 2,480×3,508 px (8.7 MP). A 24 MP photo has plenty of headroom.
- 16×20 in needs 4,800×6,000 px (28.8 MP), an upscale factor of about 1.10 for a 24 MP photo, and A2 needs about 4,961×7,016 px (34.8 MP), about 1.20. Both are minor, so ordinary resizing is enough.
- 20×30 in needs 6,000×9,000 px (54 MP), about 1.5, and A1 needs about 7,016×9,933 px (69.7 MP), about 1.7. In this range an AI upscaler can help.
When to use it
Use it before ordering a framed print, an album or a poster, to check that your photo's resolution is enough. It is also handy when you wonder how large you can print, or when choosing a camera and estimating the megapixels a given print size needs.
Limits and common mistakes
- 300 DPI is the benchmark for prints viewed up close. Large posters and banners viewed from a distance often look sharp at 150 to 200 DPI.
- If you cropped the photo, enter the pixel size after cropping. Entering the original camera size will say you can print larger than you really can.
- For print sizes with a different aspect ratio (for example a 3:2 photo printed at 4:5), the edges get cropped, so the actual layout can differ from the calculated result.
- Falling short on pixels does not always mean re-shooting. At 1.3× or below, ordinary resizing is often enough.
- Real print quality also depends on the print shop's equipment and paper.
Guides that pair well with this calculator
300 DPI is commonly treated as the 'photo quality' benchmark, but large prints viewed from a distance (posters, banners) often look just as sharp at 150–200 DPI. Actual print quality also depends on the print shop's equipment and paper.
Frequently Asked Questions
Do I really need 300 DPI?+
Not always. 300 DPI is a common benchmark for prints viewed up close (albums, framed photos), but large posters or banners viewed from a distance can look plenty sharp at around 150 DPI. The farther the viewing distance, the lower the DPI you need.
If my resolution is too low, do I always need to re-shoot?+
No. If the shortfall is small (an upscale factor of 1.3x or less in the advanced section), ordinary resizing is often enough, and an AI upscaler is a solid option beyond that. Re-shooting or choosing a smaller print size is really only worth recommending once the factor passes about 2x.
What's the difference between photo print sizes and paper sizes like A4?+
Photo print sizes (4×6, 8×10, etc.) are the inch-based sizes common at photo labs, while sizes like A4/A3 are ISO standard sizes used for office and general printing. This calculator offers both as presets, plus a 'Custom' option for anything else.