Image DPI & Print Size Checker
Check whether an image has enough resolution to print at a given size.
An image that looks perfect on screen can print blurry, because a screen shows far fewer dots per inch than a printer needs. This checker reads your image's dimensions, works out the effective DPI at the print size you want, and tells you whether it will hold up.
Nothing is uploaded. Your image is read by your own browser and processed on a canvas element on your device. It never reaches a server, ours or anyone else's, and closing the tab discards it entirely.
Enter your details
Result
Fill in the fields above and your result will appear here.
What the Image DPI & Print Size Checker does
DPI — dots per inch — is not a property of an image file. It is the result of dividing the pixels you have by the physical size you want to print. The same 2,000 pixel wide image is 200 DPI printed at 10 inches wide and 400 DPI printed at 5 inches.
That is why "high resolution" only means something relative to an intended print size. This tool makes the relationship explicit, and reports the largest size the image can print at 300 DPI.
How to use this tool
- Drop any image onto the upload area — the tool reads its pixel dimensions locally.
- Choose the print size you intend, from A4 to a 4 × 6 photo, or enter a custom size in millimetres.
- Read the effective DPI and the quality verdict.
- If it falls short, the tool tells you how many pixels you would need for a sharp print at that size.
- Use the best-size-at-300-DPI figure to find the largest print the image can support.
How DPI is calculated
DPI = Pixels ÷ (Print size in millimetres ÷ 25.4)
The lower of the width and height figures is reported,
because that dimension limits sharpness.
Pixels needed for a sharp print:
Pixels = (Print size in mm ÷ 25.4) × 300
Quality bands:
300 DPI and above Excellent — photo quality
200 to 299 Good — fine for documents and ID
150 to 199 Acceptable at a distance
Below 150 Visibly soft in print
Worked example
Example: a 1,920 × 1,080 image printed on A4
| Image | 1,920 × 1,080 px (2.1 MP) |
| Print size | 210 × 297 mm (A4) |
| DPI across the width | 232 |
| DPI across the height | 92 |
| Effective DPI | 92 — too low |
| Needed for 300 DPI | 2,480 × 3,508 px |
A full HD screenshot is nowhere near enough for a full-page print. It would look fine at 4 × 6 inches, where it reaches around 180 DPI.
What your result means
300 DPI and above is photo quality and appropriate for anything examined closely, including ID photographs.
200 to 299 is fine for documents, reports and everyday printing.
150 to 199 works for posters and anything viewed from more than an arm's length.
Below 150 will look soft or pixelated. No software can add detail that was never captured — the answer is a higher-resolution original, not upscaling.
Important considerations
- DPI is not stored usefully in most image files. A file tagged "72 DPI" prints identically to the same file tagged "300 DPI" at the same physical size — only pixel count and print size matter.
- Viewing distance changes what is acceptable. A billboard at 20 DPI looks fine from across a road.
- Upscaling software can interpolate additional pixels but cannot recover detail. It reduces visible pixelation without genuinely improving sharpness.
- Screenshots are always low resolution relative to print, because screens are 96–160 DPI while print needs 300.
- For ID photographs, 300 DPI at the required physical size is the standard expectation, which is where the 413 × 531 pixel figure for a 35 × 45 mm photo comes from.
- Scanning a printed photograph at 600 DPI gives room to crop and still print well.
Limitations of this tool
- It reads pixel dimensions only and cannot judge whether an image is actually sharp — a blurry photograph at 300 DPI still prints blurry.
- It does not account for printer capability, paper type or ink, all of which affect perceived quality.
- Colour space and profile issues, which also affect print results, are outside its scope.
Frequently asked questions
What DPI do I need to print a photo?
300 DPI is the standard for photographic prints. 200 DPI is acceptable for documents, and 150 DPI is fine for posters viewed from a distance.
How many pixels for an A4 print at 300 DPI?
2,480 × 3,508 pixels — roughly 8.7 megapixels. Most modern phone cameras exceed this comfortably; screenshots and web images do not.
Can I increase the DPI of an image?
Only by printing it smaller, or by upscaling, which invents pixels rather than recovering detail. Changing a DPI tag in metadata does nothing to the actual image.
Why does my image look fine on screen but blurry when printed?
Because screens display around 96–160 dots per inch while printing needs about 300. An image that fills a screen may carry only a third of the detail a full-page print requires.