DPI & Print Resolution Calculator
Work out the print resolution of an image from its pixel dimensions and printed size, the largest sharp print an image supports, or the pixels you need for a target DPI. Nothing is uploaded — the numbers stay in your browser.
Enter the pixel dimensions and the printed size (or pixels and a target DPI).
Pixels ↔ millimetres at a given DPI
Enter a pixel count and a DPI to convert.
DPI & Print Resolution Calculator — Pixels, Print Size and PPI
DPI (dots per inch) and PPI (pixels per inch) both describe how tightly pixels are packed when an image is printed. An image file has fixed pixel dimensions; DPI is what you get when those pixels are spread across a physical size. This calculator links the three — pixels, printed size and resolution — so you can see whether a file will print sharply, how big it can go, or how many pixels a target needs.
How the numbers relate
- DPI = pixels ÷ printed inches. A 1200 px image printed 4 in wide is 300 DPI.
- Max sharp print = pixels ÷ target DPI. At 300 DPI, 1200 px supports a 4 in (about 102 mm) width.
- Pixels needed = target DPI × printed inches. For 35 mm at 600 DPI you need about 827 px.
- 1 inch = 25.4 mm exactly, which is why mm, cm and inch give the same DPI for the same image.
The usual quality bands
Printers and photo labs quote broad bands rather than sharp cut-offs. The names below follow the common published scale; treat them as guidance, not a rule a portal will necessarily apply:
- Below 72 DPI — low; visibly soft in print.
- 72–150 DPI — screen territory; acceptable on a display, soft on paper.
- 150–300 DPI — good; fine for many everyday prints.
- 300–600 DPI — professional; the standard photo-print quality.
- 600 DPI and above — professional grade; high-detail work.
Why this matters for passport and visa photos
Several photo specs state a print resolution rather than a pixel count. The Maldives passport standard asks for at least 600 DPI printing (see the Maldives passport photo page); Belize asks for a high-resolution print (Belize passport photo). When a rule is written in DPI, the pixel size you need depends on the physical size — which is exactly what the converter above works out. A file can be the right mm size and still fail if it carries too few pixels for the required DPI.
Related tools
Resize the pixels with the resize-to-KB or image compressor; confirm a finished photo against one country's rules with the passport photo checker; lay out prints with the photo print sheet; and check a paper print you already have with the print size verifier. Browse every format on the photo size chart.
Frequently asked questions
Is DPI the same as PPI?
In everyday use they are treated as the same number: how many pixels (or dots) fit in one printed inch. Strictly, PPI describes an image file and DPI describes a printer, but the calculation is identical for our purpose.
How do I work out the DPI of my photo?
Divide the pixel width by the printed width in inches. For example, 1200 px across a 4 in print is 300 DPI. If your size is in mm, divide the mm by 25.4 first.
How many pixels do I need for a given DPI?
Multiply the target DPI by the printed size in inches. A 35 mm width at 600 DPI needs about 827 px; at 300 DPI, about 413 px.
How big can I print my image at 300 DPI?
Divide the pixel dimensions by 300. A 3000 × 3600 px image gives a 10 × 12 in (about 254 × 305 mm) print at 300 DPI.
Does changing the DPI resize my file?
No. Changing the DPI tag only changes the printed size interpretation; the pixel dimensions stay the same. To change sharpness you must change the pixels — resize up or down.
Will a high DPI guarantee acceptance?
No. Portals check several things — pixels, file size, head size and background among them. A correct DPI is only one requirement. Confirm the full rule on the country's official page before you submit.
Honest limits: this is arithmetic on the numbers you type, not a scan of your file — it does not read an image's embedded DPI metadata, and it does not know a portal's private thresholds. The quality bands are the common published scale, not an official standard. Confirm the exact figure on the destination's official page.
Related: photo size chart · passport photo checker · photo print sheet · print size verifier · all tools