Print size & DPI calculator
Turn pixels and DPI into a real print size in inches, millimetres and centimetres, and work backwards to the pixels, effective DPI and quality grade a given print size needs.
Runs in your browserEvery computation happens in your browser — your data never leaves this device.
Pixels and DPI
Units: 1 in = 25.4 mm = 2.54 cm and 1 in = 96 CSS px (the CSS reference pixel); inches = pixels ÷ DPI and required pixels = inches × DPI, rounded up.
Target print size (optional)
Result
8.2677 in · Pixels required for that size 2481 px11.6929 in · Pixels required for that size 3508 px362.86 / 171.04 DPI0.8268Target DPI ÷ current DPI: above 1 means upscaling, which softens the image.
What this tool does
- You have a 3000×2000 photo and want to know how big it prints: at 300 DPI it comes out 10 in × 6.67 in (254 mm × 169 mm).
- Printing a sharp photo on A4: the paper preset works backwards to 2481 × 3507 pixels, so you know before the lab does.
- Judge whether a web image is usable: enter the target print size and read the effective DPI — 96 means find a bigger source.
- Checking print specs: 1 in = 25.4 mm and 1 in = 96 CSS px are both applied, so screen and print sizes convert either way.
Example
Input
Pixel width 3000, pixel height 2000, DPI 300, target size 210 mm × 297 mm (A4)
Output
Print width 10 in / 254 mm / 25.4 cm, print height 6.6667 in / 169.33 mm / 16.93 cm, 6 MP total, grade "Print quality (≥300 DPI)"; the A4 target needs 2481 × 3507 pixels and the effective DPI at that size is 362.93 / 236.55.
Effective DPI is pixels ÷ target inches: the width still has headroom while the height is already below 300 DPI, so a full-bleed A4 print would be slightly soft.
Frequently asked questions
Are DPI and PPI the same thing?
Strictly, PPI (pixels per inch) describes the image resolution while DPI (dots per inch) describes what the printer can output. Everyday usage mixes them, and this tool follows the common convention that inches = pixels ÷ DPI.
Why are required pixels rounded up?
A4 at 210 mm wide needs exactly 2480.31 pixels at 300 DPI. Using 2480 would leave a hairline of white or force stretching, so the tool always rounds up to 2481 — one pixel too many is harmless.
How much DPI is enough?
300 DPI for regular printing and photo labs, about 150 DPI for large posters viewed from a distance, and 72–96 DPI is plenty for screens. The grade is a rough guide; viewing distance and paper matter too.
What does 1 in = 96 CSS px mean here?
The CSS specification defines one inch as 96 CSS reference pixels, so a 768 px web image needs 2400 pixels to print 8 inches wide at 300 DPI. That conversion is what this tool uses to line web sizes up with print pixels.
Does it read or upload my image?
No. This is pure arithmetic on the numbers you type, computed in the browser — no file picker, no requests.
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