Tools › Converters › DPI Calculator
Convert between millimeters and pixels at a given resolution (DPI) — for print preparation and scan settings.
Your input is never sent to a server — everything runs in your browser
How to use
- Choose the direction (mm → pixels or pixels → mm).
- Enter the value and the resolution — common DPIs are one tap away.
- The result appears automatically.
Quick reference (computed with the same formula)
| Purpose | Size | At 300 dpi |
|---|
| A4 | 210 × 297 mm | - |
| US Letter | 216 × 279 mm | - |
| 4×6" photo | 102 × 152 mm | - |
Screens are typically 72–96 dpi, standard printing is 300 dpi, and commercial printing often uses higher. The formula is px = mm ÷ 25.4 × dpi.
FAQ
How many pixels do I need to print a photo on A4?
About 2480 × 3508 pixels at 300 dpi (see the table above). Smaller images will look soft when enlarged to fill the page.
Is my input sent anywhere?
No. Everything runs inside your browser.