Pixel to Millimeter Converter

The number of millimeters in a pixel depends on the DPI (Dots Per Inch) or PPI (Pixels Per Inch) of the display/print:

Higher DPI means smaller pixel size in millimeters, which is why high-resolution prints have sharper details.

DPI and PPI are often used interchangeably but have distinct meanings:

For conversion purposes, DPI and PPI can be used interchangeably since the mathematical relationship (25.4 mm per inch) remains the same.

DPI is critical because pixels are a relative unit (resolution-dependent), while millimeters are an absolute unit (fixed physical size):

• Without DPI, there is no fixed conversion between px and mm
• A 100px element at 96 DPI is ~26.46mm wide, but at 300 DPI it's only ~8.47mm wide
• Choosing the correct DPI ensures your digital design translates accurately to physical size
• Web design typically uses 96 DPI, while print design uses 150-300 DPI
• Incorrect DPI can lead to oversized/undersized prints or misaligned elements

This converter lets you switch between common DPI values to match your specific project needs.

Convert px to mm when bridging digital and physical media. Common use cases include:

For pure digital projects (websites, apps, social media), pixel measurements are sufficient. Millimeter conversions are only needed when physical output is involved.

Yes, using the correct DPI for your printing needs ensures accurate mm to px conversion for high-resolution projects:

• Use 300 DPI for professional prints (photos, business cards, brochures)
• Use 150 DPI for large-format prints (posters, banners) where distance reduces the need for extreme detail
• Use the formula: px = mm × (DPI / 25.4)
• For a 50mm wide business card at 300 DPI: 50 × (300 / 25.4) = ~590.55 px
• Always round to whole pixels (digital images can't have partial pixels)

Most professional printing services require 300 DPI images for the sharpest, highest-quality results. This converter automatically applies the correct formula based on your selected DPI.