Millimetres to Pixels Converter

Convert millimetres (mm) to pixels (px) with precision. This free converter supports multiple DPI/PPI values for screen display, web design, and print projects. Whether you’re working on digital graphics, responsive layouts, or preparing images for print, this converter provides accurate mm to px conversions instantly.

Enter Millimetres (mm):

Select DPI/PPI Resolution:

Enter Custom DPI:

Conversion Result:

0 px

Conversion Formula

The formula to convert millimetres to pixels:

de>Pixels = (Millimetres ÷ 25.4) × DPI

Where 25.4 is the number of millimetres in one inch. Since DPI (Dots Per Inch) or PPI (Pixels Per Inch) measures pixel density per inch, we first convert millimetres to inches, then multiply by the resolution.

Alternative Formula

de>Pixels = Millimetres × (DPI ÷ 25.4)

This simplified version provides the same result and is often easier to work with when programming or creating spreadsheets.

Step-by-Step Conversion Process

Identify the millimetre value you want to convert (e.g., 50 mm).
Determine the DPI/PPI of your target device or output. Common values are 96 DPI for screens and 300 DPI for print.
Divide the millimetre value by 25.4 to convert to inches (50 ÷ 25.4 = 1.9685 inches).
Multiply the result by the DPI to get pixels (1.9685 × 96 = 188.98 pixels).
Round the result to the nearest whole number if needed (189 pixels).

Quick Conversion Tables

96 DPI (Standard Screen Resolution)

Millimetres (mm)	Pixels (px)

300 DPI (High-Quality Print)

Millimetres (mm)	Pixels (px)

Visual Comparison

10mm at 96 DPI

37.8 × 37.8 pixels

25mm at 96 DPI

94.5 × 94.5 pixels

50mm at 96 DPI

189 × 189 pixels

Common Use Cases

Web Design

Convert physical measurements from design mockups to pixel values for CSS. Most screens operate at 96 DPI, though retina displays may require 2x or 3x multipliers for high-density pixels.

Print Design

Prepare digital images for print by converting millimetre specifications to pixels at 300 DPI. Professional printing typically requires 300 DPI for sharp, high-quality results.

Graphic Design

Match physical dimensions when creating digital artwork. Convert ruler measurements or print specifications into precise pixel dimensions for your design software.

Photography

Determine image dimensions for photo prints. Convert the desired print size in millimetres to pixels to ensure your image resolution meets print requirements.

Mobile Development

Convert physical device dimensions to pixels for accurate mobile interface design. Different devices have varying DPI values, affecting how elements display on screen.

UI/UX Design

Transform physical spacing and measurement specifications into pixel-perfect digital interfaces. Maintain consistent sizing across different screen densities and resolutions.

DPI vs PPI Explained

DPI (Dots Per Inch) refers to print resolution – the number of ink dots a printer places on paper per inch. Printers use multiple dots to create colour variations and gradients.

PPI (Pixels Per Inch) describes digital image resolution – the number of pixels displayed per inch on a screen or in a digital image file. Each pixel contains a complete colour value.

Though often used interchangeably, DPI applies to physical print output whilst PPI describes digital displays. For screen work, 96 PPI is standard; for professional printing, 300 DPI is typical.

Resolution Standards

72 DPI

Legacy screen standard from early Macintosh computers. Rarely used today but still appears in some web specifications and older design guidelines.

96 DPI

Modern standard screen resolution for Windows and most web browsers. Default setting for most desktop monitors and laptops. Ideal for web content and screen display.

150 DPI

Medium-quality print resolution suitable for newsletters, flyers, and general business documents. Acceptable for images viewed from a moderate distance.

300 DPI

Professional print standard for high-quality output. Required for magazines, brochures, posters, and professional photography. Ensures sharp, detailed prints.

Conversion Examples

Example 1: Business Card

A standard UK business card measures 85mm × 55mm. At 300 DPI for print:

Width: (85 ÷ 25.4) × 300 = 1004 pixels

Height: (55 ÷ 25.4) × 300 = 650 pixels

Example 2: A4 Document

An A4 page measures 210mm × 297mm. At 300 DPI:

Width: (210 ÷ 25.4) × 300 = 2480 pixels

Height: (297 ÷ 25.4) × 300 = 3508 pixels

Example 3: Website Banner

A banner measuring 200mm wide for screen display at 96 DPI:

Width: (200 ÷ 25.4) × 96 = 756 pixels

Frequently Asked Questions

What DPI should I use for screen display?

For standard screen display, use 96 DPI (also called 96 PPI). This is the default resolution for most computer monitors and web browsers. However, high-density displays like Retina screens may have 2x or 3x pixel density, meaning they pack more physical pixels into the same space.

Why is 25.4 used in the conversion formula?

The number 25.4 represents the exact number of millimetres in one inch (1 inch = 25.4mm). Since DPI measures dots or pixels per inch, we must first convert millimetres to inches before applying the DPI multiplier.

Can I convert pixels back to millimetres?

Yes, reverse the formula: Millimetres = (Pixels ÷ DPI) × 25.4. You’ll need to know the DPI value used for the original conversion to get an accurate result.

What resolution should I use for printing?

For professional printing, use 300 DPI. This provides sharp, detailed prints suitable for brochures, posters, and photography. For everyday documents, 150 DPI may suffice, whilst large format prints viewed from a distance can use lower resolutions like 100-150 DPI.

Does screen size affect the conversion?

No, the mm to pixels conversion depends solely on DPI/PPI, not physical screen size. However, a larger screen at the same resolution will make pixels appear bigger, whilst a smaller screen at the same resolution will make pixels appear smaller. The conversion formula remains the same.

How do I find my screen’s DPI?

Most desktop monitors operate at 96 DPI (Windows standard) or 72 DPI (legacy Mac standard). High-density displays like Retina, 4K, or mobile screens have higher PPI values. You can check your device specifications or use an online DPI detection tool to determine your screen’s exact pixel density.

Is DPI the same as PPI?

Technically, no. PPI (Pixels Per Inch) refers to digital screens and image files, whilst DPI (Dots Per Inch) refers to print output. However, the terms are often used interchangeably in digital design. For conversion purposes, they function identically in the formula.