Pixel / DPI Converter

Convert pixels to inches, cm and mm at any DPI/PPI — for screen design and print work alike.

Type in any field — the others update as you go.
Find the DPI from pixels and print size
Required DPI / PPI
300

Every conversion runs in your browser. Nothing you type is uploaded to BroBroGo.

FAQ

What is the difference between DPI and PPI?

PPI (pixels per inch) is the pixel density of an image or screen; DPI (dots per inch) is how many ink dots a printer lays down. In export dialogs, print shops and image files the two terms are used interchangeably, and the math here is identical for both.

What DPI do I need for printing?

300 DPI is the usual standard for photo prints viewed up close. Posters and banners seen from a distance still look sharp at 150 or even 100 DPI. Print size in inches × DPI = the pixels you need — exactly what the converter above calculates.

Why do screens default to 96 DPI?

Web pages and desktop apps treat one logical inch as 96 pixels by convention, so 96 is the right default for on-screen sizes. Real displays vary a lot — many phones pack over 400 physical pixels per inch — so for a specific device, enter its actual PPI instead.

Written and reviewed by the BroBroGo editorial team.Last updated:

The Mathematical Relationship Between Pixels, Physical Size, and DPI/PPI

The conversion between digital pixels and physical dimensions relies on a simple mathematical relationship. Pixel density, expressed as DPI (dots per inch) or PPI (pixels per inch), acts as the scaling factor between the digital and physical worlds.

The core formula to find the physical size in inches is:

Inches (in) = Pixels (px) ÷ DPI / PPI (pixels per inch)

To convert the physical size to metric units, the tool applies standard conversion factors:

Centimeters (cm) = Inches (in) × 2.54 Millimeters (mm) = Inches (in) × 25.4

Conversely, if you know the target physical size and the pixel dimensions, you can calculate the required pixel density:

Required DPI / PPI = Pixels (px) ÷ Physical size (in)

For example, entering "300" into the DPI / PPI (pixels per inch) field and "3000" into the Pixels (px) field results in "10 in", "25.4 cm", and "254 mm". If you reverse the calculation by entering "600" into the Pixels (px) field and "2 in" into the Physical size field, the Required DPI / PPI output displays "300".

DPI vs. PPI: Pixel Density in Digital Images and Screens

While the terms DPI and PPI are frequently used interchangeably, they refer to different aspects of imaging. PPI (pixels per inch) refers to the pixel density of an image or screen, describing how many digital pixels are packed into one linear inch of a digital display. DPI (dots per inch) refers to the number of ink dots a printer lays down per inch when reproducing an image on paper.

For the purpose of mathematical conversion, the math is identical for both terms. Whether you are preparing a digital layout or setting up a print job, the calculation treats the density value as a direct ratio of pixels to inches.

Choosing the Correct DPI/PPI for Screen vs. Print

Selecting the appropriate pixel density depends entirely on the output medium:

  • Print Quality Standards: High-quality print reproductions, such as photographs and detailed brochures viewed at arm's length, typically require 300 DPI to ensure individual pixels or dots are invisible to the naked eye. For larger formats like posters and banners that are viewed from a distance, lower densities such as 150 DPI or 100 DPI are standard and sufficient to maintain visual clarity.
  • Screen Design and Web Standards: Web pages and desktop applications historically operate under a conventional standard of 96 DPI. This baseline ensures consistent rendering of user interface elements across standard desktop monitors.
  • Physical Display Characteristics: Modern hardware often departs from the 96 DPI convention. High-density screens, such as those on modern smartphones and tablets, feature physical PPI values that can exceed 400 PPI. When designing specifically for these devices, using their actual physical PPI yields accurate physical-to-pixel translations.

Tool Rules, Inputs, and Error Handling

The converter operates dynamically; typing in any field updates the others automatically. The tool accepts numerical inputs and enforces specific validation rules to ensure mathematical accuracy:

  • DPI / PPI (pixels per inch): Must be a number greater than 0. If the DPI is 0, derived values are cleared, and the error message "DPI must be a number greater than 0." is displayed. Quick-select presets are available for 72, 96, 150, 300, and 600 DPI. Using the "Copy" function on these presets writes the numerical value directly to the browser clipboard.
  • Pixels (px): Must be a non-negative number.
  • Physical Dimensions: Inches (in), Centimeters (cm), and Millimeters (mm) inputs must be non-negative numbers. If a size input is negative, the message "Sizes cannot be negative." is displayed.
  • Physical size (for finding DPI): Must be a number greater than 0. If a size input is 0 or negative, the result for "Required DPI / PPI" displays "—" and the error message "Pixels and size must both be greater than 0." is displayed.
  • General Validation: If any input is not a valid number, the tool displays the message "That is not a valid number.". Clearing any input field acts as a clear path for its corresponding calculations.

Browser-Based Processing and Privacy

This tool is designed with data privacy in mind. Every conversion runs in your browser. Nothing you type is uploaded to BroBroGo. All calculations are performed locally on your device, ensuring your design dimensions and project specifications remain private.

Frequently Asked Questions

What is the difference between DPI and PPI? PPI (pixels per inch) is the pixel density of an image or screen; DPI (dots per inch) is how many ink dots a printer lays down. In export dialogs, print shops and image files the two terms are used interchangeably, and the math here is identical for both.

What DPI do I need for printing? 300 DPI is the usual standard for photo prints viewed up close. Posters and banners seen from a distance still look sharp at 150 or even 100 DPI. Print size in inches × DPI = the pixels you need — exactly what the converter above calculates.

Why do screens default to 96 DPI? Web pages and desktop apps treat one logical inch as 96 pixels by convention, so 96 is the right default for on-screen sizes. Real displays vary a lot — many phones pack over 400 physical pixels per inch — so for a specific device, enter its actual PPI instead.

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