What Is DPI? How to Set Image Resolution for Print

STILL IMAGE GUIDES

In this guide

Understand DPI, pixels and physical print size. Learn what changing DPI does, how to calculate pixel dimensions and which metadata formats retain it.

DPI is a print-density relationship

DPI means dots per inch and describes how densely a printer places dots across a physical inch. Digital images themselves are made of pixels. To estimate print width, divide the image’s pixel width by the chosen DPI. A 1,200-pixel-wide image at 300 DPI corresponds to about four inches across, before any crop or printer-specific scaling.

Changing DPI cannot invent detail

If you change only the density metadata while keeping the pixel count fixed, the implied print size changes. If you specify a physical size and increase DPI, the output must contain more pixels. Resampling can create additional pixel values, but it cannot recover detail that was never in the original. A small source enlarged for print may still look soft.

Set a physical size carefully

Choose inches or centimetres, enter the desired dimensions, and set a DPI that matches the print provider’s workflow. The tool calculates the needed pixel dimensions. Keep proportions locked to avoid distortion. If the provider requests a particular crop, use the framing mode and check the preview before exporting.

Know where metadata is saved

Still writes print density metadata into JPG and PNG exports. The WebP workflow preserves pixel dimensions but does not write print DPI metadata. PDF export creates a page whose physical dimensions follow the selected DPI. Confirm the saved file in the software used for printing, because some apps ignore or reinterpret metadata.

Ask the printer for its requirements

There is no universal DPI number for every print. Viewing distance, printer capability, paper and intended dimensions all matter. Use the printer’s requested pixel size or resolution when available, and treat any general DPI example as a starting point rather than a guarantee of print quality.

Use the pixel-to-print calculation

For an uncropped image, divide pixel width by DPI to estimate print width in inches. For example, 1,800 pixels across at 300 DPI corresponds to 6 inches. To calculate the pixels needed for a known print width, multiply inches by DPI. Centimetres first convert to inches by dividing by 2.54. These calculations describe a relationship; the printer may resample or crop the file in its own workflow.

Separate metadata from resampling

Changing a DPI tag without changing the pixel count changes the implied physical print size, not the image detail. Resampling to a larger pixel count creates interpolated values, not captured texture that was missing from a small original. When entering a physical width and height in Still, the selected DPI determines how many pixels the export will contain. That can affect both visible sharpness and file size.

Keep proportions and crop in view

If width and height imply different ratios from the source, an editor must fit the whole picture, crop edges or distort the subject. Keep the ratio locked for ordinary print resizing. Use a crop only when the print layout calls for it, and inspect what gets trimmed. A correctly calculated pixel count can still produce the wrong composition if the print frame has another shape.

Check how the destination reads density

Still writes density metadata into JPG and PNG output. WebP does not receive print-DPI metadata in this workflow, although its pixel dimensions remain available. PDF output uses the chosen DPI to set page dimensions. Some software ignores or rewrites density fields, so reopen a test export in the application used by the print provider and confirm the physical size it reports.

Ask for the output specification

There is no single DPI value that suits every printer and viewing distance. A small close-up print can need a different pixel density from a large poster seen across a room. Ask the print shop for its preferred dimensions, bleed, colour mode, format and resolution. Treat generic DPI examples as a way to understand the math, then follow the real production specification for important work.

Convert centimetres using the same relationship

There are 2.54 centimetres in an inch. To find the pixels needed for a physical width in centimetres, multiply the centimetre value by the selected DPI and divide by 2.54. For example, 10 cm at 300 DPI needs about 1,181 pixels across. The browser rounds to whole pixels. Use the printer's requested values when available, since a crop or bleed changes the final printable area.

Choose a realistic input resolution

Before enlarging an image for print, compare its current pixel dimensions with the desired physical size. If a 900-pixel source is placed across a 10-inch print, it provides only 90 source pixels per inch before any resampling. Setting metadata to 300 DPI does not create the missing detail. A larger resampled file may satisfy a software field but can still look soft on paper.

Know what an application may do to metadata

Image viewers, office programs and print services do not all interpret density fields in the same way. One app may display the intended physical size while another uses only the pixel count and fits it to a page. Make a small test export and inspect it in the same workflow that will produce the final print. Confirm whether the provider wants a JPG, PNG or PDF and whether it will crop or resize the upload.

Keep pixel dimensions with the job notes

When handing an image to a designer or printer, state its pixel width and height along with the intended physical size and DPI. This avoids an ambiguous note such as '300 DPI' that says nothing about how large the source is. Keep the exported filename tied to the job or print size and retain the original. A clear handoff reduces surprises when another application opens the image.