Free Tool Desk

Image DPI Changer (No Resampling)

Change the DPI label of a JPEG or PNG without resampling: pixel size and image data stay exactly as they are. See before and after and the print size in mm and inches. In your browser.

Free to use No sign-up required Nothing is uploaded

A form says "upload a 300 DPI image" and your picture says 72. DPI is only a label stored in the file that tells a program how large to print each pixel. This tool rewrites that label and nothing else: the pixels are not resampled, the compressed image data is copied byte for byte, and the pixel dimensions stay the same.

You see the DPI before and after, and the size the image would print at in millimetres and inches, which is the only thing DPI really changes. Changing the label does not add detail.

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Overview

About Image DPI Changer

What is written. In a JPEG the resolution lives in the JFIF header (units and X/Y density). If the file has no JFIF header, one is added at the start; if the file has an Exif block with X and Y resolution, those tags and the resolution unit are updated too, so programs that read Exif do not contradict JFIF. In a PNG the resolution is the pHYs chunk, given in pixels per metre: the tool writes the value for your DPI (rounded to whole pixels per metre) and keeps every other chunk, including the image data, unchanged.

DPI versus pixels. A 2480 × 3508 pixel image is A4 at 300 DPI (210 × 297 mm) and a poster at 72 DPI (875 × 1237 mm). It is the same picture with the same detail; only the intended print size differs. Asking for "300 DPI" without saying what size is meaningless: what a printer or a website really needs is enough pixels for the size you print. Resizing (resampling) changes the pixel count and is a different operation, available in the Resize Image tool.

Presets and custom. Presets for 72, 96, 150, 300 and 600 DPI, or any whole number from 1 to 65535. Files that already declare a DPI show it first, including both JFIF and Exif values when they differ.

Compatibility

Supported Formats

JPEG and PNG files up to 100 MB (decided by the content, not the name). Animated PNG, WebP, TIFF, GIF and BMP are not handled, because they store resolution differently or not at all. The output keeps the original format.

Guide

How to Use Image DPI Changer

  1. Choose a JPEG or PNG.
  2. Look at the DPI the file declares now and the pixel size.
  3. Pick a preset or type a DPI. The page shows the print size that results.
  4. Press Apply and download. The pixel size is unchanged; check the new DPI in the confirmation.

Highlights

Features

  • No resampling Pixel size and image data stay byte-identical; only the resolution label changes.
  • Before and after Shows the DPI the file declares now (JFIF, Exif, pHYs) and the new one.
  • Print size shown Converts pixels and DPI into millimetres and inches so the label means something.
  • Presets 72, 96, 150, 300, 600 or any whole number up to 65535.
  • Private by design Nothing leaves your device.

Applications

Use Cases

  • Satisfying an upload form that checks the DPI field of an image
  • Making a scan open at its real print size in a layout program
  • Setting a consistent DPI on images for a print-ready document
  • Removing a wrong DPI left by a screenshot or an export
  • Seeing what size a given pixel size prints at

Good to Know

Limitations

Changing DPI does not make an image sharper, larger or more detailed, and it does not change the number of pixels. If a requirement is really about pixel size (for example at least 1200 × 1600 pixels), the label alone cannot satisfy it. Some websites check the label, some check the pixels, some check both.

The label is metadata, and programs treat it differently: many web browsers ignore it, some editors reinterpret it when you open the file. A JPEG whose Exif block uses an unusual layout may keep an old Exif value even though the JFIF value is updated, and the tool says what it changed. Always check the result in the program you will use it in.

This tool runs entirely in your browser — your file is never uploaded to our servers. See our Privacy Policy for full details.

Support

Frequently Asked Questions

Does changing DPI resize or resample the image?

No. Pixel dimensions stay exactly the same, and the compressed image data is copied unchanged. Only the resolution label changes.

Will 300 DPI make my photo look better?

No. DPI only sets the intended print size. A 1000 × 1000 pixel image prints at 3.3 inches at 300 DPI, or about 14 inches at 72 DPI, with the same detail.

Is my image uploaded?

No. The label is rewritten in your browser and the new file is made there. Nothing is sent to our server, and file names are not sent to analytics.

Why does my form still say the DPI is wrong?

Some forms read DPI from Exif, some from JFIF or pHYs, and some check pixels instead. The tool updates JFIF and Exif together for JPEG. If it still fails, the form probably needs more pixels, which needs a resize.

Why are WebP and TIFF not supported?

WebP has no standard resolution field in its container, and TIFF stores it differently. The tool only edits formats where it can do so safely without touching the image data.

What is the difference between DPI and PPI?

In files they mean the same thing: pixels per inch of intended output. Printers also use DPI for ink dots, which is a different measurement.

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