Image DPI Changer

About Image DPI Changer

DPI (dots per inch) is metadata that tells printers and Office apps the intended physical size of an image — pixel dimensions don't change, only the printed size does. A 300 DPI photo at 1200×1800 prints as 4×6 inches; the same photo at 72 DPI claims it should print as ~16×25 inches. Print labs reject photos under 300 DPI; LinkedIn and websites prefer 72 or 96 DPI metadata. This tool rewrites the DPI metadata directly: for JPG it edits the JFIF density bytes, for PNG it inserts or replaces the pHYs chunk. The pixel data is byte-for-byte identical to the source — only the metadata changes. No re-encoding, no quality loss, no canvas round-trip. Output is the source file with patched metadata. Files never leave your browser. Perfect for print preparation, resume photo requirements, and any workflow where the DPI tag matters.

Why use Image DPI Changer

• True metadata edit — JPG JFIF density bytes and PNG pHYs chunk are patched directly. No canvas re-encoding means zero quality loss and the output is byte-for-byte identical to the source apart from the metadata change.
• Pixel dimensions stay exactly the same — the DPI tag is purely metadata. A 1200×1800 image at 72 DPI versus 300 DPI is identical at the pixel level, only the implied print size in inches changes.
• 5 preset DPI values plus custom input — 72 (web), 96 (Office default), 150 (draft print), 300 (commercial print), 600 (fine art print). Type any value from 1 to 9999 for unusual requirements.
• Print size preview — the result panel shows the calculated print size in both inches and centimetres at the new DPI, so you can verify the photo will print at the right physical size.
• 100% browser-local — your photos never leave your device. ID photos, passport scans, resume photos, and design assets all stay private throughout the metadata edit.
• Lossless and instant — DPI patching is a metadata change, not a pixel re-encode. Output is generated in milliseconds even for very large files (50 MB photos process instantly).

How to use Image DPI Changer

1. Drop a .jpg or .png file onto the upload zone (WebP and other formats don't carry DPI metadata).
2. Pick a target DPI from the presets (72 web, 96 Office, 150 draft print, 300 print, 600 fine print) or type a custom value.
3. Click Change DPI — the tool reads the file's binary structure and patches the DPI metadata bytes directly, no canvas re-encoding.
4. Review the print size at the new DPI — the tool shows the resulting inches and centimetres at your chosen DPI value.
5. Download the patched file with the new DPI tag — pixel data is identical to the source, only the metadata changes.
6. Use the file in your print workflow, resume submission, or any application that reads DPI metadata.

When to use Image DPI Changer

• Submitting a photo to a print lab that requires 300 DPI — most labs reject photos at 72 DPI even when the pixel dimensions are sufficient for high-quality printing.
• Preparing a passport photo, visa photo, or ID photo for a government form that specifies a minimum DPI value alongside pixel dimensions and file size.
• Setting 72 DPI metadata on website images so design tools and CMS uploaders show the correct on-screen size, even though browsers ignore DPI for rendering.
• Updating a resume headshot's DPI to 300 before submitting to a recruitment portal or print magazine that requires print-ready DPI metadata.
• Building a design system asset library where every image needs a consistent DPI value (72 for web, 300 for print) for tooling consistency.
• Fixing a photo that won't print at the expected size in Word, PowerPoint, or InDesign because the embedded DPI tag tells the app to render it at the wrong scale.

Examples

Tips

• DPI is metadata, not resolution — to actually change the image's printable detail, you need to resize the pixel dimensions. Use Image Resize for that, then DPI Changer to set the metadata.
• Browsers ignore DPI metadata when rendering images on screen — every pixel is rendered at the screen's native pixel ratio. DPI only matters when an app calculates print size or imports for print.
• 300 DPI is the default for commercial print; 600 DPI is for fine-art reproductions and some passport requirements. Above 600, most printers can't actually resolve the extra detail.
• WebP doesn't have a standard DPI metadata location — that's why this tool only handles JPG and PNG. To set DPI on a WebP-sourced image, convert to JPG or PNG first using one of our format converters.
• If your file already has a pHYs chunk (PNG) or JFIF density (JPG), the tool overwrites the existing values. If neither is present, the tool injects a fresh metadata block.

Frequently Asked Questions

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Glossary

DPI (dots per inch)

A metadata value telling apps and printers the intended physical size of an image. 300 DPI means each printed inch contains 300 dots; the pixel dimensions divided by DPI give the print size.

JFIF density bytes

The DPI metadata location in a JPEG file. Bytes at offset 13-16 of the JFIF APP0 segment store the X and Y density. Units byte at offset 11 specifies inches (1) or centimetres (2).

PNG pHYs chunk

An ancillary PNG chunk storing pixels-per-meter for X and Y axes plus a unit byte. The chunk includes a 4-byte CRC32 checksum that this tool computes correctly when patching.

Print size

The intended physical dimensions of a printed image, calculated as pixel dimensions divided by DPI. A 3000-pixel-wide image at 300 DPI prints as a 10-inch-wide page.

PPI vs DPI

Pixels per inch (screens) and dots per inch (printers) are technically different but are used interchangeably in image metadata. Both refer to the same density value stored in the file.

Pixel data

The actual colour values of every pixel in the image. DPI is metadata — it does not affect pixel data. To change the number of pixels, you need to resize, not re-DPI.