Image DPI Changer

Set JPEG/PNG print density without resizing or pixel re-encoding; verify preserved image data.

Change print-density metadata, not image detail. JPEG and still PNG only, up to 10 MiB. Your image stays in this browser.

Choose image for density

Target print density (DPI / PPI)

Whole number 1–12,000. Both pixel axes receive the same target. DPI metadata does not sharpen or resize the picture.

What stays unchanged, and what can be refused?

The editor normalizes supported JFIF/main-image EXIF and PNG density tags. Other metadata can remain, including location data and thumbnails. It is not a metadata scrubber, image repair service or print certification. Files with unreadable/duplicate EXIF, XMP, Photoshop/IPTC or PNG text metadata are refused to avoid conflicting density. Some apps ignore density tags; always check the saved copy in your print workflow.

This tool runs entirely in your browser. Your data is never uploaded, never stored, and never leaves your device.

Change supported JPEG/PNG print-density tags locally while preserving compressed image data, stored dimensions and orientation; metadata-only edits do not create sharper detail.

How to use it

1Choose one supported JPEG or still PNG up to 10 MiB.
2Review existing tags and select a whole-number target from 1 to 12,000 DPI.
3Create the copy, review preservation checks and verify it in the receiving print app.

Example

Input: 600 × 400-pixel PNG Target: 300 DPI
Output: 600 × 400 pixels preserved pHYs: 11,811 × 11,811 pixels/metre Recorded PNG density: 299.9994 DPI Nominal print size at target: 2.000 × 1.333 inches

PNG density rounding is expected. No additional image detail is created; the receiving app controls actual print scaling.

What happens to your data

Image bytes stay local. Other metadata, including GPS and thumbnails, can remain; this is not a privacy scrubber. Clear invalidates local state, not previously downloaded files.

Last updated October 2026

Change image DPI when a print or document workflow needs a supported JPEG or PNG file labelled with a particular density. Choose a whole-number target such as 300 DPI, create a separate copy and inspect the recorded tags before downloading. Pixel dimensions and compressed image data are checked for exact preservation.

This is a print-density metadata editor, not an upscaler. A 600 × 400-pixel picture remains 600 × 400 pixels at every density. Labelling it 300 DPI describes a nominal 2 × 1.333-inch print at that density; it does not create extra detail or make the original sharper. The receiving app can ignore or override the tags.

How it works

The browser reads one nonempty JPEG or still PNG up to 10 MiB. The structural reader checks segment/chunk bounds, ordinary JPEG scan framing and PNG CRC-32 values, rejecting incomplete, animated or unsupported compound files. It does not decode the compressed pixels or certify that an image decoder will accept every file. Keep the original and check the saved copy in the app used by the recipient.

The requested density must be an integer from 1 to 12,000. Both stored pixel axes are assigned the same density. A present JPEG JFIF header is normalized to pixels per inch. Main-image EXIF IFD0 density values are replaced together, using a newly appended directory while retaining original relative offsets for other entries. If a JPEG has neither JFIF nor EXIF, a minimal EXIF density container is added without introducing a JFIF color hint. Existing EXIF orientation is preserved; print-size calculations use the orientation-adjusted displayed dimensions. Thumbnail-specific density is not rewritten.

PNG uses a pHYs chunk containing whole pixels per metre. The target DPI is divided by 0.0254 and rounded to the nearest whole pixels-per-metre value; its CRC is recomputed. For example, 300 DPI becomes 11,811 pixels/metre, or 299.9994 DPI. Any existing supported main-image EXIF density is normalized too. This small representational rounding is shown rather than hidden.

The resulting file is parsed again. Dimensions and orientation must match, each supported physical density must agree with the target within PNG rounding, and every non-density container byte must match the original sequence. This includes compressed JPEG scans or PNG IDAT data. Failure produces no downloadable output. These checks establish metadata-edit preservation, not improved quality, decoded-image validity or print certification.

Unreadable or duplicate EXIF, malformed density tags, XMP, Photoshop/IPTC and PNG text metadata are refused. Such containers can carry competing resolution information, so this focused editor does not guess at which value an application will use. A full metadata editor is the better option for those files. Other supported metadata, including GPS data and embedded thumbnails, may remain. Original EXIF bytes can remain as unreferenced data after a directory replacement; this tool is not a privacy scrubber.

The source is not uploaded, resized or intentionally pixel-reencoded. Surrounding website assets and anonymous usage events may still use the network. Clear removes the local selection and temporary download link. Changing a setting invalidates the previous result; files already downloaded to your device are not deleted.

Worked example: Set density without inventing pixels

Input: 600 × 400-pixel PNG Target: 300 DPI
Result: 600 × 400 pixels preserved pHYs: 11,811 × 11,811 pixels/metre Recorded PNG density: 299.9994 DPI Nominal print size at target: 2.000 × 1.333 inches

PNG density rounding is expected. No additional image detail is created; the receiving app controls actual print scaling.

Common use cases

Preparing a supported JPEG/PNG for a workflow requesting 300-DPI metadata
Correcting inconsistent supported JFIF and main-image EXIF density tags
Labelling print density while keeping compressed image data unchanged
Checking the difference between density metadata and actual pixel resolution

Frequently asked questions

Does changing an image to 300 DPI improve its quality?＋

No. This tool changes supported print-density tags only. A 600 × 400 image still has 240,000 pixels. To obtain more genuine detail, start with a higher-resolution source; changing metadata cannot reconstruct detail.

What is the difference between DPI, PPI and pixel dimensions?＋

Pixel dimensions are the number of image samples. PPI describes image pixels per physical inch; printer DPI concerns printer dots. Image workflows often label the PPI metadata as DPI. This editor uses that familiar label while showing physical-size calculations explicitly.

Is the output recompressed or resized?＋

No pixel re-encoding or resizing is performed. Before offering a download, the editor compares the original and output non-density bytes, including compressed image data, and checks unchanged dimensions and orientation.

Why does my PNG show 299.9994 instead of exactly 300 DPI?＋

PNG stores density as whole pixels per metre rather than arbitrary DPI. The nearest value to 300 DPI is 11,811 pixels/metre, equivalent to 299.9994 DPI. Apps commonly round the display, and some ignore the tag entirely.

Can this fix conflicting JPEG JFIF and EXIF density?＋

Supported JFIF and main-image EXIF IFD0 tags are normalized together. Files with unreadable or duplicate EXIF, malformed density or potentially competing XMP/Photoshop/IPTC metadata are refused rather than producing a falsely consistent-looking result.

Can I use a TIFF, PDF, HEIC or animated image?＋

No. This focused metadata editor accepts supported JPEG and still PNG files up to 10 MiB. It is not a PDF effective-resolution editor or a multi-frame image processor. Use an appropriate format-specific editor for those files.

Does it remove location data or every old metadata value?＋

No. Other metadata and embedded thumbnails may remain, and original EXIF bytes can remain unreferenced. Use the separate Image Metadata Remover when privacy removal is your goal; inspect its limitations too.

Why does my print app still show another size?＋

Applications can ignore density tags, apply page-fit settings or use their own layout scaling. Reopen the saved copy in the actual print workflow and verify its scaling. These metadata checks are not print certification.