How to Change Image DPI on Mac

Changing image DPI on Mac is possible with four methods: macOS Preview (free, built-in), GIMP (free download), Photoshop, or a browser-based DPI converter that requires no software. This guide covers each method with exact steps.

Method 1 — Change DPI in macOS Preview (Free, Built-In)

macOS Preview is the fastest method for most Mac users. It rewrites the DPI metadata stored in the image file.

  1. Open your image in Preview (double-click any JPG or PNG).
  2. Go to Tools in the menu bar, then click Adjust Size.
  3. Locate the Resolution field showing the current DPI value.
  4. Uncheck "Resample image" — this is critical to avoid rescaling pixels.
  5. Type your target DPI (e.g., 300) in the Resolution field.
  6. Click OK, then save the file with Cmd+S or File > Export.

Limitation: Preview works reliably with JPEG and TIFF. PNG DPI metadata handling can be inconsistent across macOS versions.

Method 2 — Change DPI in GIMP on Mac (Free)

GIMP is a free, open-source image editor that gives precise control over DPI without resampling.

  1. Open GIMP and load your image via File > Open.
  2. Go to Image in the menu bar, then click Print Size.
  3. Change the X Resolution and Y Resolution fields to your target DPI (e.g., 300).
  4. Click OK. GIMP updates DPI metadata without resampling pixels.
  5. Export via File > Export As and choose your format.

For the full GIMP DPI workflow, see our guide on changing DPI in GIMP.

Method 3 — Change DPI in Photoshop on Mac

  1. Open your image in Photoshop.
  2. Go to Image > Image Size (shortcut: Option+Cmd+I).
  3. Uncheck Resample at the bottom of the dialog.
  4. Change the Resolution field to your target value (e.g., 300 ppi).
  5. Click OK and save.

Full instructions are in our Photoshop DPI guide.

Method 4 — Free Online DPI Converter (No Software Needed)

A browser-based tool is the fastest option on any Mac, any macOS version, with no installation required.

  1. Open Safari or Chrome on your Mac.
  2. Go to the free online DPI changer.
  3. Upload your JPG, PNG, or WebP file.
  4. Select the target DPI (72, 96, 150, 300, or 600) or enter a custom value.
  5. Click Convert and download the result instantly.

Why Preview's Resolution Setting Can Be Misleading

When "Resample image" is checked in Preview, changing the resolution field physically rescales pixel dimensions to maintain the same print size at the new DPI. A 1000 x 1000 px image at 72 DPI becomes roughly 4166 x 4166 px at 300 DPI — a 17x file size increase. Always uncheck "Resample image" unless you intentionally want to upscale pixels.

Common DPI Values for Mac Printing Workflows

DPIUse Case
72 DPIWeb, email, social media
150 DPIDraft prints, large-format signage viewed from distance
300 DPIProfessional print — photos, brochures, business cards
600 DPIFine-detail technical documents, archival scanning

Need to change your image DPI right now?

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Frequently Asked Questions

Can I change DPI on Mac without Photoshop?
Yes. Use macOS Preview (built-in), GIMP (free), or a free online DPI converter at dpiconverter.online — no software installation required.
Does Preview on Mac actually change DPI?
Preview can change DPI metadata via Tools > Adjust Size > Resolution. Uncheck "Resample image" to change only the DPI tag without altering pixel dimensions.
What DPI should I use for printing on Mac?
300 DPI is the professional print standard for photos, brochures, and business cards. For web publishing, browsers ignore the DPI metadata entirely.
How do I check image DPI on Mac?
Open the image in Preview, go to Tools > Show Inspector (Cmd+I), and click the Info tab. It shows the current DPI. You can also use our free online DPI checker.
Does changing DPI in Preview reduce image quality?
If you uncheck "Resample image", changing DPI in Preview only rewrites metadata with no quality loss. If "Resample image" is checked, pixels are rescaled, which can introduce quality loss.