How to resize an image on Mac
To set exact dimensions, open the image in Preview, choose Tools › Adjust Size, enter the new width or height, and save. Finder’s Quick Actions › Convert Image can also make a smaller copy in Small, Medium or Large. If your real goal is a smaller file for an upload or email, FileMate’s Compress Image does that from Finder, and its stronger levels reduce the dimensions for you.
All of these run on your Mac. None of them upload the image.
Make an image smaller with FileMate
- Right-click the image in Finder and choose FileMate › Compress Image.
- Safe keeps the dimensions and makes the file smaller.
- For fewer pixels, click Want a smaller file? and try Stronger or Maximum. JPEG and HEIC images are limited to 2048 px on the longest side at Maximum; PNG and TIFF to 2560 px at Stronger and 1600 px at Maximum.
FileMate doesn’t resize to a width you type. For exact dimensions, such as 1080 × 1080 for a profile photo, use Preview’s Adjust Size.
Resize an image in Preview
- Open the image in Preview.
- Choose Tools › Adjust Size.
- Keep Scale proportionally ticked and enter a new width or height in pixels. Preview shows the resulting file size underneath.
- Click OK, then File › Export to save a copy under a new name.
Use Export, not Save: Preview saves changes to the open file automatically, so resizing the original replaces its pixels.
Resize from Finder with Quick Actions
Right-click one or more images and choose Quick Actions › Convert Image. Pick a format and an Image Size: Small, Medium, Large or Actual Size. macOS saves resized copies next to the originals. You can’t type an exact size, but it’s quick for several photos.
Resize or compress?
- Resizing changes the number of pixels: 4000 × 3000 becomes 2000 × 1500.
- Compressing changes how much data stores those pixels, without changing the dimensions.
They are related but not the same. A website that asks for “at least 1200 px wide” cares about dimensions. A form that says “maximum 2 MB” cares about file size, and compression alone often gets there without touching the dimensions. See how to reduce an image’s file size.
Which size do I need?
| Use | Typical size (longest side) |
|---|---|
| Profile photo | 400 to 1080 px |
| Photo in an email | 1200 to 2000 px |
| Website image, full width | 1600 to 2560 px |
| Printing at 15 × 10 cm (6 × 4 in) | About 1800 px |
| Printing at A4 | About 3500 px |
Get FileMate
For exact dimensions, Preview has you covered. For the everyday version, a photo that’s too heavy to send, FileMate makes a smaller copy from Finder, on your Mac.
Normal price €9.99, now €4.99 incl. VAT
One payment, no subscription. macOS 14 Sonoma or later, Apple silicon or Intel.