How to Resize an Image on Mac (2026 Guide)

Introduction

Resizing images on a Mac is a common task, whether you're preparing photos for a website, social media, or print. Mac users have several built-in and third-party options for this — this guide covers Preview, Photos, Luminar Neo, and Instasize Web, plus tips for keeping quality intact.

How to Resize an Image Using the Preview App

Preview is built into every Mac and handles resizing without any extra software:

1. Open the image in Preview. Double-click the file, or right-click it, choose Open With, and select Preview.
2. Open the resize tool. Go to Tools > Adjust Size in the menu bar.
3. Set new dimensions. Enter your desired width and height. Keep Scale proportionally checked to avoid distorting the image, and make sure Resample image is checked if you're changing the pixel dimensions rather than just print size.
4. Apply. Click OK.
5. Save. Use File > Save, or File > Save As to keep the original file untouched.

How to Resize an Image Using the Photos App

The Photos app resizes on export rather than in the main editing view:

1. Open Photos and select the image.
2. Go to File > Export > Export 1 Photo.
3. Pick a size. The export window's Size dropdown offers Small, Medium, Large, Full Size, or Custom — choose Custom to enter exact pixel dimensions.
4. Export. Click Export, choose a save location, and confirm.

Note this creates a resized copy — your original stays untouched in your Photos library either way.

How to Resize an Image Using Luminar Neo

Skylum's Luminar (now branded Luminar Neo) is a paid photo editor with more advanced resizing and export controls than Apple's built-in apps. Unlike Preview, Luminar Neo resizes at export time rather than in the main editing panel:

1. Open your image in Luminar Neo and make any edits.
2. Go to File > Export.
3. Use the Resize dropdown in the export dialog — choose Long Edge and enter your target pixel dimensions.
4. Export to save the resized file.

Luminar Neo is worth it if you're already using it for editing; for a quick resize alone, Preview is faster.

How to Resize an Image Using Instasize Web

Instasize Web image resizer works directly in the browser without installing anything:

1. Go to Instasize Web and upload the image you want to resize.
2. Choose an aspect ratio or enter custom dimensions. Use Fit to keep the whole image (adds background space if needed) or Fill to crop tightly to the new dimensions.
3. Export. Download the resized file, or create a shareable image link for the hosted image.

Because it runs in the browser, it works the same on Mac, Windows, and mobile — useful if you switch devices often.

Tips for Resizing Images on a Mac

• Lock the aspect ratio unless you specifically want to stretch or squash the image — an unlocked ratio distorts faces and straight lines noticeably.
• Match resolution to purpose. Web images only need to be as large as they'll display (commonly 72–150 PPI); print needs 300 PPI or higher.
• Keep a backup of the original. Preview's Save As and Photos' Export-a-copy both protect your source file, but it's worth confirming before resizing anything you can't easily re-download.
• For batch resizing many photos at once, a dedicated tool (Instasize Web, Luminar Neo, or Photoshop) is faster than resizing one-by-one in Preview. If the batch is headed to a contact sheet or collage print, follow the steps to print multiple images on one page after exporting the resized files.

FAQ

What's the fastest way to resize one image on a Mac? Preview's built-in Tools > Adjust Size — no extra software needed, and it's already on every Mac.

Does resizing in Preview reduce image quality? Scaling down loses some detail (as any resize does), but Preview doesn't add compression artifacts beyond whatever file format you save to. Scaling up doesn't add real detail back — start from the highest-resolution original you have.

Can I resize multiple images at once on a Mac without extra software? Preview can batch-select multiple images and apply Tools > Adjust Size to all of them at once, but each one uses the same target dimensions — there's no per-image customization in that batch flow.

Is Luminar Neo required to resize images on a Mac? No — Luminar Neo is a paid editor best suited to people already using it for broader photo editing. Preview, Photos, or Instasize Web all resize images for free.