Guide

How to upscale an image on a Mac

For a quick one-off, open the image in Preview and use Tools > Adjust Size to enter larger width and height values. For an exact size, 2×, 4× or 8×, a whole folder, or an AI option, use an upscaler such as MacnifyIt. Both routes are below.
Checked 24 Oct 2026 against Apple’s Preview User Guide and MacnifyIt 1.3.

Resolution and size are different things

Resolution here means the number of pixels in the image, such as 1,200 × 800. The “Resolution” box in Preview’s Adjust Size dialog is pixels per inch (PPI), which sets the printed size and, when Resample image is ticked, the pixel count. Changing PPI alone does not add pixels. To get a bigger image with more pixels, the app has to calculate new pixels from the ones you have. That is upscaling.

Option 1: Preview (built in)

  1. Open the image in Preview.
  2. Choose Tools > Adjust Size, or click the Adjust Size button in the Markup toolbar.
  3. Enter new values for width and height, or choose a size from the “Fit into” pop-up menu. To resize by a percentage, choose “percent” from the pop-up menu next to the fields.
  4. Tick Scale proportionally to keep the original proportions.
  5. Make sure Resample image is ticked when you want more pixels. Apple notes that unticking it makes the dimensions smaller without losing detail, so it is not the setting for enlarging.
  6. Save a copy (File > Export) so you keep the original.
These are Apple’s steps (Preview User Guide, checked 24 Oct 2026). Preview can also resize several images at once: show them in the same window, select them in the sidebar, then choose Tools > Adjust Size.
Preview is free and always there. Apple’s guide does not say which resampling method it uses, so look closely at the saved file.

Option 2: MacnifyIt

  1. Download MacnifyIt and open the image, drop in a folder, or right-click files in Finder and choose MacnifyIt.
  2. Choose the size: 2×, 4× or 8×, or set the longest side, an exact width, an exact height, a fit within a box, or a percent. You see the output dimensions before you start.
  3. Choose a method. Exact recalculates pixels from your pixels, so the result is the same picture, larger. Clarity is Exact plus a bounded sharpen of edges already in the picture. Neither uses AI. Enhance (AI) estimates additional detail on your Mac. Contains AI-estimated detail.
  4. Compare the source and the result at 100 % in the compare view.
  5. Export as PNG, JPEG, TIFF or WebP. A job receipt records how each export was made.
MacnifyIt is US$29 once for one Mac, with 12 months of updates and no subscription. The free trial gives you 12 full-resolution exports, unlimited previews, no account and no time limit. No images are uploaded for processing.
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Which should you use?

A quick, small enlargement of one file
Preview
An exact pixel size or print size
MacnifyIt
2×, 4× or 8×
MacnifyIt
A folder of images
MacnifyIt, or Preview’s multi-select for simple resizes
To choose between plain resampling and AI
MacnifyIt
Upscaling inside an image editor
The resize or Super Resolution command in your editor

Upscaling a screenshot

Screenshots of text have hard edges. Try Exact or Clarity first and compare at 100 %. If the screenshot is small, the larger file can look soft because there are no more pixels to show; a bigger original is better if you can get one.

Questions

How do I increase image resolution on a Mac?

Open the image in Preview, choose Tools > Adjust Size, enter larger width and height values with Resample image ticked, and save a copy. For exact sizes or batches, use an upscaler.

How do I change the resolution (PPI) of an image on a Mac?

In Preview’s Adjust Size dialog, the Resolution field sets pixels per inch. Changing it with Resample image unticked changes the print size without adding pixels.

Can I enlarge many photos on a Mac at once?

Yes. Preview can resize selected images together. MacnifyIt takes whole folders from the app or the Finder menu and shows per-file progress in an Export Queue.

Does enlarging an image make it look sharper?

Not by itself. Exact and Clarity make a bigger version of the same picture, so soft areas stay soft. Enhance (AI) estimates additional detail. Contains AI-estimated detail. Check the result at 100 %.

Is there a free way to upscale on a Mac?

Preview is free and built in. MacnifyIt has a free trial of 12 full-resolution exports, with unlimited previews and no time limit.

Try it on your own images.

12 full-resolution exports free. Unlimited previews. No account, no time limit.
Download for Mac
See pricing