Images
How to Increase Image Resolution on a Mac
To increase image resolution on a Mac, open the image in Preview, choose Tools > Adjust Size, keep Resample image checked and raise the width and height in pixels. That adds pixels. It cannot add detail that was never captured.
For a 2x to 4x enlargement that looks cleaner than simple stretching, use an upscaling app instead. Below: all three methods, with what I measured.
How do I make an image bigger in Preview?
- Open the image in Preview.
- Choose Tools > Adjust Size.
- Set the unit to pixels. Leave Scale proportionally on.
- Leave Resample image checked. If you uncheck it, Preview only changes the print size tag and the pixel count stays the same.
- Type the new width. The height follows. Click OK.
- Choose File > Export to save a copy, or File > Save to overwrite the original.
Preview enlarges by interpolation: it guesses the new pixels from their neighbors. Edges get softer as the factor goes up. A 10 to 25 percent increase is usually fine. Past 2x you will see it.
How do I increase resolution from Terminal?
Every Mac ships with sips. It resizes to an exact size or scales the longest edge. See the sips command guide for Mac for the full set of flags.
# exact size, height then width
sips -z 1200 1800 photo.jpg --out photo_big.jpg
# longest edge to 3000 px, keeps the aspect ratio
sips -Z 3000 photo.jpg --out photo_big.jpgI ran the first form on a synthetic 600 x 400 JPEG (71.8 KB), asking for 1800 x 1200. The result was 245.8 KB. The file is about 3.4 times larger because it holds more pixels, not because it holds more picture.
This is the same interpolation as Preview, scriptable. It suits a folder of small icons or thumbnails you need a little bigger. It does not rebuild detail.
Can I make an image bigger without losing quality?
Not literally. Every method invents pixels. What changes is how plausible the invention looks. Plain interpolation blurs. An AI upscaling model predicts texture and edges, so a 2x result often looks crisper than stretching, though it can also invent detail that was not there.
Smol has an Upscale operation for this: 2x, 3x or 4x, written as PNG, JPG or WebP. I ran a 2x upscale on the same 600 x 400 test JPEG and got a 1200 x 800 JPG of 236.9 KB in well under a minute on an Apple Silicon Mac. I make no claim that it beats other tools on your photo. Try it on a real file and judge the edges and skin or text yourself.
Upscaling is heavy on the GPU, so a large image at 4x takes noticeably longer than a small one at 2x. For a ranked comparison of dedicated apps, read the best AI image upscaler for Mac roundup.
Which method should I use?
| Method | Best for | Limit |
|---|---|---|
| Preview, Adjust Size | One image, up to roughly 2x | Interpolation only; soft past 2x |
| sips in Terminal | Scripts and folders of small images | Same softness as Preview; no AI |
| Smol Upscale | 2x, 3x or 4x on art, scans, old photos | Slower; outputs PNG, JPG or WebP; it can invent detail |
| Photos or Pixelmator-type editors | Careful single edits with masks | Manual work per image |
When does upscaling not help?
If the source is blurry from motion or missed focus, upscaling gives you a bigger blurry image. If it is heavily compressed, the blocky artifacts get enlarged along with everything else. Sharpness lives in the original capture.
Ask first if you need more pixels at all. A screen needs pixels for the size it shows. A print needs pixels for the paper size, which we cover in resizing photos for printing on Mac. If the image is only going on a web page, a smaller file is usually the real goal, and the best image compressor for Mac covers that.
Two details save trouble. First, upscale once, from the original, never from an already upscaled copy. Second, keep the output as PNG or high-quality JPG, then compress last if you need a smaller file.
When is Smol the wrong tool for this?
For one photo going from 1000 px to 1300 px, Preview is enough. For a script over a folder of small images, sips is faster than any app. For a hero image where every pixel matters and you want manual control, an editor with masking beats a one-click upscale.
Smol earns its price when you have a batch, a mix of formats, or old art and scans that need 2x to 4x, and you want it done locally with nothing uploaded. It is $29 once for one Mac, with no subscription: see Smol pricing. If you are weighing it against a high-end paid upscaler, see the Topaz Gigapixel alternative page.
How we checked this
Ran sips -z and Smol 2x Upscale on a synthetic 600 x 400 JPEG on an Apple Silicon Mac and read the output sizes and pixel dimensions. Checked Preview menu names from the macOS interface. Facts last checked . We make Smol, so treat our claims about it with the same care as any vendor’s, and see our editorial policy.
Increasing image resolution: common questions
Does Preview increase resolution without losing quality?
No. Preview enlarges by interpolation, which creates new pixels by averaging neighbors. The image gets bigger in pixel count but no sharper, and the softness is visible past about 2x. For a cleaner large result, use an AI upscaler, and expect it to guess at detail rather than recover it.
What is the difference between resolution and DPI?
Resolution is the pixel count, such as 3000 x 2000. DPI is a tag that says how many of those pixels go into each inch when printed. Changing DPI alone does not add pixels. To print larger without a soft result, you need more actual pixels or a smaller print.
How do I increase the resolution of a screenshot?
You cannot add real detail, but you can enlarge it. In Preview use Tools > Adjust Size with Resample image on, or run an upscaler for 2x. Text in screenshots often stays cleaner with an upscaler than with plain stretching. Retake the screenshot on a Retina display if you can.
Can I upscale a batch of images at once on a Mac?
Yes. A sips loop handles plain enlargement for a whole folder. Smol accepts whole folders and mixed file types in one batch for its Upscale operation, writing 2x, 3x or 4x copies next to the originals by default. Large images at 4x take longer, so start with a small test.
Why is my upscaled image a bigger file?
More pixels mean more data to store. In my sips test, a 600 x 400 JPEG of 71.8 KB became 245.8 KB at 1800 x 1200. If the file is now too heavy to send, compress the upscaled copy afterward rather than shrinking the pixels again.
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