Need an image with translucency but only got a PDF? Your iPhone sent the image as HEIF (*.heic) but you need to publish it as a JPEG? Find out here how to convert images swiftly (and for free) on a Mac using macOS Preview to JPG, PNG, PDF, and more.
First, Nuts for Astronaut Food
When Apollo astronauts embarked on a journey to the earth’s moon, they left behind all fresh produce and food—except, legend has it, for a serving of pecan nuts.
The nuts are lightweight, after all, still nutritious, and keep for a long while at room temperature.
So, want to turn your images into a format you think will keep or trim their weight for a trip on the internet? Your Mac comes with an application for that:
How to Convert Images on a Mac (to JPG, PNG, GIF, PDF…)
Time needed: 3 minutes
To convert pictures and graphics between many image formats using macOS Preview on a Mac (to JPEG, PNG, GIF, PDF, HEIF, and more):
- Open the image you want to convert in Preview.
Here’s how: Click the image in Finder with the right mouse button and select Open With | Preview from the context menu that has appeared.
- Select File | Export… from the menu.
PDF: You need not choose Export as PDF… to convert an image to PDF.
- Select the image format for the conversion under Format:.
Which to pick: See below for an overview of image formats.
- Choose options for the conversion.
Quality: For lossy image formats, pick the tradeoff between compression and quality.
Resolution: Pick the image resolution for conversion in pixels per inch or centimeter (e.g., at least 300 dpi for printing and some 96 dpi for classic displays).
Alpha: If the original image has translucency, you can keep the alpha channel that encodes that in the converted image.
Compression: For some formats (namely TIFF), you can pick the compression algorithm; ZIP is typically a good choice.
More options: Some image formats come with special options; see below. - Optional: Change the file name and folder under Export As: and the folder browser.
- Click Save.
The default: How to Make Preview the Default for Opening PDF files on a Mac
How to Convert an Image on a Mac (Using Preview): Formats and Options
Preview on a Mac lets you convert to the following image formats:
| Image format | Best for | Options |
|---|---|---|
| HEIC | Pictures, like JPEG with alpha channel | Quality and Alpha: see above |
| JPEG | Pictures, no numbers and letters, for sharing | Quality: see above |
| JPEG-2000 | Pictures, older alternative to HEIC | Quality and Alpha: see above |
| OpenEXR | Storage of high-quality pictures and graphics | Alpha: see above Depth: How many different shades of each colorare possible |
| Documents for sharing and printing | Quartz Filter: Lets you convert PDF files to grayscale, for example Alpha: see above Create PDF/A: a format with few dependencies for archiving Create Linearized PDF: Makes it possible to show the PDF as it is downloaded or streamed; for longer documents | |
| PNG | Graphics for sharing | Alpha: see above |
| TIFF | Pictures for saving | Alpha: see above Compression: How much the image is compressed; LZW, ZIP, and PackBits are lossless, JPEG uses JPEG compression |
How to Convert Images in Mac Finder (Using Quick Actions)
To convert an image on a Mac right in Finder (and without even opening Preview):
- Click on the image with the right mouse button in Finder.
More than one: This conversion also works with multiple images selected, of course; each highlighted image will be converted individually. - Select Quick Actions | Convert Image from the context menu that has appeared.
No “Convert Image” quick action: See below for adding the image conversion quick action to Finder. - Choose the desired target format under Format:.
Default: The converter always defaults to JPEG and Small. - Pick the desired size for the resulting image under Image Size:.
It resizes: Note that the Mac will resize the image to (at most) the following dimensions:
Large: 1280 × 1280 pixels
Medium: 640 × 640 pixels
Small: 320 × 320 pixels. - Click Convert to <Image Format>.
Name change: If you convert only one image, the resulting file’s name will be selected for you to edit.
Add the “Convert Image” Quick Action to Mac Finder
To have Mac Finder offer image conversion as a choice for Finder quick actions:
- Open System Settings on the Mac.
- Go to the Privacy & Security category.
- Choose Extensions under Others.
- Now select Finder.
- Enable Convert Image.
- Click Done.
How to Convert Images on a Mac (to JPG, PNG, GIF, PDF…): FAQ
Can I convert images in bulk with Preview?
Yes.
To convert multiple images in one go with macOS Preview:
- Open the images you want to convert in a single Preview window.
- Select View | Contact Sheet from the menu.
Preview keyboard shortcut: You can also press Command Option 6.
Sidebar: Selecting images in the sidebar is also possible; select View | Thumbnails from the menu or press Command Option 2. - Highlight all the images you want to convert in the sidebar or contact sheet.
- Select File | Export Images… from the menu.
- Continue exporting the images to the desired folder. (See above.)
No visible options: If you do not see exporting options (to choose the file format, for instance), click Show Options.
File names: Preview will use the original file names with the export format’s file extension.
(How to convert an image on a Mac tested with macOS Sonoma 14.2–14.6 and Ventura 13.1; first published February 2023, last updated August 2024)