A Practical Guide on How to Compress Photos on Mac

Using Your Mac's Built-In Tools for Simple Compression

Your Mac includes tools for basic photo compression. For shrinking a few images, you do not need to install new software. The built-in Preview and Photos apps are sufficient.

These options are suitable for simple, one-off tasks. They work well for sending a few photos to a friend or uploading a profile picture. They are quick and straightforward.

Compressing Individual Photos with Preview

Preview is a capable tool for manual compression. Open an image, go to File > Export, and you will find a simple set of controls. The primary controls are the "Format" dropdown and the "Quality" slider.

Changing the format from PNG to JPG means switching from lossless to lossy compression. Lossless formats like PNG retain all original pixel data, resulting in large files. Lossy formats like JPG discard data that the human eye is unlikely to notice. This can reduce file sizes by 70-90% with minimal visible change.

As you move the quality slider for a JPG, Preview provides a live estimate of the resulting file size. This feedback helps you find the right balance between file size and image clarity.

Managing Compression in the Photos App

If you organize images in the Photos app, exporting from there is the most direct method. This is useful for sharing a small batch of photos.

Select your photos, then navigate to File > Export > Export [X] Photos. A dialog box will appear with several options.

• Photo Kind — Choose JPG for the best compression. Select PNG only if you need to preserve transparency, such as for a logo.
• Quality — Presets include Low, Medium, High, and Maximum. For web or email use, "Medium" or "High" is usually sufficient.
• Size — You can also resize the image dimensions here. Setting a custom maximum width or height is another effective way to reduce file size.

The trade-off with these built-in tools is control versus convenience. They offer free, easy compression but are not designed for processing hundreds of images at once. For bulk operations, a more specialized workflow is required.

Automating Compression with macOS Tools

Processing images one by one is feasible for small numbers. For dozens or hundreds, manual compression becomes inefficient. Automating the process is more practical, and your Mac has two built-in tools for this: the Shortcuts app and the Terminal.

The purpose of these methods is to create a workflow once and reuse it. You can run it on an entire folder of images with a single click or command. This is ideal for preparing website assets or managing a large photo library.

Building a Quick Action with the Shortcuts App

The Shortcuts app allows you to create simple automations integrated into macOS. A "Quick Action" is a custom tool that appears in the right-click context menu in Finder. This puts your compression workflow just a click away.

You can create a Shortcut that automates the following steps:

• Input — Takes any image selected in Finder.
• Resize — Resizes it to a maximum width of 1600 pixels.
• Convert — Converts the resized image into a high-quality JPG.
• Save — Saves the resulting file into a new "Compressed" folder.

Shortcuts uses a visual, drag-and-drop interface, so coding knowledge is not required. It offers more power than manual methods without the complexity of the Terminal. This type of automation is a key part of batch image processing.

Spending ten minutes to set up a compression Shortcut is a good investment. It can save hours of repetitive work over time.

Using the Terminal for Advanced Control

For developers or command-line users, the Terminal provides the most powerful way to automate image compression. It uses a built-in tool called sips (scriptable image processing system). No installation is necessary.

While it has a learning curve, sips offers significant power and flexibility for scripting. You can perform complex operations with a single line of code.

The main strength of sips is in chaining commands to process entire directory structures. However, it provides no visual feedback and has no undo function. Precision is required, but it is a highly effective tool for those comfortable with the command line.

Secure Web Tools for Enhanced Performance

Built-in macOS tools are not always sufficient. They can be inefficient for large batches or modern file formats. A secure, web-based compressor can provide more power without requiring software installation.

These tools operate in your browser, offering broad format support and high performance. A service like Compress.FAST can process 50-1000 files per batch depending on your plan. This is useful for photographers and designers working with diverse file types, including JPG, PNG, HEIC, WebP, and various camera RAW formats.

The process is straightforward: drag your files into the browser window, and the service's servers handle the compression. With a p50 (median) processing time under 200 milliseconds per image, this is often faster than using a desktop application.

Privacy and Security Considerations

Uploading files to a web service raises valid security questions. It is important to choose a service with transparent privacy practices. A trustworthy tool should process files on secure servers, preferably in a region with strong data protection laws, such as the EU.

These measures ensure your images are handled securely. You can read more about our approach to secure, encrypted processing.

Understanding Metadata Handling

Image metadata includes camera settings (EXIF), location (GPS), keywords, and descriptions. Whether this data matters depends on your use case.

For privacy and maximum compression, many web tools—including Compress.FAST—strip metadata by default. This removes potentially sensitive location data and reduces file size further. If you need to preserve metadata for professional workflows (like SEO keywords or photo library organization), macOS built-in tools like Preview and Photos typically keep this data intact.

You can learn more about how metadata is handled in our guide on metadata handling.

The primary limitation of web-based tools is the need for an internet connection. For users who need to process large, mixed batches of files quickly and securely, they remain a practical choice.

Dedicated Desktop Compression Apps

While online tools are convenient, dedicated desktop apps offer another option. They provide more power than Preview without the command-line interface of the Terminal.

These applications specialize in shrinking image files. They often use advanced lossy and lossless algorithms to remove unnecessary data, achieving file size reductions of 50-85% with no visible quality degradation.

Why Professionals Use Them

These apps integrate well into high-volume workflows and are valued by many creative professionals.

• Drag-and-Drop Batching — Process an entire folder of images by dragging it onto the app icon.
• Fine-Grained Control — Many apps allow you to select specific compression engines to balance file size and processing speed.
• RAW File Support — Photographers can often process RAW files (like NEF, CR2, or ARW) directly within the app.

Using a dedicated app keeps your entire workflow on your local machine. This is a significant advantage for sensitive client work or when working with an unstable internet connection.

Real-World Performance

For designers and developers, a third-party compression tool can improve productivity. It is common for these macOS utilities to reduce JPG and PNG sizes by 50-85% by removing unneeded metadata and applying more efficient compression.

For instance, one Mac-only compressor on the App Store processes approximately 7,200 images per day, or about five images per minute, using simple drag-and-drop batching. You can explore these powerful Mac compression utilities on the App Store to see available options.

The main downside is the need to manage the software, including updates. For users who regularly compress photos and require this level of control, the convenience and power of an offline tool often outweigh this minor responsibility.

Choosing the Right Compression Method for Your Task

The best method to compress photos on your Mac depends on your specific goal. There is no single correct tool; the right choice balances speed, control, and quality for the job at hand.

For a simple, one-time task, such as emailing a few photos, the built-in Preview app is sufficient. Open the image, select 'Export,' and use the quality slider. It is fast, free, and pre-installed.

Matching the Tool to the Workflow

For more complex needs, you must weigh the pros and cons of each approach. A developer preparing 100 product images for an e-commerce site needs a repeatable, efficient workflow that preserves SEO metadata. Manual processing is not practical in this scenario.

• Small, infrequent batches (1-10 photos) — Use Preview or the Photos app. They require no setup and handle basic JPG or PNG exports.
• Repetitive, large batches — An automated Shortcut or a Terminal sips script will save significant time in the long run.
• Mixed formats and high security — A secure web tool like Compress.FAST offers the best format support for projects involving HEIC, RAW, and JPG files.
• Offline power and control — A dedicated desktop app like ImageOptim provides a powerful offline workflow with granular settings.

First, identify your primary goal. Are you optimizing for speed, maximum compression, format compatibility, or batch processing? The answer will guide you to the appropriate tool.

Feature Comparison of Mac Compression Methods

This table compares these methods to help you choose the right tool based on your needs for speed, format support, security, and ease of use.

If you need more detail, you can learn more about how to reduce picture megabytes and find the optimal balance between file size and quality.

Knowing how to compress photos on a Mac is about understanding the available options and choosing the right one for each task.

Frequently Asked Questions

Here are direct answers to common questions about compressing photos on a Mac.