If you work with your Mac daily, you'll know that the files are getting bigger and biggerPDFs packed with images, 4K videos, huge photos, documents full of graphics… and, of course, storage fills up, the system slows down, and problems arise when sending emails or uploading to the cloud. The good news is that macOS has a ton of tools to reduce the size of almost any file, and there are also specific apps that help you go a step further without losing quality.
In this guide you will learn How to compress files on Mac without sacrificing quality We'll focus on what really matters: legible text, crisp photos, and high-quality videos. We'll explore built-in methods (Finder, Preview, QuickTime, Archive Utility), advanced options, and some extra tips to help you decide whether compression, optimization, or simply not compressing at all and opting for cloud transfer is worthwhile in each situation.
Why do the files weigh so much (and what does “without losing quality” mean)
Before we start compressing like crazy, it's worth understanding What makes a file take up so much space? And what can we do without it being visually noticeable (or almost). Several factors influence a PDF, an image, or a video.
In PDF documents, the file size skyrockets mainly because high-resolution images and uncompressed scansIf you scan a document in high quality and save it as a PDF, you are actually putting one or more giant photos inside the file, which increases the megabytes.
PDFs also take up more space than they should. They embed many fonts, hidden layers, or metadata that don't contribute anything to the content (for example, internal information from design programs or editing data that just sits there "hanging"). All of that can be optimized without the user noticing a dramatic change.
In images and photos, the size depends on the resolution (in pixels) and the type of compressionFormats like JPEG or WebP allow for significant compression while maintaining reasonable quality, but if you save everything in giant PNGs without thinking, the file size skyrockets.
In video, size is the main factor. the resolution (4K, 1080p, 720p), the bitrate, and the codecAn uncompressed or overly high-quality 4K video is usually a monster in size. Reducing the resolution or bitrate, or using more efficient codecs, significantly lowers the file size at the expense of some quality… the trick is finding the right balance.
When we talk about compressing “without losing quality” in the strictest sense, we mean lossless compressionwhere, upon decompression, you can reconstruct the original file exactly (as is the case with many ZIP files). But in practice, when people search for "without loss of quality," they usually mean "without it being noticeable to the naked eye," even if there is technically a slight loss.
Reduce the size of a PDF on Mac using Preview
If PDFs are your biggest concern, you're in luck: macOS includes the Preview app by default.which not only serves to view documents and images, but also to compress PDFs in a matter of seconds.
To reduce the size of a PDF using Preview, the basic process is very simple: You open the document, export it with a compression filter, and save a lighter copy.There's no need to install anything additional; everything is integrated into the system.
The standard workflow would look something like this: you open the PDF with Preview, go to the File menu, and choose the export option. Within that dialog box, macOS offers what are called... “Quartz Filters”Among the options you'll find is "Reduce file size". Applying this filter and saving will generate a new, smaller PDF.
In some systems you can also find options for optimize images for screenThis further reduces the size by lowering the resolution to something sufficient for viewing on a computer, tablet or mobile, but not enough for professional printing.
The main advantage of this method is that it is Fast, free, and fully nativeYou don't install anything and in two clicks you have the PDF ready to send by email or upload to a platform.
The downside is that, according to the content, It can significantly reduce image qualityEspecially if the PDF is full of photos or complex graphics. For mostly text documents, it's usually perfect; for catalogs, visual dossiers, or comics, you might want something more refined.
As a rough guide, in many cases you can achieve reductions of this order using Preview and similar settings:
• Text-only PDFs: approximate reduction of 60-80% of the original size.
• Scanned PDFs: 70-90% reduction if the resolution is lowered and the image is compressed well.
• PDFs with many images: They usually drop around 40-70% while maintaining acceptable screen quality.
If you need much more precise control (choosing exact image resolution, quality, which metadata to keep, etc.), you can use professional tools such as Adobe Acrobat Pro or PDF Expertwhich allow you to adjust many more parameters and achieve a visually very clean compression.
Other ways to optimize PDFs and documents on Mac
Besides Preview, there are other moments in the workflow where you can Reduce the size of your documents even before creating the PDF, which helps ensure that the final files are already optimized.
For example, if you're exporting from editing or layout programs, it's usually useful. Remove unnecessary pages and imagesAvoid including photos at absurd resolutions or activating options like "Optimize for web" when generating the PDF.
In the specific case of text documents created in Microsoft Word or Pages, you can compress the file from within the editor itselfWord for Mac, for example, includes a "Reduce file size" or similar function, which acts on embedded images.
The operation is usually based on a dialog box where you choose the desired image quality (e.g., for screen or for printing) And you can select options like "Remove cropped areas from images" to erase hidden parts that only take up space without contributing anything.
By applying those settings and saving, you get a much lighter resulting Word file or PDFIdeal if you're going to share it by email or store it on a disk with limited space.
Compress images on Mac without them looking bad
Photos are one of the biggest culprits behind the "Disk Almost Full" sign. On a Mac, you have two main ways to... reducir el tamaño de las images: use built-in tools (Preview, Photos) or rely on specialized software.
With Preview, you can open an image (or several) and use the Tools menu to adjust the size in pixels, percentage, etc.If you reduce the image dimensions (for example, from 6000 px wide to 2000 px), the file size decreases significantly without it looking terrible on screen.
In addition to the resolution, you can also change the output formatSaving a photo in JPEG or WebP with a reasonable level of compression can greatly reduce the size compared to a gigantic PNG, while maintaining more than enough visual quality for networks, web or presentations.
If you often work with many images at once and want something more powerful, there are tools like Wondershare UniConverterwhich allow you to compress and convert images in batches with considerable control over file size and perceived quality.
These types of programs usually offer options for upload a bunch of photos at once, choose a specific output size, and adjust a quality sliderAs you swipe, the software calculates the estimated size of the result, allowing you to find a balance between low megabytes and good appearance.
The great advantage of these solutions is that They automate the compression of large volumes of images (for example, an entire photo shoot or materials for a website) without having to go one by one, which saves a lot of time.
Reducing video size on Mac (and when it's not a good idea to compress)
When we talk about video, the numbers skyrocket: a couple of 4K clips can devour the available space on your Mac in no timeHere again, you have two great options: compress the file or not compress it and opt to share it in the cloud.
If you decide to compress, you can use specialized tools such as UniConverterwhich include a video compressor with support for almost any format. They usually allow you to choose an approximate final size, reduce the resolution or bitrate, and also compress multiple videos at once.
The typical workflow in this type of app involves starting the program, choosing the compression section, Add the videos you want to reduce. and apply an output profile or a custom configuration. After pressing the start button, the software processes the files and delivers much lighter versions.
macOS also includes a built-in solution for simple cases: QuickTime PlayerApple's video player allows you to export a video at different resolutions, such as 1080p, 720p, or 480p. Lowering the resolution significantly reduces the file size.
The downside of QuickTime is that fine-tuning over bitrate and other parameters is limited, and Quality may suffer if you make very aggressive reductions.Even so, for quickly reducing the size of a home video or a clip to send by email, it's usually sufficient.
Now, there's a key point: if what worries you is Share a large video without losing any quality whatsoeverPerhaps the best "compression" is not to compress at all. In these cases, it makes more sense to use cloud file transfer services.
With large file transfer platforms (for example, Smash-type solutions and similar), you can Upload the original video from your Mac and share it via a link.The other person downloads it exactly as it is, with the same resolution and quality that you see on your computer.
This approach has several advantages: you don't lose any video or audio quality, you avoid having to wait twice (once to compress and again to upload), and in many cases the services are free even with very large filesIf the goal is to preserve the highest quality, it's a very worthwhile option to consider.
Compress files and folders in macOS with Finder
Beyond PDFs, images, or videos, one of the most common uses in everyday life is compress folders or loose files into a ZIP file to save space or send a complete "package". On Mac, this is done directly from the Finder, without any extra applications.
The process is very straightforward: you locate the file or folder you want to compress in the Finder, you do Right-click (or Control + click) Select it and choose the "Compress" option. If you select multiple items at once and then choose "Compress X items", the system will combine them into a single ZIP file.
The generated ZIP file appears in the same location as the originals. If you have only compressed one elementIt will retain the same name by adding the extension “.zip”. If you group several, macOS usually creates a file named something like “Archive.zip”.
After creating the ZIP file, it's a good idea rename it to identify it Better yet: right-click on the ZIP file, select "Rename," type the new name, and you're done. You can also drag the ZIP file to a specific folder to keep all your compressed files organized, or even add that folder to Favorites in Finder for easy access.
Compressing to ZIP from Finder uses a generic compression type that It doesn't offer many advanced options (You don't choose the compression level, method type, etc.), but it's more than enough for everyday use: grouping project documents, sending a folder of photos, sharing code, or packaging files for a quick backup.
Unzip ZIP and other compressed files on Mac
Decompressing on macOS is even easier than compressing. When you do double-click on a .zip fileThe system will automatically use its built-in utility to expand the content in the same folder.
After extraction, you'll see the resulting folder or file alongside the original ZIP. If you wish, you can delete the .zip file to avoid having it duplicated and taking up unnecessary space; the uncompressed content will not be affected.
The system is also capable of handling other formats through the Archive Utility (File Utility), which opens in the background to do the job. By default, you don't need to touch anything: macOS takes care of opening the compressed file transparently for you.
In some workflows, you can also choose "Open with" and manually select the file utility from the context menu, just in case. You want to make sure that this is the tool that does the decompression. and not another third-party app that you have installed.
In Windows systems, there is also the possibility of drag files into an existing ZIP to add new contentOn macOS, however, this doesn't work the same way: if you want to include new files in a ZIP, you usually have to create a new one or use a third-party application with more advanced features.
Use Archive Utility and third-party apps for more advanced compression
Beneath what you see in Finder, macOS uses a tool called Archive Utility to manage the creation and expansion of compressed files. Although it usually works in the background, you can also open it directly.
By running Archive Utility and accessing its File menu, you can create compressed files from a custom interfaceInstead of right-clicking in the Finder. This is useful if you want to centralize the task in one place or adjust a particular utility preference.
If the native options fall short, you have third-party apps at your disposal such as cakeKeka, very popular on macOS, facilitates the compression and decompression of files and folders in multiple formats: 7z, ZIP, Tar, Gzip, and others.
Its typical use consists of installing the application (from the official website or the Mac App Store), opening it and drag the files or folders you want to compress into the folder.Then you choose the output format and compression parameters (level, splitting into parts, password, etc.).
With Keka and similar tools you can to adjust in much greater detail the relationship between size and compression speedFor example, it is possible to use stronger compressions (slower but with smaller files) or formats with a better compression ratio than classic ZIP, such as 7z.
In Windows, many users are accustomed to finding an option called "Compression Method" in compression tools, with levels such as "Store," "Fastest," "Fast," "Normal," etc. In macOS, the built-in utility It does not offer that same range of visible levels as standard.If you need something equivalent (for example, the "Store" method, which basically packages uncompressed for maximum speed), the usual thing is to resort to advanced apps like Keka or command-line solutions.
Optimize space on your Mac: clean, compress, and use the cloud
Compressing files helps a lot, but it's not the only card you have to play. Keep your Mac fast and with free spaceIdeally, you should combine several simple strategies that, together, make a difference.
One of the most effective is to check periodically files and applications you no longer needThe Downloads folder is often full of old installers, duplicates, and documents you only needed once. Deleting them frees up a lot of space in no time.
Another important advantage is to take advantage iCloud and other cloud servicesBy moving old documents, photos, and projects to the cloud, you free up local space without losing access to the content, which will remain available on all your Apple devices.
You can also gain space by cleaning cache files, logs, and app remnants that the system accumulates over time. There are specific tools (like the typical macOS cleaning utilities) that help get rid of these junk files safely.
File and folder compression fits into this overall strategy as a bonus to make the most of the storage you already haveBy packaging projects you don't use daily or that you just want to archive, you keep them accessible, but they take up less space.
The key is to combine well: clean up what's unnecessary, move to the cloud what you want to keep long-term, and Compress whatever you need to group or reduce in size maintaining an acceptable quality for your use.
In short, if you understand why your files are the size they are and what tools macOS offers to reduce their size, you have almost everything you need to Compress files on your Mac without apparent loss of qualityKeep your team agile and share any type of content without stress, choosing in each case whether a lightweight ZIP, internal file optimization, or a direct cloud transfer without touching a single bit of quality suits you best.
