Zip vs compress: which one do you need?
Zipping (Finder's Compress or Windows' Compressed (zipped) folder) uses lossless compression. It's ideal for sending a folder of documents as one file, and text-heavy files shrink a lot. But JPEG photos, PDFs with images and videos are already compressed, so zipping them typically saves only 0–5%.
Compressing an image or PDF re-encodes it: photos are saved at a lower quality, PDF images are resampled. That's what turns a 6 MB photo into 1.5 MB or a 30 MB scanned PDF into 4 MB.
How to zip files on a Mac
- Select the files or folder in Finder.
- Right-click (or Control-click) and choose Compress.
- macOS creates Archive.zip (or FolderName.zip) next to the originals.
To unzip, double-click the .zip file. The originals are left untouched.
How to make a PDF or image smaller on a Mac
PDF: open it in Preview, choose File → Export, and pick Reduce File Size from the Quartz Filter menu. It's fast, but the filter is aggressive and can make images and scanned text blurry, with no quality control.
Images: in Preview, use Tools → Adjust Size to reduce the pixel dimensions, or File → Export and lower the quality slider for JPEG and HEIC. Converting iPhone HEIC photos to JPEG is covered in our HEIC to JPEG guide.
How to zip files on Windows
- Select the files or folder in File Explorer.
- Right-click and choose Send to → Compressed (zipped) folder (on Windows 11, it's Compress to ZIP file, or under Show more options).
- Windows creates a .zip file next to the originals.
Windows 11 can also create 7z and TAR archives from the same menu. To unzip, right-click the archive and choose Extract All.
How to make a PDF or image smaller on Windows
Windows has no built-in PDF compressor — Microsoft Print to PDF doesn't reduce image resolution, so it rarely makes a PDF smaller.
For images, the Photos app can resize a picture (… → Resize image) and choose a smaller size or quality, and Paint can resize and save as JPEG. Both handle one image at a time.
The same on any computer: compress in the browser
If you want quality control, batches and PDFs on both systems, a browser tool is simpler. MiniFiles runs in Chrome, Safari, Edge and Firefox on Mac and Windows, and compresses files on your computer — nothing is uploaded.
- Images: the image compressor shrinks JPG, PNG, WebP and GIF files in batches with a quality slider; Compress PNG, Compress JPEG and Compress GIF are tuned for each format.
- PDFs: Compress PDF recompresses the images inside a PDF while keeping text sharp, with dedicated tools to get under 1 MB or 100 KB.
- Other PDF tasks: merge, split and password-protect PDFs locally.
It's free, with no installation and no account needed for up to 10 files a day.
Which method should you use?
- Sending a folder of documents: zip it with Finder or File Explorer.
- Making photos smaller for email or upload: compress them as JPEG or WebP — see how to reduce file size for email.
- Shrinking a video: compress it to 720p, or convert iPhone MOV to MP4.
- Shrinking a PDF: use a PDF compressor; Preview's filter works in a pinch on Mac but offers no control.
- Confidential files: avoid upload-based websites and compress locally.