The fastest way depends on what kind of file you have
The method that works best depends on whether you're compressing a photo, a video, a document, or a folder full of mixed files. Photos and videos shrink most when you reduce their dimensions or quality — a process called lossy compression because you lose detail you can't get back. Documents and spreadsheets compress better with lossless compression, which squeezes the file without throwing away information. For multiple files at once, creating a ZIP archive bundles them together and compresses them in one step.
Start by checking how large your file actually is. Right-click the file on Windows and select Properties; on Mac, right-click and choose Get Info. If it's under 25 MB, most email services and cloud storage will take it as-is. If it's larger, or if you're hitting a specific upload limit, one of the methods below will get you there.
Key Takeaways
- Photos shrink fastest by opening them in Preview (Mac) or Photos (Windows) and exporting at a lower resolution or quality setting.
- Videos need a video editor or free tool like HandBrake to reduce resolution or bitrate without losing the entire file to compression artifacts.
- Documents and PDFs compress best with a ZIP archive, which you create by right-clicking the file and selecting "Send to > Compressed folder" (Windows) or "Compress" (Mac).
- Multiple files of different types should go into a single ZIP archive rather than compressed individually, because the archive compresses the whole batch together.
- Online compression tools work but upload your file to someone else's server, so avoid them for sensitive documents or use only services with published privacy policies.
Compressing photos without losing too much quality
Open the photo in your system's built-in image viewer. On Mac, use Preview: open the photo, go to Tools > Adjust Size, and lower the width and height (keep the lock icon clicked so the proportions stay the same). Then go to File > Export, choose JPEG format, and drag the Quality slider to 75 or 80 percent. That usually cuts file size in half with almost no visible difference.
On Windows, open the photo in the Photos app, click the three dots at the top right, select Edit, then choose Crop & Rotate. After you're done editing, click Save a Copy, and Windows will prompt you to choose a quality level. Select Medium or Low depending on how much smaller you need it to be.
If you have many photos, batch processing is faster. On Mac, you can use Automator (built into macOS) to resize and export a whole folder at once. On Windows, free tools like ImageMagick or XnConvert let you set one quality level and apply it to dozens of files in minutes. For a single photo that needs to be much smaller, reducing the width and height to 50 percent of the original usually cuts the file size to a quarter of what it was.
Reducing video file size
Videos are large because they contain thousands of still images played in sequence. Shrinking them means either playing them at a lower resolution (720p instead of 1080p, for example) or reducing the bitrate, which is how much data the video uses per second. Both methods take time to process — usually several minutes for a short video.
The free tool HandBrake works on Windows, Mac, and Linux. Download it, open your video file, and in the Presets panel on the right, choose a lower resolution preset like "Fast 720p30" or "Fast 480p30". Click Start, and HandBrake will re-encode the video at that resolution. A five-minute video at 1080p might shrink from 500 MB to 100 MB at 480p, though the picture will be noticeably smaller on a large screen.
If you need the video to stay at its original resolution but just be smaller, look for the Bitrate setting in HandBrake (under the Video tab) and lower it from the default. Bitrate is measured in kilobits per second (Kbps); lowering it from 5000 to 2500 Kbps will cut the file roughly in half but may introduce visible compression artifacts, especially in fast-moving scenes.
Creating a ZIP archive for documents and mixed files
A ZIP archive is a single file that holds other files inside it and compresses them automatically. It's the standard way to send multiple files at once and works on every operating system. On Windows, right-click the file or folder you want to compress, hover over Send To, and click Compressed (Zipped) Folder. Windows creates a new .zip file in the same location.
On Mac, right-click the file or folder and select Compress. A .zip file appears next to the original. For a folder with many files, this single step often reduces the total size by 20 to 40 percent, depending on what's inside. PDFs, Word documents, and spreadsheets compress well this way because they're already partially compressed internally.
If you're sending the ZIP file to someone else, they can open it on any computer without installing anything — Windows, Mac, and Linux all have built-in ZIP support. If the ZIP file is still too large for your upload limit, you'll need to use one of the other methods above (reduce photo resolution, lower video bitrate) before creating the archive.
Using online compression tools safely
Websites like TinyPNG, Compress.com, and CloudConvert let you upload a file, compress it, and download the result without installing software. They're convenient for a single file, but they upload your file to someone else's server, which means you're trusting that company with your data.
If you use an online tool, check whether the site has a published privacy policy and whether it deletes files after a set time (most delete after a few hours, but verify). Avoid uploading sensitive documents, financial records, or anything with personal information unless you're certain the service is secure. For everyday photos and videos, most major compression sites are safe, but doing the compression yourself on your own computer is always the more private option.
Some online tools offer batch processing, which is useful if you have dozens of photos to shrink at once. Upload a folder, set the quality level, and the tool compresses everything and gives you a ZIP file to download. This is faster than doing each photo individually on your computer, but again, your files are temporarily on their server.
When to use each method
| File Type | Best Method | Expected Size Reduction |
|---|---|---|
| Single photo | Reduce resolution and quality in Preview or Photos | 50–75% |
| Multiple photos | Batch resize with Automator or XnConvert, then ZIP | 60–80% |
| Video | HandBrake at lower resolution or bitrate | 50–90% |
| Documents or PDFs | ZIP archive | 10–40% |
| Mixed files (photos, docs, videos) | Compress photos and videos first, then ZIP everything | Varies |
Frequently Asked Questions
Will compressing a photo make it look bad?
At 75–80% quality, most people can't see a difference on a screen. If you're printing the photo or displaying it large, you might notice some softness or color banding. For email or social media, 70% quality is usually fine. The lower you go, the more visible the loss becomes — below 60% you'll start to see obvious artifacts.
Can I compress a file that's already been compressed?
Yes, but you won't save much. A JPEG photo is already compressed, so putting it in a ZIP archive might only shrink it another 5–10%. Videos are heavily compressed too, so re-compressing them with HandBrake works, but you're starting from an already-squeezed file. Documents compress better a second time because they're not as tightly compressed to begin with.
What's the difference between ZIP and RAR or 7Z?
ZIP is the standard and works everywhere without extra software. RAR and 7Z compress slightly better but require the recipient to install software to open them. For sharing files, ZIP is almost always the right choice. Use RAR or 7Z only if you need maximum compression and the person receiving the file has the software already.
If I compress a video with HandBrake, can I undo it and get the original quality back?
No. Once you re-encode a video at a lower resolution or bitrate, that information is gone. Always keep the original file before you compress. If you only have the compressed version and later need higher quality, you'll have to re-shoot or find the original source.
Why is my ZIP file almost as large as the original?
Some files don't compress well. Videos, photos in JPEG format, and music files are already compressed, so putting them in a ZIP saves only a few percent. Documents, spreadsheets, and text files compress much better. If your ZIP is barely smaller, the files inside are probably already in a compressed format.