How to Compress Files at a High Level Using 7zip

This article provides a guide on how to achieve the smallest possible ZIP file size using a Windows or Mac computer. While the default file compression tools on Windows and macOS work fairly well, they do not offer the option for higher compression levels. Fortunately, you can use the free and easy-to-use 7-Zip app on Windows, which provides greater control over the final file size. While 7-Zip is not available on macOS, the Keka app offers similar functionality to achieve comparable results. It's important to note that files already in a compressed format, such as MP3, AVI, MPG, and JPG, will not reduce in size further when compressed into a ZIP file.

Install 7-Zip for Windows. The 7-Zip application is a free file compression tool that offers more compression options than the standard Windows compression/decompression tool. You can download the free app from https://www.7-zip.org.

• After downloading the program, simply double-click the installer and follow the on-screen instructions to install 7-Zip.

Right-click on the file or folder you wish to compress. To compress multiple files into one Zip folder, you can add them to a folder and right-click, or hold the Control key while clicking on each file, then right-click on the highlighted area.

Select 7-Zip from the menu. Several options will appear here.

Click on Add to archive… (Add to archive…). The 7-Zip program will immediately open the Add to Archive screen.

Select the archive format. The ZIP format is easily accessible on various platforms, but if you choose the 7z format, the ZIP file will have a smaller size.

• If you wish to send a 7z file to someone, they can extract it without needing additional software on a Mac. On Windows, they will need to install 7-Zip, WinZip, or any archiver compatible with the 7z format.

Choose Ultra (Ultra level) from the "Compression level" menu. This option will give you the smallest file size.

Select LZMA or LZMA2 from the "Compression method" menu. LZMA2 is the latest update of LZMA. Both options offer higher compression rates compared to others.

Set the compression volume size (optional). 7-Zip will automatically select a default compression volume based on the compression level you chose. For larger files, you can increase the volume size beyond the default 64MB to reduce the file size, but keep in mind that the compression process will take longer. The maximum volume size is 256MB.

Click OK to compress the file. Once 7-Zip finishes creating the compressed file, it will appear in the same folder as the original file – with either a .zip or .7z extension.

• To check the size of the compressed ZIP file, right-click on the .7z or .zip file and select Properties.

Install Keka. This open-source and free compression tool for macOS provides more compression options than the default zip utility. To download Keka, open the App Store on your Mac (the white "A" icon on a blue background) and search for keka. After finding the app, click the GET button to install it.

Launch Keka. Once you've installed Keka, you can find the program in Launchpad or the Applications folder on your device.

Select the compression format. To achieve the highest compression level, you should choose ZIP, 7z, or GZIP. The ZIP format is the most widely used and can be opened on any platform without the need for additional tools. However, comparison tests show that 7Z compresses files into a smaller size than other formats and does so faster.

• On Mac, you will need special software to extract 7z files, whereas Windows users can install the free 7-Zip software.

Move the slider to the right. When the slider is set to "Slow", Keka will compress the file to the smallest possible size. Since this is a high-compression process, the time required for compression will be longer, as indicated by the "Slow" setting here.

• Leave the other settings at their default values to achieve the highest compression in the shortest amount of time.

Drag the file you want to add to the compressed ZIP folder. To compress multiple files into one ZIP folder, you can add them to a folder and drag the folder into the app. Alternatively, hold down the Command key while clicking each file and drag the selected files into Keka. This will compress the files into either ZIP or 7z format, depending on your choice.

• To view the file size, click on the file in Finder, then press Command + I to see the file information.

• If you need to compress a file that is already in a compressed ZIP format, start by reducing the file size. This means trimming the audio file or lowering the resolution of the JPG file.
• Both 7-Zip and Keka allow you to split a ZIP or 7z file into smaller parts and also create larger files.