What is a ZIP File?

A file with the ZIP file extension is a ZIP Compressed file and is the most widely used archive format you'll run into.

A ZIP file, like other archive file formats, is simply a collection of one or more files and/or folders but is compressed into a single file for easy transportation and compression.

The most common use for ZIP files is for software downloads. Zipping a software program saves storage space on the server, decreases the time it takes for you to download it to your computer, and keeps the hundreds or thousands of files nicely organized in the single ZIP file.

How To Open a ZIP File

The easiest way to open a ZIP file is to just double-click on it and let your computer show you the folders and files contained inside. In most operating systems, including Windows and Mac OS, ZIP files are handled internally, without the need for any extra software.

However, there are many compression/decompression tools that can be used to open (and create!) ZIP files. There's a reason they're commonly referred to as zip/unzip tools! 

Including Windows, just about all programs that unzip ZIP files also have the ability to zip them - in other words, they can compress one or more files into the ZIP format. Some can also encrypt and password protect them. If I had to recommend one or two, it'd be PeaZip or 7-Zip, both excellent and completely free programs that support the ZIP format.

If you'd rather not use a program to open a ZIP file, there are lots of online services that support the format, too.

Online services like WOBZIP, Files2Zip.com, and B1 Online Archiver let you simply upload your ZIP file to see all the files inside, and then download one or more of them individually.

Note: I recommend using an online ZIP opener only if the ZIP file is on the small side. Uploading a large ZIP file and managing it online will probably take you more time and energy than just downloading and installing an offline tool like 7-Zip.

You can also open a ZIP file on most mobile devices. iOS users can install iZip for free, and Android users should be able to work with ZIP files via B1 Archiver or 7Zipper.

Tip: If you need help opening a .ZIP.CPGZ file, see What is a CPGZ File?.

How To Convert a ZIP File

Files can only be converted to something of a similar format. For example, you can't convert an image file like JPG into an MP4 video file, any more than you can convert a ZIP file to PDF or MP3.

If this is confusing, remember that ZIP files are just containers which hold compressed versions of the actual file(s) you're after. So if there are files inside a ZIP file that you want to convert - like for a PDF to DOCX or MP3 to AC3 - you must first extract the files out using one of the methods described in the section above, and then convert those extracted files with a file converter.

Since ZIP is an archive format, you can easily convert ZIP to RAR, 7Z, ISO, TGZ, TAR, or any other compressed file, in two ways, depending on size:

If the ZIP file is small, I highly recommend using the Convert.Files or Online-Convert.com free online ZIP converter. These work just like the online ZIP openers from above, which means you'll need to upload the whole ZIP to the website before it can be converted.

To convert larger ZIP files that would take much longer to upload to a website, you can use Zip2ISO to convert ZIP to ISO or IZarc to convert ZIP to lots of different archive formats.

If none of those methods work, try one of these Free File Converters for Occasionally Used Formats to convert the ZIP file to another file format. The one I particularly like is Zamzar, which can convert ZIP to 7Z, TAR.BZ2, YZ1, and other archive formats.

More Information on ZIP Files

If you've password protected a ZIP file but then forgot the password, you can use a password cracker to remove it to regain access to your files.

One free program that uses brute force to remove a ZIP password is ZIP Password Cracker Pro.

Some ZIP files may have a file name with a different file extension before the final "zip" extension. Just keep in mind, like with any type of file, it's always the very last extension that defines what the file is.

For example, Photos.jpg.zip is still a ZIP file because JPG comes before ZIP. In this example, the archive is probably named this way so it's quick and easy to identify that there are JPG images inside the archive.

A ZIP file can be as small as 22 bytes and as large as around 4 GB. This 4 GB limit applies to both the compressed and uncompressed size of any file inside the archive, as well as to the total size of the ZIP file.

ZIP's creator Phil Katz' PKWARE, Inc. has introduced a new ZIP format called ZIP64 that raises the size limitation to 16 EiB (around 18 million TB). See the ZIP File Format Specification for more details.