How to convert any file to any format

A file's format—the way that it's saved and encoded—determines what you can do with it and which programs can open it. (You can check its format by looking at the file name's extension.) Think of each format like a different language, with some only understood by specific platforms and applications. To access any given file, you may need to convert it to a new format.

For example, something your colleague created on a macOS word processor might not work on your Windows 10 computer. Or a website that asks you to upload a photo might insist that it be a specific type of file. Whatever quandary you encounter, you can usually hunt down an app to help. In this guide, we'll recommend some of the best format-conversion services out there, and give you a few tips so that you never get stuck with a wrongly-encoded file.
First step: check your applications
Frequently, the application you used to create the file in the first place will let you save it as something else. If you're viewing a document in Google Docs, for example, then you can click File and Download as... to bring up a list of formats to which you can convert the page. These include Microsoft Word, PDF, plain text, and others. The desktop programs Word and Pages offer a similar selection of formats.
As with word processors, so with image editing programs: Most of these applications let you save your pictures as a variety of file types, so you can pick the appropriate one. Export an image from Photos on macOS, for example, via File and Export. It will let you choose between JPEG, PNG, and TIFF formats.
If you know that you'll want to access a given file using multiple programs, you can save the file in several formats to begin with. Of course, you won't always have access to the program that originally created the file. In that case, you'll want to use a conversion program. The program you choose will depend on the type of file you're tinkering with.

For videos
For your video conversion needs, you can't go wrong with the free programs Handbrake and VLC. Handbrake (for Windows, macOS, and Linux) takes video files from almost every imaginable format and converts them into any other popular video type. It's simple to operate, and even lets you pick from standard pre-set modes in order to, say, optimize the videos you're converting for an iPhone X. When you're more comfortable with the software, you can also dig deeper into the settings for the codecs—the exact standards by which the video files are saved. Beyond that, Handbrake rips videos from DVDs and supports subtitles and chapter markers in your conversions.
Equally impressive, VLC Media Player (for Windows, macOS, and Linux) can it play a whole host of video formats, including MPEG-4, H.264, WMV, and MKV, with no extra plug-ins. It can also convert between a broad selection of different file types. Think of it as a Swiss Army Knife for video conversions. With the program open on screen, choose Media then Convert/Save. The application asks you to pick a video file from the hard drive, and you can then choose the format you want to change it into. Rather than writing over the original file, VLC will create a separate copy of the newly-reformatted video. You can include subtitles and chapter markers in the conversion, and even convert batches of files at once.

For images
You can find even more free programs to convert your photos, so we've selected our top three picks. XnConvert (for Windows, macOS, and Linux) lets you resize pictures, change the color depth, and even add text as you're converting your photos. And if you're in a hurry, you can convert whole batches of images at once.
As impressive as XnConvert, Adapter (for Windows and macOS) is also a little more user-friendly. To get started, drag files on top of the application interface, choose your output for format and click the Convert button. Along the way, you can change the resolution and quality of the file. Adapter is happy converting a long list of files in one go. On top of images, it converts between popular video and audio file formats as well.
If you prefer something that requires no installation and can be run from inside any web browser, then give the versatile Zamzar a try. It supports conversions to and from over 1,200 different file types, including pictures, video, and audio. The only downside is that you'll have to pony up your email address in order to use the service: Once it converts a file, it sends a link to the address you provided.

For audio
Some of the applications we've mentioned above, like Zamzar and Adapter, also tackle audio files. If you want a dedicated audio converter, however, you can find plenty of other programs.
The free free :ac (for Windows, macOS, and Linux) supports a wide variety of formats from FLAC to MP3. In addition, you get several different options that let you tinker with the audio quality. Load up your tracks using the Add audio files button on the top left, then choose your output format on the General settings part of the Options menu. To set the output options in more detail, select Options and Configure selected encoder. Once you're happy with the settings, click the green play button on the toolbar to start the conversion (encoding) process.
The simple and straightforward Free Audio Converter from Freemake (for Windows only) is another good choice. With this application, you just drag your audio into the program window, choose your output format from the list at the bottom, and you're good to go. It supports common audio formats such as MP3, AAC, WMA, OGG, and FLAC.

Finally, if you want to take more control over the audio as you convert it, then opt for the free audio editor Audacity (for Windows, macOS, and Linux). In addition to a full suite of editing tools, it gives you the option to convert your files between various popular formats. To do so, open the track in question, hit the File menu, and head to the Export option.
For documents
Compared with music and movie files, documents seem relatively simple. But converting between document formats can be trickier, because many of them—the Word document format from Microsoft, the Pages document format from Apple, and so on—are proprietary.
Because of its finicky format, you should, wherever possible, try using a document's native program to open it and convert it to something else. If you don't have the right software to do so, consider falling back on a web app. You can access basic versions of both Microsoft Office and Apple iWork online, allowing you to use them from any browser for free.