Convert Images, Audio, and Video on a Mac

Updated 9 November 2026 · Standard formula, shown below

Converting media on a Mac lets you make files smaller, change formats for compatibility, or prepare them for sharing and editing. The right method depends on the file type: macOS includes simple conversion options for many images and audio files, while video often needs a dedicated app.

What You’ll Need

A Mac with enough free storage for the original and converted files.
The file you want to convert, plus permission to use it.
For video or formats that macOS cannot open, a reputable converter that supports the format you need. Prefer software from its developer or a trusted app store.
The target format and, if relevant, the intended size, quality, or playback device.

Step-by-Step

Make a working copy. In Finder, duplicate the original before converting: select it and choose File > Duplicate, or copy it to another folder. Keep the source until you have checked the result. Some conversions discard information or reduce quality, and changing a file extension alone does not convert its contents.
Choose the destination format. Check what the receiving app, website, or device accepts. For images, JPEG is widely compatible and compact but does not preserve transparency; PNG preserves transparency and is often larger; HEIC can be compact but may not work everywhere. For audio, MP3 is widely supported and compressed, while WAV and AIFF are generally larger. For video, MP4 with H.264 is broadly compatible; newer codecs may reduce size but are not supported by every device or app.
Convert an image with Preview. Open the image in Preview. Choose File > Export, then select a format from the Format menu. If the format menu is not visible, hold Option while opening the Format menu. Choose a destination, set available options such as quality or resolution, and click Save. For multiple images, select them together in Finder and open them in Preview; use the thumbnail sidebar and select all images before choosing File > Export Selected Images, if that command is available in your macOS version. Confirm the destination and format before exporting.
Convert audio with the Music app, if supported. Open Music and choose Music > Settings (or Preferences on some versions), then Files > Import Settings. Choose an encoder such as MP3 Encoder or WAV Encoder and adjust its available quality setting. Select a track in your library, then choose File > Convert > Create [format] Version. The converted copy appears in the library. This method is intended for audio the app can access; it may not convert protected or unsupported files. To convert a file outside the library, use a trusted audio converter that explicitly supports its format.
Convert video in a compatible app. Open the video in an app that supports exporting, then look for File > Export, Share, or an equivalent export command. Choose a preset or format accepted by your destination, select a resolution and quality, and save to a new location. If the app has no export option or cannot open the source, use a reputable video converter that supports both the input and output codecs. Check the app’s settings before converting; a .mov or .mp4 filename extension does not by itself identify every codec inside the file.
Set quality and size sensibly. Keep the original dimensions and frame rate unless you have a reason to reduce them. Lower image quality, audio bitrate, or video resolution can shrink a file but may make artifacts, softness, or distortion more noticeable. For a smaller video, try a lower resolution or a more efficient codec only if your playback device supports it.
Save to a clear destination. Choose a folder you can find, such as a new folder named Converted. Give the output a distinct filename and keep its correct extension. Avoid overwriting the source. Large video exports can take time; keep the Mac awake and make sure the destination drive has enough space.
Check the converted file. Open it in the intended app or transfer a copy to the destination device. Confirm that it plays or displays correctly, has the expected dimensions or duration, and retains needed audio, transparency, or subtitles. If it fails, keep the original and try another compatible output setting.

Common Mistakes

Renaming instead of converting: Changing .png to .jpg does not change the image encoding. Export or convert it with an app.
Choosing a format based only on file size: A small file may have lower quality or poor compatibility. Check the receiving device or service first.
Expecting a lossless result from a lossy format: JPEG, MP3, and many video encodings discard information. Repeated conversions can compound quality loss; convert from the original when possible.
Overlooking transparency or metadata: JPEG removes transparency, and some conversion workflows may remove metadata such as location or camera details. Review the output if those details matter.
Assuming every file with the same extension uses the same codec: Containers such as MP4 can hold different video and audio codecs. Check the converter’s supported formats rather than relying on the extension alone.

Tips

Keep an untouched copy of important originals and use descriptive names, such as “poster-web.jpg” or “interview-share.mp4.”
For images, use the original resolution for printing; reduce dimensions only when the intended screen or service does not need them.
For audio, use a lossless format such as WAV or AIFF when preserving editing quality matters. Use a compressed format for convenient sharing when its quality is sufficient.
For video, match the export resolution to the source and playback needs. Upscaling does not restore detail that is absent from the original.
For batches, test one file first. Settings that work for one image or clip may not suit every item in a folder.

Troubleshooting

The format is missing from Preview: Preview does not export every image format. Try opening the file in an app that supports that format or use a trusted converter. Confirm the file opens before attempting a batch.
The file will not open: It may be incomplete, damaged, or encoded with an unsupported codec. Check that the original plays in another compatible app, and obtain a fresh copy if it does not. Do not merely change the extension.
The output is too large: Lower the export quality or resolution, or choose a more efficient format supported by the destination. Make a test export and compare it before converting a whole collection.
The output looks or sounds worse: Return to the original and export again at a higher quality setting. Avoid converting an already compressed copy when the source is available.
The conversion stops or cannot save: Check free disk space, confirm the destination is writable, and try saving locally rather than to a disconnected external or network drive. Close unnecessary apps and retry with one file.
The converted file will not play on another device: Check the device’s supported container and codecs, then export using a compatible preset. Test a short sample before converting a long video.

Frequently Asked Questions

Can I convert images on a Mac without installing an app?
Yes. Preview can export many common image formats. The available choices depend on the image type and macOS version.

Can Finder convert an image?
Some macOS versions offer Quick Actions such as Convert Image in Finder. If you see it in the file’s Quick Actions menu, choose a format and size; otherwise, use Preview.

Can I convert a video using QuickTime Player?
QuickTime Player can export compatible videos using its File > Export As menu. Export choices vary with the source and macOS version; it will not handle every codec.

Will converting a file reduce its quality?
It depends on the formats and settings. Lossy output can reduce quality; a lossless conversion avoids that kind of loss but may create a larger file. Keep the original.

Why does an MP4 file not play on my device?
MP4 is a container, not a guarantee that every device supports the codecs inside it. Check the device’s format requirements and export with a compatible video and audio codec.

Is it safe to use an online converter?
Uploading sends the file to a third party, which may be unsuitable for private or sensitive media. Prefer an offline app for confidential files, and review a service’s privacy and retention information before uploading.

Method: the standard formula for this calculation, rounded as each result states. See how the calculators work or report an error.