With dozens of video and audio formats in circulation, choosing the right one can be confusing. This guide breaks down the most common formats, explains when to use each, and shows you how to convert between them.
Video Formats
MP4 (MPEG-4 Part 14)
MP4 is the universal standard for video. It offers excellent compression with the H.264 or H.265 codec, plays on virtually every device and platform, and supports embedded subtitles and multiple audio tracks. If you are unsure which format to use, MP4 is almost always the right answer.
WebM
WebM is an open format developed by Google, optimized for web playback. It uses the VP9 (or AV1) video codec and Opus audio codec, delivering excellent quality at smaller file sizes than MP4 in many cases. WebM is natively supported in Chrome, Firefox, and Edge, making it ideal for web-embedded video.
AVI (Audio Video Interleave)
AVI is a legacy format from Microsoft. While it supports high quality, files tend to be very large because older AVI files often use minimal compression. It is still encountered in older footage and some professional workflows, but MP4 is a better choice for most modern use cases.
MOV
MOV is Apple's QuickTime format. It supports high-quality video and is commonly used in Apple ecosystems — iPhones, Final Cut Pro, and macOS. If you need cross-platform compatibility, converting MOV to MP4 is usually the best path.
Audio Formats
MP3
MP3 remains the most widely supported audio format. At 128-320 kbps, it offers a good balance between quality and file size. It is the go-to format for music, podcasts, and any audio that needs maximum compatibility. Converting WAV to MP3 can reduce file size by 80-90% with minimal perceptible quality loss.
WAV (Waveform Audio)
WAV is an uncompressed audio format that preserves full audio fidelity. It is the standard for professional audio editing, music production, and archiving. The trade-off is file size — a 3-minute WAV file can be 30 MB or more, compared to 3-5 MB for MP3.
OGG (Ogg Vorbis)
OGG is an open-source compressed audio format that generally offers better quality than MP3 at the same bitrate. It is popular in gaming, open-source software, and web applications. Browser support is strong across Chrome, Firefox, and Edge.
FLAC (Free Lossless Audio Codec)
FLAC compresses audio without any quality loss — like ZIP for audio files. It reduces file size by about 50-60% compared to WAV while preserving every bit of the original recording. Audiophiles and archivists prefer FLAC for its perfect fidelity.
When to Convert
- Sharing video online: Convert to MP4 (H.264) for maximum compatibility
- Extracting audio from video: Use MP4 to MP3 to pull the audio track
- Reducing audio file size: Convert WAV to MP3 for 80-90% smaller files
- Web-optimized video: Consider WebM for smaller file sizes in browsers
- Creating GIFs: Convert video to GIF for short, looping animations
- Archiving audio: Keep originals in WAV or FLAC; create MP3 copies for sharing
All of these conversions can be done instantly in your browser with Convert-a-Lot — no sign-up, no upload, completely free and private.