Your Complete File Format Reference
File formats are the DNA of digital media. Every photo, video, song, document, and webpage you interact with uses a specific format that determines its quality, compatibility, file size, and capabilities. With over a hundred commonly used formats in circulation, it is easy to get lost.
This cheat sheet is your quick-reference guide. It covers every major file format you are likely to encounter in 2026, organized by category, with at-a-glance information about what each format does, when to use it, and when to avoid it. Bookmark this page -- you will come back to it.
For format-specific deep dives, cross-references to detailed guides are included throughout. If you need to convert between any of these formats, ConvertIntoMP4 supports 83 formats and counting.
Video Formats
Video formats are containers that hold video streams, audio streams, subtitles, and metadata. The container determines compatibility, while the codec inside determines quality and compression. For the full breakdown of that relationship, see the container vs codec guide.
| Format | Extension | Best For | Codecs Supported | Compatibility |
|---|---|---|---|---|
| MP4 | .mp4 | Universal use, streaming, sharing | H.264, H.265, AV1, AAC | Universal |
| MOV | .mov | Apple ecosystem, editing | H.264, H.265, ProRes, AAC | Apple + most editors |
| MKV | .mkv | Archiving, multiple tracks | Nearly all codecs | PC players, limited mobile |
| WebM | .webm | Web video, HTML5 | VP8, VP9, AV1, Vorbis, Opus | Chrome, Firefox, Edge |
| AVI | .avi | Legacy use (avoid for new projects) | Most codecs (limited metadata) | Windows, most players |
| WMV | .wmv | Legacy Windows media | WMV7/8/9, WMA | Windows only |
| FLV | .flv | Legacy Flash video (obsolete) | H.264, VP6, MP3 | Requires specific players |
| MPEG / MPG | .mpg, .mpeg | DVD, broadcast | MPEG-1, MPEG-2 | Universal (legacy) |
| TS | .ts | Broadcasting, streaming segments | H.264, H.265, MPEG-2 | Players, streaming systems |
| M4V | .m4v | iTunes / Apple TV content | H.264, AAC | Apple devices, iTunes |
| 3GP | .3gp | Legacy mobile video | H.263, H.264, AMR | Old phones (obsolete) |
| OGV | .ogv | Open-source web video | Theora, Vorbis | Firefox, Chrome (limited) |
Quick recommendation: Use MP4 for everything unless you have a specific reason not to. Convert legacy formats with the MP4 converter. For Apple-specific workflows, see how to convert MOV to MP4.
Pro Tip: When you see a file extension you do not recognize, the first thing to check is whether it is a container or a codec issue. An MP4 file that will not play usually contains a codec your device does not support (like H.265 or AV1), not a problem with the MP4 format itself. The container vs codec guide explains this critical distinction.
Audio Formats
Audio formats fall into three categories: lossless (perfect quality, large files), lossy (reduced quality, small files), and uncompressed (raw data, very large files).
| Format | Extension | Type | Best For | Typical Size (per minute) |
|---|---|---|---|---|
| MP3 | .mp3 | Lossy | Music sharing, podcasts, general use | 1-2 MB (128-256 kbps) |
| AAC | .aac, .m4a | Lossy | Streaming, Apple devices, better than MP3 | 1-2 MB (128-256 kbps) |
| OGG Vorbis | .ogg | Lossy | Open-source projects, gaming | 1-2 MB |
| Opus | .opus | Lossy | VoIP, streaming, low-latency audio | 0.5-1.5 MB |
| FLAC | .flac | Lossless | Music archiving, audiophile playback | 5-10 MB |
| ALAC | .m4a | Lossless | Apple lossless (iTunes, Apple Music) | 5-10 MB |
| WAV | .wav | Uncompressed | Audio editing, production | 10 MB |
| AIFF | .aiff | Uncompressed | Mac audio editing | 10 MB |
| WMA | .wma | Lossy/Lossless | Legacy Windows (avoid) | 1-2 MB |
| MIDI | .mid | Notation | Music composition, instrument control | ~10 KB (instructions only) |
Quick recommendation: MP3 for sharing, FLAC for archiving, WAV for editing. Convert between formats with the WAV to MP3 converter. For a deeper comparison, the lossless vs lossy compression guide covers the tradeoffs.
Pro Tip: MIDI files are not audio recordings -- they are sets of instructions (which note to play, how loud, how long). A MIDI file is like sheet music for computers. The same MIDI file can sound completely different depending on the synthesizer or software instrument that plays it. If you need actual audio, record the MIDI output as WAV or MP3.
Image Formats
Image formats are divided into raster (pixel-based) and vector (math-based) categories. Choosing the right format depends on whether you need photos, graphics, or scalable illustrations.
| Format | Extension | Type | Best For | Transparency | Animation |
|---|---|---|---|---|---|
| JPEG | .jpg, .jpeg | Raster, lossy | Photos, complex images | No | No |
| PNG | .png | Raster, lossless | Screenshots, graphics, logos | Yes | No (APNG yes) |
| WebP | .webp | Raster, lossy/lossless | Web images (best balance) | Yes | Yes |
| AVIF | .avif | Raster, lossy/lossless | Next-gen web images | Yes | Yes |
| GIF | .gif | Raster, lossless (256 colors) | Simple animations, memes | Yes (1-bit) | Yes |
| SVG | .svg | Vector | Logos, icons, illustrations | Yes | Yes (CSS/JS) |
| TIFF | .tif, .tiff | Raster, lossless | Print, archival, scanning | Yes | No |
| BMP | .bmp | Raster, uncompressed | Legacy Windows (avoid) | Limited | No |
| HEIC/HEIF | .heic, .heif | Raster, lossy | iPhone photos | Yes | Yes |
| JPEG XL | .jxl | Raster, lossy/lossless | Future web (limited support in 2026) | Yes | Yes |
| ICO | .ico | Raster | Website favicons | Yes | No |
| RAW | .cr2, .nef, .arw | Raster, uncompressed | Professional photography editing | N/A | No |
| PSD | .psd | Raster (layered) | Photoshop editing | Yes | No |
| EPS | .eps | Vector | Print graphics, illustrations | Limited | No |
Quick recommendation: JPEG for photos, PNG for graphics with transparency, WebP for web delivery, SVG for logos and icons. Convert images with the image compressor or specific converters like PNG to JPG. For web optimization, the optimize images for website guide covers best practices.
Document Formats
| Format | Extension | Best For | Editable | Preserves Layout |
|---|---|---|---|---|
| Sharing, printing, archiving | Limited (with tools) | Yes -- pixel-perfect | ||
| DOCX | .docx | Word processing, editing | Yes | Depends on viewer |
| DOC | .doc | Legacy Word (avoid for new) | Yes | Inconsistent |
| ODT | .odt | LibreOffice, open-source | Yes | Depends on viewer |
| RTF | .rtf | Cross-platform text with basic formatting | Yes | Basic only |
| TXT | .txt | Plain text, code, notes | Yes | No formatting |
| XLSX | .xlsx | Spreadsheets, data | Yes | Depends on viewer |
| CSV | .csv | Data exchange, databases | Yes | No formatting |
| PPTX | .pptx | Presentations | Yes | Depends on viewer |
| LaTeX | .tex | Academic papers, math-heavy docs | Yes (source) | After compilation |
| Markdown | .md | Documentation, README files | Yes | After rendering |
| HTML | .html | Web pages | Yes | Browser-dependent |
Quick recommendation: PDF for sharing (use the Word to PDF converter), DOCX for collaborative editing. For format compatibility across platforms, the file format compatibility guide is essential reading.
Ebook Formats
| Format | Extension | Best For | DRM Support | Reflowable |
|---|---|---|---|---|
| EPUB | .epub | Most e-readers (not Kindle) | Yes | Yes |
| MOBI | .mobi | Legacy Kindle (pre-2022) | Yes | Yes |
| AZW3 / KFX | .azw3, .kfx | Modern Kindle devices | Yes | Yes |
| Fixed-layout books, textbooks | Yes | No | ||
| CBR / CBZ | .cbr, .cbz | Comics, manga | No | No |
| FB2 | .fb2 | Russian/Eastern European e-readers | No | Yes |
Archive and Compression Formats
| Format | Extension | Best For | Compression Ratio | Platform Support |
|---|---|---|---|---|
| ZIP | .zip | Universal file archiving | Good | Universal (built into all OS) |
| 7Z | .7z | Maximum compression | Excellent | Requires 7-Zip (free) |
| RAR | .rar | Legacy archives, split volumes | Very good | Requires WinRAR or compatible |
| TAR.GZ | .tar.gz | Linux/Unix archiving | Good | Linux native, macOS, Windows (7-Zip) |
| TAR.BZ2 | .tar.bz2 | Better compression than gzip | Very good | Linux native, macOS |
| TAR.XZ | .tar.xz | Best compression for tarballs | Excellent | Linux native, macOS |
| GZIP | .gz | Single file compression, web | Good | Universal |
| BROTLI | .br | Web asset compression | Excellent | Web browsers, servers |
| ZSTD | .zst | High-speed compression | Very good | Growing (Facebook-developed) |
Quick recommendation: ZIP for sharing with anyone. 7Z for maximum compression when the recipient has 7-Zip. TAR.GZ for Linux/developer contexts.
Web and Code Formats
| Format | Extension | Purpose | Notes |
|---|---|---|---|
| HTML | .html | Web page structure | The foundation of the web |
| CSS | .css | Web page styling | Controls visual appearance |
| JavaScript | .js | Web interactivity | Runs in browsers and servers |
| JSON | .json | Data interchange | Human-readable, widely used in APIs |
| XML | .xml | Structured data | More verbose than JSON |
| YAML | .yml, .yaml | Configuration files | Human-friendly, used in DevOps |
| TOML | .toml | Configuration files | Simple, used in Rust/Python |
| WASM | .wasm | High-performance web apps | Compiled binary format |
3D and CAD Formats
| Format | Extension | Best For | Notes |
|---|---|---|---|
| STL | .stl | 3D printing | Surface geometry only, no color |
| OBJ | .obj | 3D models, interchange | Wide support, textures via MTL |
| FBX | .fbx | Game development, animation | Autodesk proprietary, widely used |
| glTF / GLB | .gltf, .glb | Web 3D, AR/VR | Modern web standard, compact |
| STEP | .step, .stp | Engineering CAD interchange | ISO standard for CAD |
| DWG | .dwg | AutoCAD drawings | Industry standard for architecture |
Format Selection Decision Guide
Not sure which format to use? Answer these questions:
For Video
- Will it be shared or streamed? Use MP4 (H.264). See the best video formats guide.
- Is it for the web specifically? Consider WebM (VP9/AV1). Check browser format support.
- Is it for archiving with multiple audio tracks? Use MKV.
- Is it for professional editing? Use MOV (ProRes) or MXF.
For Images
- Is it a photo for the web? Use WebP, or JPEG as fallback.
- Does it need transparency? Use PNG or WebP.
- Is it a logo or icon? Use SVG.
- Is it for printing? Use TIFF or high-quality JPEG.
For Documents
- Will the recipient need to edit it? Use DOCX or XLSX.
- Should it look exactly the same everywhere? Use PDF. Convert with the Word to PDF converter.
- Is it just data? Use CSV for tabular data, JSON for structured data.
For Audio
- Is file size a concern? Use MP3 or AAC (lossy).
- Do you need perfect quality? Use FLAC (lossless).
- Is it for editing? Use WAV or AIFF (uncompressed).
Formats to Avoid in 2026
Some formats have been superseded and should be converted to modern alternatives:
- BMP -- Use PNG or JPEG instead
- WMV -- Use MP4 instead
- WMA -- Use MP3 or AAC instead
- FLV -- Use MP4 or WebM instead
- DOC -- Use DOCX instead (convert with the DOC to DOCX converter)
- XLS -- Use XLSX instead
- 3GP -- Use MP4 instead
- RealMedia (.rm) -- Use MP4 instead
- MOBI -- Use EPUB instead (Amazon now supports EPUB on Kindle)
Related Resources
- Video Codecs Explained: H.264, H.265, VP9, AV1 -- Deep dive into video codecs
- Best Video Formats for 2024 -- Detailed video format comparison
- Lossless vs Lossy Compression -- Understanding compression tradeoffs
- File Format Compatibility Guide -- Cross-platform compatibility
- How to Convert Files Between Mac and Windows -- Platform-specific format issues
Summary
With over 100 formats in active use, knowing which one to choose can feel overwhelming. The good news is that for most everyday tasks, you only need a handful: MP4 for video, JPEG and PNG for images, PDF for documents, MP3 for audio, and ZIP for archives. Everything else is a specialty format for specific workflows. When in doubt, convert to the universal option -- it is almost always the right call.
