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File format comparisons

28side-by-side answers to "which one should I actually use?"

Most format questions are not "what is this" but "which of these two". Each comparison below gives the verdict in the first paragraph, then a table of the differences that decide it: file size, compatibility, transparency, quality loss and what happens when you convert one into the other.

How to read these comparisons

Three questions settle almost every format choice, in this order. First, where is the file going? A format that only your own machine has to read can be the efficient one; a file going to a stranger, a website or an old system has to be the compatible one. Second, does it need to survive editing? Every save of a lossy format throws away a little more, so a working file and a delivery file should rarely be the same format. Third, is the conversion reversible? Going from a lossless format to a lossy one is a one-way trip, and converting back does not restore what was discarded, it only makes the file bigger.

Where a comparison quotes a size or a compatibility claim, it says which encoder and which platform it applies to. Nothing here is a benchmark of your specific file: your own content, resolution and encoder settings move the numbers, sometimes a lot.

Image

vs.avif vs .jpgUse AVIF for photos on a modern website to cut load times and unlock HDR, with a JPG or WebP fallback for older browsers.vs.avif vs .webpChoose AVIF when squeezing out the smallest possible file matters most and you can accept slower encoding.vs.heic vs .jpgKeep HEIC for storing photos on your iPhone, where the space saving is real and everything reads it.vs.png vs .jpgUse JPG for photographs, where its small files shine and the slight quality loss is invisible.vs.webp vs .gifUse WebP for new animations, it holds far more colours and produces smaller files than GIF at the same length and size.vs.webp vs .jpgChoose WebP for photos on modern websites to save bandwidth without visible quality loss.vs.webp vs .pngUse WebP for images on your own website to cut load times, ideally with a PNG fallback for very old clients.

Video

vs.avi vs .mp4Use MP4 for anything current: it is smaller, plays on every device and browser, and streams properly.vs.mkv vs .mp4Pick MKV when you need multiple subtitle or audio tracks and chapters bundled into one archive-quality file, typically for full movies.vs.mp4 vs .movUse MP4 for sharing, uploading and playback almost anywhere, it is the safer universal default.vs.mp4 vs .webmUse MP4 as the safe default; it plays on every browser and device.

Audio

vs.aac vs .mp3AAC is the better-sounding choice at a given bitrate and is already the default on most streaming platforms.vs.mp3 vs .flacChoose FLAC for archiving music or critical listening, where you want an exact copy at a smaller size than WAV.vs.mp3 vs .wavRecord, edit and mix in WAV for a bit-perfect working file, then export MP3 for sharing, streaming or anywhere device storage and bandwidth matter..

Document

vs.docx vs .odtUse DOCX when the reader uses Microsoft Word, which is most workplaces.vs.pdf vs .docxSend a PDF once the document is finished and needs to look identical everywhere, for contracts, invoices and anything printed.

Archive

vs.zip vs .7zUse ZIP for quick, everyday sharing where the recipient should not need to install anything.vs.zip vs .rarUse ZIP when the recipient needs to open the archive without installing anything.

Code and data

vs.json vs .xmlUse JSON for new APIs, configuration and anything you are designing today, it is smaller and easier to read and write.

Data

vs.avro vs .parquetReach for Avro when you are writing or streaming records, such as messages through Kafka, where row-based storage and schema evolution shine.vs.csv vs .jsonUse CSV for flat, tabular data you plan to open in a spreadsheet or import into a simple table.vs.csv vs .xlsxUse CSV when you are exporting or importing plain data between different programs or databases and want the widest compatibility.vs.geojson vs .kmlChoose GeoJSON for web maps, APIs and modern GIS tooling, where its JSON structure is a natural fit.vs.parquet vs .csvUse CSV for small, human-readable exchanges and anything that must open in a spreadsheet.vs.tsv vs .csvUse CSV as the universal default, since every tool expects it.

Font

vs.ttf vs .woff2Install TTF on a desktop, that is exactly what it is built for.

eBook

vs.epub vs .mobiUse EPUB for any eBook today, it is the open standard and modern Kindles accept it directly through Send to Kindle.

Disk image

vs.vhd vs .vmdkUse VHD or VHDX for Hyper-V and Windows-centric setups; use VMDK for VMware.

Frequently asked questions

Does converting between formats always lose quality?

Only when the target is lossy. Going from PNG to WebP-lossless or from WAV to FLAC keeps every bit. Going to JPG, MP3 or lossy WebP discards data permanently, and converting back afterwards does not restore it, it only makes the file bigger.

Is the newer format always the better choice?

No. Newer formats such as HEIC, AVIF and WebP are more efficient, but efficiency only matters if the thing that opens the file supports it. For anything leaving your own machine, compatibility usually beats file size.

Can I just rename a file to change its format?

No. The extension is a label, not the contents. Renaming photo.heic to photo.jpg leaves HEIC bytes inside a file that claims to be a JPG, and most software will refuse it. The in-browser identifier on this site spots exactly that mismatch.

Which format should I keep as the master copy?

The least compressed one you have. Keep the raw, the PSD, the WAV or the lossless export as the working file, and generate the shareable JPG, MP3 or MP4 from it each time. Editing and re-saving a lossy file compounds the damage on every pass.

Not the pair you were after?

Every format page carries its own comparison links plus the alternatives worth considering. Start from the format you have.

Browse the full A-Z format indexImage formatsMagic-numbers reference