A practical guide to file formats: when to use MP4, MP3, JPG and PNG

File formats look interchangeable until the wrong one costs you quality, space, or compatibility. Here's a practical reference for the formats people deal with daily.

JPG: photos and anything with gradients

JPG compresses well for photographs and complex images with lots of color variation, at the cost of some quality loss. It's the right default for photos, but a poor choice for screenshots with text or logos — compression artifacts make sharp edges look fuzzy.

PNG: screenshots, logos, and anything needing transparency

PNG is lossless, which means screenshots and text stay perfectly crisp, and it supports transparent backgrounds, which JPG cannot do at all. The tradeoff is larger file sizes for photographic content — use PNG for graphics and UI, JPG for photos.

MP4: video, almost always

MP4 (H.264/H.265) is the format with the widest device and platform support for video. Unless you have a specific reason to use something else, MP4 is the safe default for saving, sharing or downloading video content.

MP3: audio when compatibility matters most

MP3 plays on essentially everything, which makes it the safest choice when you don't control the playback device. For higher quality at a similar file size, formats like AAC or Opus are technically better, but MP3's universal support is hard to beat for general use.

WebP: the modern web default

WebP gives JPG-like compression with PNG-like transparency support and noticeably smaller file sizes than either. Most modern browsers and apps support it now — it's increasingly the better default for web images specifically.

A simple rule of thumb

If it has text or sharp edges → PNG. If it's a photo → JPG (or WebP on the web). If it's video → MP4. If it's audio and you don't know what will play it → MP3. Past that, the differences mostly matter for storage efficiency, not compatibility.

Getting the format right the first time saves you from a re-save (and a quality loss) later.