Every image format exists for a reason — a specific set of tradeoffs between file size, quality, compatibility, and capability. The reason so many formats coexist is that no single format is optimal for every situation. A format that's ideal for a photograph on a website is wrong for a logo, wrong for professional print work, and wrong for archiving originals. Understanding what each format is designed to do makes the choice straightforward rather than arbitrary.
Here's a practical breakdown of the formats you're most likely to encounter, organised around what they're actually for.
Lossy vs. lossless compression
Lossy compression reduces file size by permanently discarding image data the encoder determines is least perceptible to the human eye. The result is a smaller file, but some detail is irreversibly lost. Re-saving a lossy file compresses it again, degrading quality further. JPG, WebP (lossy mode), HEIC, and AVIF all use lossy compression.
Lossless compression encodes image data more efficiently without discarding any of it. The file can be decompressed back to the exact original pixels. PNG, TIFF, WebP (lossless mode), and GIF use lossless compression. Lossless files are larger than their lossy equivalents, but quality is preserved regardless of how many times the file is saved.
Formats for web photography
WebP is the best current default for photographs on websites. It produces files roughly 25–35% smaller than JPG at equivalent visual quality, supports both lossy and lossless modes, and handles transparency. All major browsers have supported it for several years. For new web projects, WebP should be the default format for any photographic content.
AVIF compresses better than WebP — typically 20–50% smaller than JPG at comparable quality — with support for HDR and wide colour gamuts. Browser support is now broad, though less universal than WebP in non-browser contexts. The tradeoff is slower encoding, which matters for large batch processing. Worth using for image-heavy sites where maximum compression is a priority.
JPG remains the most universally compatible format for photographs. Everything opens it — every browser, every operating system, every email client, every image viewer. For images that need to work reliably outside a web context or with unknown recipient software, JPG is the safest default. For web use specifically, WebP is better in every measurable way; JPG's advantage is legacy compatibility.
Formats for graphics, logos, and transparency
SVG is a vector format that stores images as mathematical descriptions rather than pixels. It scales to any size without quality loss — the same SVG file serves as a 16×16 favicon and a full-page header image equally well. File sizes are tiny for simple graphics. SVG is the right format for any logo, icon, or illustration that appears at multiple sizes. It's not suitable for photographs.
PNG is lossless and supports transparency. It's the right raster format for logos and graphics where you need crisp edges, flat colours, or transparent backgrounds and can't use SVG — for instance, when the image needs to be embedded somewhere that doesn't support SVG. PNG is larger than WebP for photographic content, so for photographs, WebP is the better choice unless transparency is specifically needed.
Formats for print and archival
TIFF is the standard format for professional print work and archiving. It's lossless, supports CMYK colour mode (required for offset printing), and preserves all image data. File sizes are large — a high-resolution TIFF can be 50–100MB — but for print originals that need to survive editing and handoff to a print shop, TIFF is the correct format. Most professional print workflows specify TIFF or PDF at 300 DPI in CMYK.
RAW formats (CR2, NEF, ARW, and others, specific to camera manufacturers) capture unprocessed sensor data — everything the camera recorded before any in-camera processing. They contain more tonal information than any compressed format and give photographers maximum flexibility in post-processing. RAW files are large, proprietary to specific camera models, and require dedicated software to open. They're the working format for professional photography, not a delivery format.
PDF is a document format that can contain images, text, and layout together. It's the standard delivery format for print-ready files — the format you send to a print shop rather than a loose image file. It's also the standard for multi-page documents shared digitally. When the goal is sharing a designed document rather than a standalone image, PDF is the right container.
Formats with specific use cases
GIF supports animation and is limited to 256 colours. It's the format behind animated memes and simple looping graphics on the web. For any animated content more complex than simple illustrations, WebP's animation support is technically superior — smaller files, better quality — but GIF remains the more universally understood format for simple animations and is still widely used.
HEIC/HEIF is Apple's default photo format on iOS and macOS. It achieves better compression than JPG at equivalent quality. The limitation is compatibility outside Apple's ecosystem — many Windows applications, web platforms, and non-Apple services don't handle HEIC reliably. Converting HEIC to JPG or WebP is the standard step before using iPhone photos in contexts outside Apple software.
BMP is an uncompressed Windows format that predates modern compression algorithms. It stores every pixel's colour values without any compression, producing very large files with no quality advantage over lossless alternatives like PNG. BMP has no practical advantage for any current use case — it persists because some older Windows software creates it by default.
Quick reference
For web photographs: WebP, or AVIF if compression is a priority and compatibility is confirmed. For web graphics, icons, and logos: SVG where possible, PNG where SVG isn't suitable. For print originals: TIFF in CMYK at 300 DPI. For professional photography editing: RAW. For sharing designed documents: PDF. For animations: GIF for simple, WebP for anything more complex. For files that need to work with unknown software: JPG.