Three formats, three very different jobs. Picking correctly is usually the difference between a sharp 80 KB image and a blurry 2 MB one.
Most image format advice is either too vague to act on or too technical to care about. The useful version fits in a sentence: JPG for photographs, PNG for graphics with sharp edges, WEBP when you control the audience. Everything below is why.
JPG: built for photographs
JPG uses lossy compression tuned specifically for the way photographs look — smooth gradients, gradual tonal variation, no hard edges. It discards detail your eye is poor at noticing and achieves remarkable file sizes as a result.
Use it for: photographs, anything with continuous tone, images where file size matters more than perfect fidelity.
Avoid it for: screenshots, logos, line art, charts, or anything containing text. JPG compression produces visible fringing around sharp black-on-white edges — those faint halos around letters in a compressed screenshot.
Watch out for: generation loss. Every save re-compresses, so repeatedly editing and saving a JPG degrades it cumulatively. Edit from an original, export to JPG once.
PNG: built for graphics
PNG is lossless. Every pixel comes back exactly as it went in, no matter how many times you save. It also supports an alpha channel for genuine transparency.
Use it for: screenshots, logos, icons, charts and diagrams, images with text, anything needing transparency, and any file you will edit repeatedly.
Avoid it for: photographs. A PNG photograph is often five to ten times the size of an equivalent JPG with no visible benefit.
Worth knowing: PNG compresses flat areas of uniform colour extremely well, which is why screenshots of documents are often surprisingly small, while a PNG of a sunset is enormous.
WEBP: the modern compromise
WEBP offers both lossy and lossless modes, supports transparency, and typically produces files 25–35% smaller than equivalent JPG or PNG. On paper it replaces both.
Use it for: websites, where every kilobyte affects load time and the audience is browsers. Support is now effectively universal in current browsers.
Be careful with: files people will download and open in other software. Older image viewers, some email clients and various desktop applications still handle WEBP poorly. It is an excellent delivery format and a risky interchange format.
A decision table
- Photo for email or printing → JPG
- Photo for a website → WEBP, with JPG as fallback
- Screenshot → PNG
- Logo or icon → PNG (or SVG, if you have the vector)
- Chart or diagram → PNG
- Anything needing transparency → PNG or WEBP
- Master copy you will keep editing → PNG, or the editor's native format
Converting between them
Two asymmetries are worth remembering.
Converting JPG to PNG does not restore quality. Compression artefacts already in the JPG are preserved exactly. The conversion prevents future loss; it cannot undo past loss. The file will usually get considerably bigger.
Converting PNG to JPG discards transparency. Transparent areas are filled, normally with white. If the image was a logo intended to sit on a coloured background, this will be obvious and unwelcome.
Tools for both: PNG to JPG and JPG to PNG, both running in your browser. For iPhone photos, start with HEIC to JPG, which also outputs PNG and WEBP directly.
Pixellwork Editorial
Documents & Privacy
Published September 28, 2026