JPG vs PNG: Which Image Format Should You Use?
Short answer
Use JPG for photographs and PNG for anything with transparency, text or sharp edges. The distinction is not quality but content type: JPG's compression is designed for smooth photographic gradients and produces visible artefacts around hard edges.
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The one rule that decides it
JPEG compression works by discarding detail the eye is least likely to notice, and it assumes the image is photographic — smooth gradients, gradual transitions, no hard boundaries.
Give it a screenshot with text, and those assumptions break. The compression produces visible smudging around every letter, an artefact called ringing. PNG has no such problem because it stores every pixel exactly.
So the rule is about content, not quality: photograph → JPG, anything designed → PNG.
| JPG | PNG | |
|---|---|---|
| Compression | Lossy | Lossless |
| Transparency | No | Yes, full alpha |
| Best for | Photographs | Graphics, text, screenshots |
| File size (photo) | Small | Several times larger |
| File size (flat graphic) | Larger, with artefacts | Small |
| Re-saving | Degrades each time | No degradation |
Why converting JPG to PNG does not improve quality
This is the single most common misunderstanding about image formats. PNG is lossless, so people reasonably assume converting to it recovers quality.
It does not. Lossless means PNG stores exactly what it is given — and what it is given is a JPEG that already had detail discarded when it was first saved. The compression artefacts are now part of the image data. PNG preserves them faithfully, in a much larger file.
How much larger depends entirely on the content, and 'three to five times' — the figure this page used to give — turns out to be far too tidy. In our own measurements the multiplier ranged from 1.1× on flat colour to 35× on a smooth gradient, with noisy, photograph-like content at 6.6×. The direction is reliable; the number is not.
The conversion is still useful for one thing: it stops further degradation. If you are about to edit and re-save an image repeatedly, converting to PNG first prevents each save from compounding the loss.
What about WebP?
For anything on the web, WebP is usually the better answer than either. It does both jobs — lossy compression for photos and lossless with transparency for graphics — and produces smaller files than both in their respective roles.
The catch is outside the browser: desktop applications, print services and older software often cannot open WebP. If the file needs to leave the web, JPG and PNG remain the safe choices.
- Photograph for the web → WebP, or JPG if compatibility matters
- Screenshot, logo, or anything with text → PNG
- Anything needing transparency → PNG or WebP, never JPG
- About to edit repeatedly → work in PNG, export to JPG at the end