PNG vs JPG: Which Image Format Should You Use?
PNG and JPG are the two formats everyone has, and people pick between them wrong every day — exporting screenshots as JPG into mush, or shipping photographs as 8 MB PNGs. The right choice isn't preference; it's determined by what's inside the image. This guide gives you the decision rule, the reasons behind it, and the clean way to convert between the two when you pick wrong.
The one-sentence decision rule
Photographs → JPG. Everything sharp, flat or transparent → PNG. That's 90% of decisions. The reason lives in how the formats compress: JPEG was designed for continuous-tone images (photos) where small imperfections are invisible, while PNG stores pixels losslessly, excelling at flat colours and hard edges — and staying enormous on photos.
We put numbers on this in our compression benchmarks: a UI frame stored as a plain PNG weighed about 10× more than a matched-quality JPEG encoding of the same frame, while a photograph at JPEG q80 hit a sweet spot PNG couldn't approach without absurd file sizes. The formats are specialised; neither is “better”.
Why photos belong to JPG
A photo contains millions of subtly varying colours — exactly the kind of data JPEG's mathematics (discrete cosine transform) compresses ruthlessly well. It discards detail your eyes don't prioritise, at quality levels you control. The cost: JPEG is lossy (every save degrades slightly) and has no transparency. But for a photograph viewed on a screen, at quality 75–85, JPEG is nearly free visually and dramatically lighter than the alternatives.
Why screenshots, logos and text belong to PNG
Screenshots, diagrams, logos and anything with text have flat colour areas and razor-sharp edges. JPEG's method blurs exactly those edges — the classic “fuzzy text” artefact — and invents ringing patterns around high-contrast borders. PNG's lossless compression records every pixel exactly: text stays crisp, colours stay exact, and transparency (the alpha channel) is preserved. On flat graphics, PNG is often also smaller than a high-quality JPEG, because JPEG wastes bits trying to reproduce edges it keeps getting wrong.
Converting PNG → JPG (and back)
- Open PNG to JPG when you want the smaller, compatibility-first format for a photo or a flat image you don't need transparency in.
- Transparency must go somewhere: the tool fills it with white (or a colour you choose) — that's a fact of the format, not a bug.
- Pick quality 80–90 for the conversion; screenshots with text deserve the higher end.
- The reverse direction — JPG to PNG — makes sense when you're about to start editing (lossless headroom) or need transparency, but it will not restore quality JPEG already lost.
One warning worth framing: JPG → PNG cannot un-lossy an image. Converting gives you a lossless container holding lossy data. It solves compatibility and editing-chain problems, not quality ones.
A field guide to the artefacts you'll meet
Each format fails in its own characteristic way, and recognising the failure tells you which lever to pull:
- Mosquito noise / ringing (fine jagged speckle along sharp edges, like text or a fence against the sky) — JPEG's signature at lower qualities. Fix: keep JPEG for photos, move edge-heavy content to PNG/WebP; or raise JPEG quality above ~80 for that image.
- Blocking (visible square tiles in flat gradients, e.g. sky) — JPEG pushed too far. The image was compressed well past its quality budget; re-compress from the original at a saner level.
- Blurry text after converting a screenshot to JPG — the artefact everyone notices first. Re-convert to PNG; screenshots should never pass through lossy JPG.
- Banding (smooth gradients stepping into visible rings) — happens in both families at low bit depth or low quality; PNG 8-bit palettes cause it on gradients too. Fix: higher-quality export or full-colour PNG/WebP.
- Halos around dark text on light backgrounds — aggressive sharpening plus JPEG. Usually baked in at export; source from the original.
The meta-rule behind all five: artefacts are edit history. The fix is almost never "compress this file better" — it's "go back one step and export differently", which is why keeping originals is the cheapest quality insurance there is.
The modern third option: WebP
Where does WebP fit? Everywhere between: lossless mode beats PNG by 50–70% on graphics (measured in our benchmarks), lossy mode beats JPEG by ~7.5% at matched quality on photos, and it supports transparency in both modes. For websites, it's the pragmatic default today. The reason PNG and JPG still matter: universal compatibility outside browsers and in older software. The professional pattern — publish WebP, archive PNG, share JPG — uses each format where it's strongest. The WebP Converter and PNG to WebP tools cover the moves.
Ready to try it? Free, private, no signup.
Open PNG to JPGFrequently Asked Questions
Should a screenshot be PNG or JPG?
PNG, almost always. Screenshots contain text, flat colour areas and sharp edges — exactly what JPEG's lossy compression blurs and rings around. PNG keeps text crisp and often compresses screenshots to a comparable or smaller size than high-quality JPEG anyway.
Why did my PNG get a white background after converting to JPG?
JPEG has no transparency channel, so the converter must flatten the alpha layer onto a colour — white by convention. If you need transparency, stay with PNG (or WebP); if the destination is a photo print or a form that only takes JPG, choose the fill colour thoughtfully before converting.
Is PNG higher quality than JPG?
PNG is lossless — it stores every pixel exactly — so it never adds artefacts, while JPG does at any quality below 100. But 'higher quality' only matters for the right content: on photographs, a good JPG looks identical to a PNG at a fraction of the size, and on flat graphics PNG is both sharper and smaller. Pick by content, not by prestige.
When should I convert JPG to PNG?
When the file is about to enter an editing chain (every PNG re-save is lossless; every JPG re-save compounds loss) or when you need transparency. Don't convert for quality's sake — pixels JPEG already lost stay lost; a converted file is a lossless wrapper around lossy data.
What about WebP — does it replace both?
For websites, largely yes: WebP lossless beats PNG by 50–70% on graphics and WebP lossy beats JPEG by ~7.5% at matched quality in our measurements, with transparency in both modes. PNG and JPG remain the compatibility formats for software, printing and sharing to unknown devices.