Does converting JPG to PNG improve quality?

No. The JPG's lossy artefacts are already baked into the pixel values. PNG losslessly preserves them while making the file 5–10× larger.

Why are screenshots so big as JPG?

Screenshots are full of hard edges (text, UI lines) which JPG's DCT compresses badly — at quality 90 the file is roughly 80% of a PNG. Use PNG for text screenshots, JPG only if a photo dominates the screen.

Can I save a PNG with transparency as JPG?

You can, but JPG has no alpha channel. The encoder fills the transparent regions with a flat color (white or black). The transparency is gone permanently.

Is PNG-8 worth it for icons?

Yes — for any icon with ≤256 distinct colors, PNG-8 produces a 50–70% smaller file than PNG-24 with no visible difference.

Why does Photoshop default to JPG quality 12?

Adobe's quality 12 maps to about JPG quality 100 — which adds 30–60% file size with zero visible improvement vs quality 90. Drop to quality 8 (≈ JPG 85) for routine sharing.

Are JPG and PNG patent-free?

Yes, both are patent-unencumbered. Original JPG patents expired in the 2000s; PNG was specifically designed to avoid the GIF/LZW patent era and remains free.

PNG or JPG — the decision tree, in 60 seconds

Tomoda HinataTool author & maintainerPublished Apr 26, 202611 min read

PNG and JPG were designed for different jobs. JPG is a lossy DCT codec optimised for photographs and continuous-tone images; PNG is a lossless predictor codec with full alpha channel optimised for graphics and screenshots. Almost every ‘which should I use?’ question collapses to: photo → JPG, graphic with transparency or hard edges → PNG, photo with transparency → switch to WebP.

What each format is actually optimised for

JPG (1992) uses 8×8 block DCT compression — it sacrifices high-frequency detail in a way that's invisible on photos but disastrous on hard edges (text, line drawings, screenshots). PNG (1996) uses a lossless predictor + DEFLATE — every pixel is reconstructed exactly, but continuous-tone photos compress poorly because the predictors can't model gradients efficiently. JPG handles photos at 5–10% of the size PNG would need for the same image; PNG handles graphics at 25–50% of the size JPG would need at quality 95+.

When to pick JPG

Photographs (camera shots, screenshots of photos, illustrations with smooth gradients), email attachments where universal compatibility matters, anything destined for print where the printer driver speaks JPG natively. Quality 78 for routine sharing, quality 90 for archival, quality 95+ if you're going to edit again later. JPG does not have alpha — drop transparency before saving.

When to pick PNG

Logos with transparent backgrounds, screenshots with text, line drawings, comics with flat colors, UI mockups, anything that will be edited again later (PNG is lossless, JPG accumulates errors with each edit). PNG-8 (256-color palette) is excellent for icons and simple graphics; PNG-24 + alpha for logos and complex transparency. The penalty for picking PNG when JPG would work is just file size — you pay 5–10× for nothing visible.

When to pick neither (WebP)

Photo with transparency (e.g., a person's headshot with the background removed) is the gap PNG and JPG both miss. PNG handles the transparency but is 5× too large; JPG halves the size but throws away the alpha. WebP solves both — lossy compression with full alpha — and is supported by every modern browser. For email, fall back to PNG; for everything else, WebP wins.

Conversion pitfalls

JPG → PNG never improves quality — the JPG's compression artefacts are baked into the pixels, and PNG just preserves them losslessly while inflating the file 5–10×. PNG → JPG of a transparent image silently fills the alpha with white (or black, depending on the encoder) — once saved, the transparency is gone forever. For round-trip editing, keep a PNG master and only export JPG as the final deliverable.

Same source rendered as JPG quality 90 vs PNG-24 vs WebP quality 82
Source type	JPG Q90	PNG-24	WebP Q82
1080p photo	245 KB	1.65 MB	165 KB
Logo with transparency (800×800)	(no alpha)	11 KB	8 KB
UI screenshot 1920×1080	(soft edges)	92 KB	55 KB (lossless)
Comic panel (flat colors)	(blocking on edges)	60 KB	45 KB (lossless)

Measured on 14" MacBook Pro M2, Chrome 139, sample assets via the in-browser converter (2026-04-26).

Frequently asked questions

Does converting JPG to PNG improve quality?
No. The JPG's lossy artefacts are already baked into the pixel values. PNG losslessly preserves them while making the file 5–10× larger.
Why are screenshots so big as JPG?
Screenshots are full of hard edges (text, UI lines) which JPG's DCT compresses badly — at quality 90 the file is roughly 80% of a PNG. Use PNG for text screenshots, JPG only if a photo dominates the screen.
Can I save a PNG with transparency as JPG?
You can, but JPG has no alpha channel. The encoder fills the transparent regions with a flat color (white or black). The transparency is gone permanently.
Is PNG-8 worth it for icons?
Yes — for any icon with ≤256 distinct colors, PNG-8 produces a 50–70% smaller file than PNG-24 with no visible difference.
Why does Photoshop default to JPG quality 12?
Adobe's quality 12 maps to about JPG quality 100 — which adds 30–60% file size with zero visible improvement vs quality 90. Drop to quality 8 (≈ JPG 85) for routine sharing.
Are JPG and PNG patent-free?
Yes, both are patent-unencumbered. Original JPG patents expired in the 2000s; PNG was specifically designed to avoid the GIF/LZW patent era and remains free.

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