Always convert from the best source
The golden rule: convert from the highest-quality version you have — the original photo, the master export, the RAW conversion. Conversion to a lossy format discards data; starting from the best source means discarding the least noticeable data.
The worst source is a previously converted or downloaded file: social media recompresses uploads, messaging apps mangle images, and each prior lossy step has already eaten detail. Trace back to the master whenever quality matters.
Set quality deliberately for lossy targets
When converting to JPG or WebP, the quality slider is your fidelity dial. The 75–85 range preserves full visual quality for most images while delivering the size benefits you converted for. Reserve 90+ for detail-critical work like product photography.
Below 70, inspect carefully at 100% zoom — smooth gradients and fine textures degrade first. And match quality to purpose: a thumbnail destined for a 200px slot needs far less fidelity than a hero image.
Understand what each direction costs
Lossless to anything: converting PNG to JPG/WebP is where quality decisions live — the slider governs everything. Lossy to lossless (JPG to PNG): quality is frozen at whatever the JPG had; the PNG just stores those pixels exactly in a bigger file.
Lossy to lossy (JPG to WebP): you are re-compressing compressed pixels, so keep quality high (80+) to avoid compounding artifacts. This direction still usually shrinks files — WebP is simply more efficient — but it cannot improve on the source.
Protect transparency and text
Converting transparent images to JPG destroys the transparency — check the target before converting, not after downloading. For logos and graphics with alpha, PNG or WebP are the only safe targets.
Text-heavy images deserve special care: small text is the first casualty of aggressive lossy settings. Screenshots and infographics convert best to PNG (lossless), or to WebP at 85+ if size matters. When words must stay readable, err toward quality.
Verify, don't assume
After converting, open the result at full size and compare against the original side by side. Look at the usual suspects: edges, gradients, small text, faces. The cards show you sizes; your eyes confirm quality.
For critical work, keep a simple before/after habit: original archived, converted verified, then deployed. Thirty seconds of checking beats discovering a degraded image on the live site — or worse, in print.
Make verification a habit rather than an event: the first conversion of a new batch type gets the full side-by-side treatment, and the rest inherit the approved settings. Light spot-checks thereafter keep quality consistent without slowing you down.
Frequently asked questions
Will converting JPG to WebP improve quality?
No — conversion never adds quality. It can shrink the file at equal quality, but the source's detail is the ceiling. Convert from the best source available.
What quality should I use when converting to JPG?
75–85 for most images; 85+ for detail-critical work. Check smooth gradients and text at 100% zoom before finalizing.
Is converting to PNG always safe?
For quality, yes — PNG is lossless. For file size, no — photos become much larger as PNG. It preserves pixels exactly but rarely the right choice for photographs.
Why does my converted image look worse?
Usually too-low quality on a lossy target, or a lossy-to-lossy chain compounding artifacts. Reconvert from the original at a higher quality setting.