Running a free image converter teaches you a lot about how people actually use image formats — and the most common pattern we see is people converting images for the wrong reasons. PNG screenshots that should be WebP. Photos exported as PNG "because it's lossless." Logos saved as JPEG with compression halos around every edge.
This guide explains what each format is actually good at, so you can stop guessing.
The one-paragraph version
Photos on the web → WebP (or AVIF if you can serve fallbacks). Screenshots, logos, and anything with sharp edges or text → PNG, converted to lossless WebP for production. Photos for print or maximum compatibility → JPEG. Anything needing transparency → PNG or WebP, never JPEG. That covers 95% of cases; the rest of this article is the reasoning.
JPEG: the 30-year-old default that refuses to die
JPEG compresses by dividing the image into 8×8 pixel blocks and discarding high-frequency detail your eye barely notices. This works brilliantly for photographs — smooth gradients, organic textures — and terribly for sharp edges, which is why text on a JPEG grows fuzzy "mosquito noise" artifacts.
- Use it when: you need universal compatibility (email clients, old devices, government portals that reject anything else) or you're printing photos.
- Avoid it for: screenshots, diagrams, logos, and anything with transparency — JPEG simply has no alpha channel, so transparent areas become solid white or black.
- Quality setting: 80–85 is the sweet spot for photos. Above 90 the file size climbs steeply for differences you cannot see; below 70 the artifacts become visible.
PNG: lossless, transparent, and frequently misused
PNG is lossless — every pixel is preserved exactly — and supports full alpha transparency. That makes it the correct choice for UI screenshots, logos, icons, and charts. It also makes it the wrong choice for photographs: a photo saved as PNG is routinely 5–10× larger than a visually identical JPEG or WebP, because lossless compression can't exploit the "your eye won't notice" shortcut.
The rule of thumb: if a human drew it, PNG; if a camera captured it, not PNG.
WebP: the current best all-rounder
WebP, developed by Google, does both lossy and lossless compression, supports transparency and animation, and is now supported by every current browser — the old "but Safari…" objection died years ago. In our own testing while building the converter:
- Lossy WebP at quality 80 is typically 25–35% smaller than an equivalent-quality JPEG.
- Lossless WebP is typically 20–45% smaller than the same image as PNG — same pixels, smaller file.
For a website in 2026, WebP is the safe default for everything. The only remaining reasons to avoid it are non-browser destinations: some desktop software, printing services, and older CMS uploaders still reject it.
AVIF: better compression, more caveats
AVIF (based on the AV1 video codec) compresses photos another 20–30% beyond WebP at comparable quality, and it particularly shines at low bitrates — an aggressively compressed AVIF degrades gracefully into smoothness, where JPEG degrades into blocky artifacts. Browser support is now solid across Chrome, Firefox, Safari, and Edge.
The caveats: encoding is much slower (noticeable when converting large batches), very old devices and much non-browser software still can't open it, and progressive rendering support is weaker than JPEG's. Use AVIF when bandwidth matters most — hero images, image-heavy galleries — ideally via the <picture> element with a WebP or JPEG fallback:
<picture>
<source srcset="hero.avif" type="image/avif">
<source srcset="hero.webp" type="image/webp">
<img src="hero.jpg" alt="Product hero shot" width="1200" height="630">
</picture>Quick decision table
| Your image is… | Best format | Why |
|---|---|---|
| A photo for a website | WebP (AVIF with fallback) | Smallest file at equal visual quality |
| A screenshot or diagram | PNG → lossless WebP | Sharp edges stay sharp; no artifacts on text |
| A logo or icon needing transparency | PNG or lossless WebP (or SVG if vector) | Alpha channel; exact colors |
| A photo to email or print | JPEG (quality 85+) | Opens everywhere, print pipelines expect it |
| An animated meme | WebP or MP4 | GIF files are enormous; both alternatives are ~10× smaller |
Two mistakes we see constantly
1. Converting a JPEG to PNG "to improve quality." Compression loss is permanent. Converting a compressed JPEG into PNG produces a file that is 8× larger with exactly the same artifacts, faithfully preserved. Always keep your original exports; convert from the source, not from a previous conversion.
2. Serving 4000-pixel images scaled down by CSS. Format choice saves you 30%; resizing the image to the size it's actually displayed at often saves 90%. Resize first, then choose the format — our image compressor does both in one step, entirely in your browser.
Format churn on the web is slow — JPEG has outlived a dozen "JPEG killers." But the practical answer today is simple: WebP by default, PNG for graphics you'll edit again, JPEG for compatibility, AVIF when every kilobyte counts.
