WebP vs AVIF vs PNG vs JPEG Choosing Image Formats for the Web

Picking the wrong image format is one of those low-key performance killers. A PNG where a JPEG belonged inflates your page weight by 3–5×. Serving JPEG in 2025 when WebP would do the same job at 30% less size is wasted bandwidth. The decisions aren’t complicated — you just need a clear map.

Here’s how each format works, when to use it, and how to convert between them using an image format converter or command-line tools.

JPEG

JPEG has been the default format for photographs since the 1990s, and it still earns that position. It uses lossy compression: some image data is discarded during encoding, but at quality settings of 75–85, the difference is invisible to the human eye. JPEG does not support transparency.

Best for: Photos, product images, illustrations with complex gradients, any photographic content without transparency needs.

Avoid when: You need a transparent background, or the image contains text and sharp edges where compression artifacts become visible.

PNG

PNG uses lossless compression — every pixel is preserved exactly as encoded. It supports a full alpha channel, which makes it the right choice for anything requiring transparency: logos, UI screenshots, icons, overlays, and images with text.

The tradeoff is file size. PNG is routinely 2–5× larger than an equivalent JPEG for photographic content. The most common mistake: saving a photograph as PNG because it “looks better.” It doesn’t look better — it just hasn’t been compressed yet. If your photo doesn’t need transparency, PNG is the wrong format.

Best for: Screenshots, UI assets, logos, icons, images with text, anything requiring transparency.

Avoid when: Serving a photograph that doesn’t require transparency.

WebP

WebP was released by Google in 2010 and has now reached near-universal browser support (97%+ as of 2025). It supports both lossy and lossless compression, full transparency, and animation — essentially a superset of JPEG and PNG capabilities in a single format.

Compression is roughly 25–35% better than JPEG at equivalent visual quality. For lossless use cases, WebP files are consistently smaller than PNG. There’s no longer a meaningful compatibility reason to avoid WebP on modern websites.

Best for: All-purpose replacement for JPEG and PNG. Photos, UI assets, anywhere you’d previously have defaulted to the older formats.

AVIF

AVIF is derived from the AV1 video codec and offers the best compression of any mainstream web image format — typically 20–50% smaller than WebP at comparable visual quality. It supports HDR color, wide color gamut, and alpha channel transparency.

Browser support sits around 93% globally. The main friction is encoding speed: AVIF encoding is significantly slower than WebP, though the tooling is improving rapidly. For most production workflows, you generate AVIF offline and serve it statically — encoding time doesn’t affect page load time.

Best for: High-quality photos, hero images, anywhere compression gains outweigh offline encoding time.

GIF, SVG, and the Others

GIF is functionally obsolete. Its 256-color limit and poor compression made it mediocre for animation and useless for photographs. WebP animated, CSS animation, and <video> all produce better results at smaller sizes. Don’t use GIF in new work.

SVG isn’t a raster format — it’s XML markup describing vector shapes. Use it for icons, logos, and line-based illustrations that need to scale cleanly at any size without blurring. It’s not appropriate for photographs or photorealistic images.

Format Comparison at a Glance

Format	Lossy	Transparency	Browser Support	Best For	File Size vs JPEG
JPEG	Yes	No	100%	Photos, gradients	Baseline
PNG	No	Yes	100%	Screenshots, UI, icons	2–5× larger
WebP	Both	Yes	97%+	All-purpose modern replacement	~30% smaller
AVIF	Both	Yes	93%+	High-quality photos	~45% smaller
GIF	No	Yes (1-bit)	100%	Legacy animation only	Avoid
SVG	N/A	Yes	100%	Icons, logos, illustrations	N/A

How to Convert Between Formats

The fastest way to convert images without installing anything: the IO Tools Image Converter handles JPEG, PNG, WebP, AVIF, GIF, and more — upload your file, choose the output format, download. It works entirely in the browser for formats supported client-side, and uses server-side processing for AVIF.

For batch processing or build pipelines, ffmpeg and ImageMagick are the standard tools:

# Convert to WebP (ffmpeg)
ffmpeg -i input.jpg -quality 85 output.webp

# Convert to AVIF (ffmpeg)
ffmpeg -i input.jpg -c:v libaom-av1 -crf 30 output.avif

# Convert to WebP (ImageMagick)
convert input.png -quality 85 output.webp

# Batch convert all JPEGs to WebP
for f in *.jpg; do convert "$f" -quality 85 "${f%.jpg}.webp"; done

After converting, you can reduce file size further with the IO Tools Image Compressor — useful for squeezing out additional bytes before deployment without another round-trip conversion.

Serving Modern Formats with a Fallback

The <picture> element lets you serve AVIF and WebP to capable browsers while falling back to JPEG for older ones. The browser picks the first <source> format it supports:

<picture>
  <source srcset="hero.avif" type="image/avif">
  <source srcset="hero.webp" type="image/webp">
  <img src="hero.jpg" alt="Hero image" width="1200" height="600">
</picture>

This gives you maximum compression where it’s supported without breaking compatibility. AVIF for browsers that support it, WebP as the second choice, JPEG as the guaranteed fallback. The <img> tag is what gets indexed by search engines and read by screen readers — fill in alt text accordingly.

The Decision at a Glance

• Photo without transparency → WebP (or AVIF + WebP fallback if you’re optimizing hard)
• Transparent background → WebP (PNG if maximum compatibility is required)
• Logo, icon, illustration → SVG
• UI screenshot or diagram → PNG
• Maximum browser compatibility → JPEG + PNG
• Maximum performance → AVIF + WebP fallback via <picture>

The short answer: default to WebP for photos and UI assets, SVG for anything vector. Add an AVIF <source> when performance is critical. Reach for JPEG and PNG when you have a specific reason — not as default choices.

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