What Is the Best Image Format for Websites in 2026?

Your images are probably too big. The average web page is over 2 MB, and images account for nearly half of that weight. Picking the right format for each image is the single easiest way to speed up your site.

But with JPG, PNG, WebP, AVIF, and SVG all available, how do you choose? Each format exists for a reason. Using the wrong one wastes bandwidth. Using the right one makes your pages fast without sacrificing quality.

Here's exactly which format to use and when.

Which Format Should You Use for Photos?

Photos are the heaviest images on most websites. Landscapes, portraits, product shots, food photos, travel images. Getting the format right here has the biggest impact.

Best choice: AVIF. It produces the smallest files. A photo that's 1 MB as JPG becomes 500-600 KB as AVIF at the same visual quality. That's a 40-50% reduction. Browser support is at 93% and growing.

Second choice: WebP. Files are 25-35% smaller than JPG. Browser support is over 97%. If you want the safest modern option, WebP is it.

Fallback: JPG. Still works everywhere. Use it as a last-resort fallback for the small percentage of users on very old browsers.

Never: PNG for photos. A photo saved as PNG is 5-10 times larger than it needs to be. PNG was not designed for photographic content. If you see PNG photos on your site, convert them immediately.

The ideal setup uses the HTML <picture> element:

<picture>
  <source srcset="photo.avif" type="image/avif">
  <source srcset="photo.webp" type="image/webp">
  <img src="photo.jpg" alt="Description">
</picture>

The browser picks the best format it supports. Modern browsers get AVIF. Older ones get WebP. Very old ones get JPG.

What About Images That Need Transparency?

Transparent images (logos on colored backgrounds, product cutouts, icons that float on any surface) need a format that supports alpha channels.

Best choice: WebP. Full transparency support. Files are 30-70% smaller than PNG with transparency. Supported by 97%+ of browsers.

Alternative: AVIF. Even smaller than WebP with transparency. But 93% browser support means you need a fallback.

Fallback: PNG. Perfect transparency support. Larger files. Use it as the fallback in a <picture> element.

Never: JPG for transparent images. JPG doesn't support transparency at all. Transparent areas become white (or black). There's no workaround.

A common mistake: saving product photos with transparent backgrounds as PNG. A single product cutout in PNG can be 2-3 MB. The same image in WebP is 200-400 KB. Multiply by 50 products on a category page and you've saved 100 MB of data.

Should You Use SVG for Logos and Icons?

Yes. SVG is the best format for vector graphics on the web. Logos, icons, simple illustrations, and diagrams should almost always be SVG.

Why SVG wins for vectors:

• Scales to any size without losing quality
• File sizes are tiny (often 2-10 KB)
• Can be styled with CSS
• Can be animated
• Accessible (screen readers can read SVG text)

When not to use SVG:

• Photos (SVG can't represent photos efficiently)
• Complex illustrations with many colors and gradients (file size gets huge)
• When the platform doesn't accept SVG (some social media, email clients)

If you have a logo as PNG at 80 KB, replacing it with an SVG version at 5 KB saves 94% and the SVG version looks sharper on every screen size.

For situations where you can't use SVG (email, social media), convert it to WebP or PNG at the specific dimensions you need. Check our image format guide for detailed conversion advice.

How Much Does Image Format Affect Page Speed?

The impact is dramatic. Image format choice directly affects three key metrics.

Largest Contentful Paint (LCP). This measures when the biggest visible element loads. On most pages, that's an image. Using AVIF or WebP instead of JPG/PNG can cut LCP by 1-3 seconds on mobile connections.

Total page weight. Switching from PNG to WebP for all images typically reduces total page weight by 40-60%. For JPG to WebP, expect 25-35% reduction.

Time to Interactive. Smaller images mean less data to download. The browser finishes loading sooner. The page becomes interactive faster.

Real-world example: an e-commerce category page with 30 product photos.

Format	Total image weight	Load time (3G)
PNG	45 MB	30+ seconds
JPG (85%)	9 MB	8 seconds
WebP (85%)	6 MB	5 seconds
AVIF (80%)	4 MB	3.5 seconds

The difference between PNG and AVIF is over 10x. Even JPG to WebP saves 33% and shaves 3 seconds off mobile load times.

Google uses page speed as a ranking factor. Faster pages rank higher. Better image formats directly improve SEO.

What Quality Settings Should You Use?

Format alone isn't enough. Quality settings determine the balance between file size and visual sharpness.

For hero images and above-the-fold content: Use 85-90% quality. These images are large and visible. Quality matters here. The file size difference between 85% and 95% is small, so go higher.

For content images (in-article photos): Use 80-85%. These images are usually viewed at smaller sizes. The quality difference from 90% is invisible at typical viewing distances.

For thumbnails and grid layouts: Use 70-80%. Small images don't need high quality. At thumbnail size, compression artifacts are invisible. Save the bytes.

For background images behind text: Use 60-75%. These images are partially obscured. Lower quality is fine and can save 50%+ in file size.

One important rule: always start from the highest quality source. Converting a 60% quality JPG to WebP doesn't magically improve it. Use the best source file you have.

Do You Need to Support Old Browsers?

In 2026, the question is less about "if" and more about "how much effort."

WebP: 97%+ support. The 3% without support are on Internet Explorer or pre-2020 browsers. For most sites, a simple <picture> fallback covers these users.

AVIF: 93% support. The 7% gap is mostly older Safari versions and some mobile browsers. A WebP fallback handles these users well.

JPG and PNG: 100% support. Every browser ever made can display these.

The practical approach: serve modern formats with fallbacks. Modern users get small, fast images. Older browsers get larger but working images. Everyone sees something.

If your analytics show zero traffic from old browsers, you can skip fallbacks entirely. Just serve WebP. If you're cautious, add the <picture> element with JPG fallback. It's a few extra lines of HTML.

How Do You Convert Your Images to the Best Format?

ConvertIMG converts between all major formats. JPG, PNG, WebP, AVIF, TIFF, GIF, SVG, and HEIC. Everything runs in your browser. No uploads. No sign-up.

Drop your images in, pick the target format, set your quality, and download. Batch conversion handles entire folders at once. Your images stay on your device the whole time.