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Reduce Page Size by more than 50% with WebP and AVIF

Reduce Page Size by more than 50% with WebP and AVIF

By Get Pronto•

In the fast-paced world of web development, loading speed is no longer just a nice-to-have—it's essential for user experience, conversion rates, and even SEO rankings. With images accounting for roughly 75% of the average webpage's total weight, optimizing your visual content represents the single most effective way to boost your site's performance.

While many developers still rely on traditional formats like JPEG and PNG, modern image formats offer dramatically better compression with similar or even improved visual quality. Two formats stand out in 2025: WebP and AVIF. This guide will show you how these formats can slash your page size by 50% or more, and how Get Pronto makes implementation a breeze.

Just how good are these formats?

Let's start with cold, hard data on how these formats perform compared to traditional options:

File size comparison at similar quality

Format Avg. Size Reduction vs. JPEG Avg. Size Reduction vs. PNG
WebP 25-34% 26%
AVIF ~50% 40-60%

These aren't just theoretical numbers. According to SpeedVitals' 2024 analysis, WebP images are typically 25-34% smaller than their JPEG equivalents at the same visual quality, while AVIF takes compression even further, delivering files approximately 50% smaller than JPEG.

A Google study comparing WebP with JPEG found consistent file size savings between 25-34% at equivalent Structural Similarity (SSIM) index values, which is a technical measure of perceived image quality.

For photographic content, AVIF generally outperforms WebP by an additional 20-30% in file size reduction while maintaining similar or better quality. Smashing Magazine's analysis shows that AVIF images can be up to ten times smaller than JPEGs of similar visual quality in some cases.

Performance and SEO benefits

These size reductions directly translate to measurable benefits:

  1. Faster Load Times: Smaller images mean faster downloads, particularly important for mobile users.
  2. Improved Core Web Vitals: Images are responsible for approximately 42% of the Largest Contentful Paint (LCP) element, a key Google ranking factor.
  3. Lower Bandwidth Costs: Serving smaller images reduces your CDN and bandwidth expenses.
  4. Better Mobile Experience: Mobile users with limited data plans will appreciate the reduced data usage.

A Cloudinary study found that implementing AVIF can lead to significant improvements in page speed scores, with some sites seeing their LCP times drop by hundreds of milliseconds—often enough to move from "needs improvement" to "good" in Core Web Vitals assessment.

Comparing WebP vs. AVIF

While both formats offer substantial improvements over legacy options, they have different strengths and considerations:

WebP: the mature option

Strengths:

Best For:

AVIF: the next-generation contender

Strengths:

Best For:

Browser Support: AVIF support has grown rapidly, with approximately 93.3% of global users on compatible browsers as of early 2025. All major browsers now support AVIF including Chrome, Firefox, and Safari. You can check current browser support statistics on Can I Use.

Image type considerations

Different image types benefit differently from these formats:

Implementation with Get Pronto

Here's where Get Pronto makes your life remarkably easier. Instead of managing multiple image versions and complex format detection logic, Get Pronto handles the conversion and delivery automatically.

1. Simple URL-based format conversion

With Get Pronto, you can convert any image to WebP or AVIF simply by changing the file extension in the URL:

Original: https://api.getpronto.io/your-account/images/photo.jpg
WebP: https://api.getpronto.io/your-account/images/photo.webp
AVIF: https://api.getpronto.io/your-account/images/photo.avif

This makes it incredibly simple to serve the optimal format to each browser.

2. Format-based optimization

Get Pronto doesn't just change the file extension – it intelligently optimizes the image specifically for each format's strengths. This means your WebP and AVIF versions are truly optimized, not just basic conversions.

3. Responsive images with modern formats

For the best experience, you can combine responsive sizing with modern formats using Get Pronto's URL parameters:

<picture>
  <source 
    srcset="https://api.getpronto.io/your-account/images/hero.avif?w=1200 1200w,
            https://api.getpronto.io/your-account/images/hero.avif?w=800 800w,
            https://api.getpronto.io/your-account/images/hero.avif?w=400 400w"
    type="image/avif">
  <source 
    srcset="https://api.getpronto.io/your-account/images/hero.webp?w=1200 1200w,
            https://api.getpronto.io/your-account/images/hero.webp?w=800 800w,
            https://api.getpronto.io/your-account/images/hero.webp?w=400 400w"
    type="image/webp">
  <img 
    src="https://api.getpronto.io/your-account/images/hero.jpg?w=800"
    alt="Hero image"
    loading="eager"
    width="100%"
    height="auto">
</picture>

This code serves:

Implementation best practices

To maximize the benefits of modern image formats:

  1. Use format negotiation: Either use the <picture> element as shown above or content negotiation via the Accept header. Jake Archibald's guide offers excellent examples of implementation approaches.

  2. Consider image content: For photographs, prioritize AVIF > WebP > JPEG. For graphics with text or simple illustrations, try WebP first, then fall back to PNG or SVG as appropriate.

  3. Combine with responsive images: Always serve appropriately sized images alongside optimal formats.

  4. Monitor quality: When converting to WebP or AVIF, use quality settings that maintain visual integrity while maximizing compression. With Get Pronto, you can adjust quality with the ?q= parameter.

  5. Test real-world performance: Measure before-and-after loading metrics to quantify the improvements.

E-commerce product page optimization

Let's look at a real-world example of how modern formats can transform performance:

An e-commerce client was using high-quality JPEG product images averaging 280KB each, with 8-12 images per product page. By implementing AVIF with WebP fallbacks via Get Pronto:

This demonstrates how significant the real-world impact can be, especially for image-heavy sites.

Getting started with Get Pronto

Ready to implement these powerful formats on your own site? Get Pronto makes it simple:

  1. Sign up for a Get Pronto account (free tier available)
  2. Upload your high-quality original images through our dashboard or API
  3. Transform images on-the-fly with simple URL parameters
  4. Deliver optimized images through our global CDN

Our TypeScript SDK makes implementation even easier:

import GetProntoClient from "getpronto-sdk";

// Initialize the client with your API key
const client = new GetProntoClient({
  apiKey: "YOUR_API_KEY"
});

// Upload an image
const uploadResult = await client.files.upload("./product-photos/camera.jpg");

// Generate AVIF and WebP URLs
const avifUrl = client.transform.format(uploadResult.url, "avif");
const webpUrl = client.transform.format(uploadResult.url, "webp");
const jpegUrl = uploadResult.url; // Original as fallback

console.log(`AVIF: ${avifUrl}`);
console.log(`WebP: ${webpUrl}`);
console.log(`JPEG: ${jpegUrl}`);

Conclusion

Modern image formats like WebP and AVIF represent one of the most effective performance optimizations available to developers today. With file size reductions of 25-50% or more compared to traditional formats, they can dramatically improve loading times, user experience, and even SEO rankings.

While implementing these formats historically required complex workflows and browser detection logic, Get Pronto makes it trivial with simple URL-based transformations and a powerful global CDN.

Ready to see how much smaller your site can get? Sign up for Get Pronto today for free and experience the future of image optimization.

Tags

OptimizationImages