To reduce bounce rates, increase visitor retention, and improve ranking in Google, the speed of your website matters a lot. Most of the time, slow speed is caused by heavy images, and you will notice this in the report of a PageSpeed Insights audit. For a long time, most bloggers and developers used PNG as the default image format. I did that too, and eventually I switched to using WebP for most images on my site. Using PNG isn't a problem by itself; the problem is when you use this format everywhere, because it badly affects your site's performance.
To solve this exact problem, Google created WebP, a next-generation image format built for website speed. WebP is the best alternative to PNG because it creates a much smaller file, supports both lossy and lossless compression, and still supports transparent backgrounds.
Hey, welcome to BytebaseX. I'm Suptojit Modak, and in this post, I'm going to break down WebP vs PNG for website speed: which format is actually better for your site's loading time and performance. This is the first post in the Image Optimization series on BytebaseX. If you want to read the other posts, click here.
What Is PNG and Why Do People Still Use It?
PNG stands for Portable Network Graphics, and it's a format that keeps high quality and your design 100% intact. Before WebP existed, if you wanted a sharp screenshot or a logo with a clean transparent background, PNG was the only real option. That's why it became the default for so many of us in the first place, not because it was fast, but because it never let you down on quality.
Good Sides of PNG
- No quality drop: images in PNG format stay clear every time you save or share them anywhere.
- Clear background: good for logos, because you can make the background fully transparent.
- Sharp text: words and lines stay sharp and don't look blurry even when zoomed in.
The Problem With PNG
Because PNG keeps every detail and every bit of quality, the file size becomes very big. A single screenshot in PNG format can easily be 1 MB to 2 MB. If your article has 4 or 5 PNG images, your page will load very slowly on mobile phones. This is exactly the gap WebP was built to close.
What Is WebP and How Does It Fix This?
WebP is a modern image format built by Google to speed up the web. It reduces file size without making the photo look bad.
Good Sides of WebP
- Much smaller file size: WebP images are usually 30% to 50% smaller than PNG files.
- Good compression: it shrinks the image size, but the human eye can barely notice any loss in quality.
- Best of both worlds: it supports transparent backgrounds like PNG, but keeps the small file size closer to JPEG.
Google PageSpeed Insights always asks site owners to use WebP, because it helps pages load much faster. To see the actual numbers side by side, look at the table below.
| Feature | PNG | WebP | Result for Your Site |
|---|---|---|---|
| File Size | Large (500 KB – 2 MB) | Small (80 KB – 250 KB) | WebP makes your page much lighter. |
| Image Quality | Perfect (uncompressed) | Very good (compressed) | Hard to tell the difference visually. |
| Browser Support | Works everywhere | Works on 98% of browsers | Both work fine on modern devices. |
| Loading Speed | Slow | Fast | WebP improves site speed significantly. |
WebP vs PNG: Impact on Core Web Vitals and Page Speed
The table above shows WebP wins on file size, but the real reason this matters for website speed is Core Web Vitals. Serving images in WebP directly improves your Largest Contentful Paint (LCP) score. LCP measures how long it takes for the largest visual element on the screen, usually a featured image or hero banner, to finish loading. Replacing a 1.5 MB PNG featured image with a 150 KB WebP version can cut LCP rendering time by more than half.
How to Convert PNG to WebP for Your Website
Knowing WebP is better doesn't help much if you don't know how to actually switch. You have three practical options, depending on how many images you're dealing with.
Online Converters
Tools like Squoosh (by Google) or CloudConvert let you drag and drop a PNG and download a WebP version in seconds. This works well for one-off images or a handful of screenshots.
Bulk Conversion
If you already have hundreds of PNG images on your site, converting them one by one isn't realistic. Tools like ImageMagick (command line) or a plugin like ShortPixel (for WordPress) can convert entire folders at once.
Export Directly as WebP
Newer versions of Photoshop, GIMP, and Figma let you export straight to WebP, so you skip the PNG step entirely for new images.
For Blogger specifically, there's no built-in bulk converter. The practical approach is to convert images before uploading, using Squoosh or a similar tool, instead of uploading PNG and converting later.
Does WebP Work in Every Browser? WebP Browser Support in 2026
One thing that stops some people from switching is the fear that WebP won't display for every visitor. This concern was valid a few years ago, but it isn't anymore. As of 2026, WebP browser support covers around 98% of browsers in use, including Chrome, Firefox, Safari, and Edge. The remaining share is mostly very old browser versions that few real visitors are still using.
If you still want a safety net, especially for a business or e-commerce site, you can use the <picture> HTML element to serve WebP to browsers that support it, and fall back to PNG or JPEG automatically for the rest:
<picture>
<source srcset="image.webp" type="image/webp">
<img src="image.png" alt="description">
</picture>For most personal blogs and content sites, this extra step isn't necessary. Plain WebP is safe to use directly.
What About AVIF? Is WebP Still Worth Using in 2026?
If you've researched image formats recently, you've probably come across AVIF, a newer format that compresses even better than WebP, often 20% to 40% smaller at the same visual quality. So does that make WebP outdated already?
Not really, for a few practical reasons:
Encoding Speed
WebP encodes far faster than AVIF, which matters if you're converting images in bulk or on a low-power device.
Tooling Maturity
More editors, plugins, and platforms support WebP natively today. AVIF support is catching up, but it isn't as universal yet.
Good Enough for Most Content
For blog screenshots, thumbnails, and typical article images, the difference between WebP and AVIF file sizes is often too small to notice in real-world loading time.
The practical takeaway: WebP is still the right default for most bloggers in 2026. If you run an image-heavy site, like a photography portfolio or a large product catalog, AVIF is worth testing on top of WebP, since that's where the extra compression actually saves meaningful load time.
When Should You Use PNG vs WebP?
Despite WebP's clear speed advantage, PNG still has a few specific use cases where its uncompressed nature is required.
Stick With PNG When
- Designing website favicons or tiny source icons that require exact pixel alignment.
- Creating graphics for print or offline editing, where the raw source file quality must remain untouched.
- Handling edge cases where a specific legacy system lacks WebP decoding support.
Switch to WebP When
- Uploading blog post featured images, thumbnails, and inline visual content.
- Publishing technical screenshots that include code, charts, or UI elements.
- Managing product catalogs and gallery pages for e-commerce platforms.
Conclusion
PNG and WebP aren't really competing for the same job. PNG is for the cases where you can't afford to lose a single pixel: favicons, print files, and source graphics you'll keep editing. WebP is for everything a visitor actually loads on a live page: featured images, screenshots, thumbnails, and product photos. If your site is still running mostly on PNG, that's very likely the biggest reason your PageSpeed score isn't where you want it.
This is the kind of practical, no-fluff image optimization advice I want to cover on BytebaseX. This blog is where I write about things I've actually tested on my own sites, not just theory copied from somewhere else, and this WebP vs PNG comparison is part of that Image Optimization series.
