Every image format is a bet on a trade-off. WebP (Web Picture format by Google), introduced in 2010 by Google, bets on 25-35% smaller than JPEG, supports transparency and animation. Whether that bet pays off depends entirely on what you're doing with the file.
The technical shape of WebP
WebP stands for Web Picture format by Google. It is a lossy and lossless format built for modern websites, web optimization, progressive web apps.
The traits that matter day to day: transparency is supported, animation is supported, and software support in 2026 means over 96% of browsers in use in 2026 (caniuse).
On disk, the honest expectation: 25-34% smaller than an equivalent JPEG, per Google's published study.
Where WebP earns its keep
Reach for WebP when the job is modern websites, web optimization, progressive web apps — that is the territory the format was designed for, and where 25-35% smaller than JPEG, supports transparency and animation pay off.
Designers and developers tend to keep WebP in the toolkit for exactly these cases, and switch away the moment file size or compatibility starts to pinch.
When to use something else
The weak points — not supported in older browsers, limited editing software support — are real. For modern web delivery, WebP and AVIF compress dramatically harder; for maximum-compatibility sharing, JPEG still opens everywhere; for crisp graphics with transparency, PNG remains the default.
If you only remember one rule: photos lean lossy, graphics lean lossless, and the web leans modern.
Desktop alternatives exist for every step — Photoshop exports all of these, Squoosh tunes compression visually, TinyPNG squeezes the last kilobytes — but they all process one file at a time, which is the bottleneck on real libraries.
What this means for page speed
Images are usually the heaviest asset class on a page, so format choice flows straight into Largest Contentful Paint — the Core Web Vitals metric Google weighs for ranking. Lighter images, earlier paint, better scores: the chain is that direct.
Pair the format change with loading="lazy" on below-the-fold images and correct display dimensions, and the speed gain typically doubles.
Measure before and after with PageSpeed Insights — the image-weight line item makes the improvement concrete instead of theoretical.
A short history of WebP
The format was introduced in 2010 by Google, and the design goals of that era still explain its behaviour today — what it compresses well, what it ignores, and why certain software loves it.
Longevity is the underrated spec: a format that has survived this long has viewers, converters and documentation everywhere, which is precisely why it keeps getting used.
When something looks wrong
Colors shifted. Usually a color-profile story: the source carried a wide-gamut profile and the viewer assumes sRGB. Convert from an sRGB master when the destination is the web, and the shift disappears.
The file will not open. Nine times out of ten the viewer is the limitation, not the file. Try a second viewer before blaming the conversion, or convert to PNG — if that copy opens, the original was fine all along.
Transparent areas turned white. The target format has no alpha channel; flattening is the documented behaviour, not a bug. Re-convert to PNG or WebP if transparency must survive.
The file got bigger. Some content genuinely compresses worse in the new format — flat graphics in photo-oriented codecs, photos in graphics-oriented ones. The size readout before download is the early warning.
How the compression actually works
Dual-mode formats carry both toolboxes: a lossy mode for photographs and a lossless one for graphics. That flexibility is exactly why the modern web formats displaced single-mode ancestors.
Every recommendation here is downstream of those mechanics — formats do not have personalities, only algorithms.
WebP in real workflows
In practice the format clusters around modern websites, web optimization, progressive web apps — the places where its core strengths (25-35% smaller than JPEG, supports transparency and animation) are not nice-to-haves but requirements.
The friction shows up between tools, not inside them: not supported in older browsers, limited editing software support only becomes a real cost when the file needs to travel.
That is the honest shape of most format decisions in 2026: not better or worse, but native habitat versus the open road.
How to open WebP files
Compatibility questions almost always resolve to the viewer, not the file — here is the map per system.
Windows: the built-in Photos app handles common cases; GIMP and IrfanView are the free heavyweights, Photoshop the paid standard. If a WebP file refuses to open, the viewer — not the file — is usually the limitation.
macOS: Preview opens it natively, Quick Look previews it from Finder, and Affinity Photo or Pixelmator cover serious editing without an Adobe subscription.
Linux and everything else: GIMP and ImageMagick do the whole job from desktop or command line. And in a pinch, a browser converter doubles as a universal viewer: upload, convert to PNG or JPEG, open anywhere.
Converting WebP: the quick path
Out of WebP — for sharing, uploading or shrinking: drop the file on the converter, pick a universal target like JPEG or PNG, download. Dimensions stay identical; only the encoding changes.
Into WebP — when a workflow or platform demands it: the WebP converter accepts whatever you have and hands back the format the destination asked for.
Either direction takes seconds per file; the slow part of any conversion job is deciding, not converting.
Quick Answers
What is a WebP file used for today?
Mostly modern websites, web optimization, progressive web apps. That is the niche where its strengths — 25-35% smaller than JPEG, supports transparency and animation — actually matter, and where you will keep meeting the format in 2026.
Why is my WebP file so large?
Because of how the format stores data: 25-34% smaller than an equivalent JPEG, per Google's published study. If size is the problem, converting to a format with stronger compression is the direct fix — test one file and compare the readout.
Will browsers display WebP?
Support in 2026: over 96% of browsers in use in 2026 (caniuse). When a recipient or platform cannot handle it, converting to JPEG or PNG removes the question entirely.
Are WebP and Web Picture format by Google the same thing?
Yes — WebP is simply the short name for Web Picture format by Google. File extensions, MIME types and documentation use both interchangeably, which trips people up exactly once.
What is the best way to email a WebP file?
Check the size first: 25-34% smaller than an equivalent JPEG, per Google's published study. If the attachment pushes past a provider's limit (usually 20-25 MB), convert to a lighter format or share a link instead — recipients on slow connections will thank you either way.
Working with a WebP file right now? Run it through the converter and compare the before/after sizes — two minutes of testing beats an hour of reading.
Written by Giovanni Picaro, a web developer who has been building image tools and optimizing sites since 2019. Sources: MDN image format reference and Google web.dev. Last reviewed: 2026.