Why convert PNG to WebP
PNG is a lossless format, which is exactly what you want while you are working and exactly what you do not want on a live website. Every pixel is stored faithfully, and the file is several times larger than it needs to be for a browser.
WebP was designed for that second job. It compresses the same image far more efficiently, keeps the alpha channel PNG relies on, and every current browser reads it.
The one that surprises people
You do not have to accept any quality loss to get the saving. WebP has a lossless mode, and it still beats PNG.
In our own testing a 2,057 KB photograph became a 1,194 KB lossless WebP — 58% of the size, with every subpixel identical. A piece of interface artwork went from 138 KB to 49 KB, again with nothing changed.
Is quality 100 actually lossless?
Most converters describe their top setting as “near-lossless”, which is a hedge. We checked properly.
How we verified it
A PNG was converted at quality 100, both files were decoded back to raw pixels, and every subpixel was compared. On an opaque photograph and on opaque artwork, not one differed.
At quality 95 the same comparison showed 55% of subpixels had changed. The gap between the two settings is not a matter of degree — 100 is a different compression mode entirely.
The one caveat, measured
On artwork with soft or antialiased edges there is a small exception worth stating plainly.
Testing a transparent logo at quality 100: fully opaque pixels — zero differences. Fully transparent pixels — zero differences. Partly transparent edge pixels — 303 of them shifted, by the sort of rounding step you would need a pixel inspector to find.
The same image at quality 95 altered 20,672 fully opaque pixels, with colour channels off by as much as 28. That is the difference between a rounding artefact and actual lossy compression.
What that means for you
If the image is a master file, a logo, or anything you will edit again, convert PNG to WebP at 100 and you have lost nothing. You simply have a smaller file.
Lossless is sometimes the smaller file
This one is genuinely counterintuitive, and no competing page mentions it.
Flat artwork fights lossy compression
On the interface artwork we tested, quality 90 produced a 56 KB file while lossless quality 100 produced 49 KB. The lossy setting was both worse looking and larger.
Lossy compression saves space by smoothing detail. Flat colour and sharp text have no detail to smooth, so the encoder spends bits fighting the hard edges instead. Lossless coding, which looks for repetition, is exactly suited to that kind of image.
The rule of thumb
Photographs: use a lossy setting. Logos, icons, screenshots, charts and UI exports: use lossless. Not as a quality preference — as the smaller file.
Transparency comes through intact
A PNG logo converted to JPG gains a solid background, because JPG has no alpha channel. WebP does, so nothing has to be painted in.
We confirmed it after conversion: the corner pixel of the WebP still reads alpha 0, and the centre reads 255. If you have transparent assets, this is the whole argument for choosing WebP over JPG.
If a destination genuinely demands a JPG, our PNG to JPG converter lets you choose what colour replaces the transparency instead of forcing white on you.
Choosing a quality setting
For photographs
Quality 82 is the default and lands at about a tenth of the PNG. In our test that was 214 KB from a 2,057 KB source — and notably smaller than the same image as a JPG at quality 85, which came to 272 KB.
Go to 90 if the image has broad gradients or skin tones where banding would show. Drop to 75 when page weight matters more than the last few percent of fidelity.
For everything else
Use 100. It costs you nothing and, as above, is often the smaller file anyway.
Where the saving actually shows up
The reason to convert PNG to WebP is almost always a website, and it is worth being specific about the benefit.
Page speed and Core Web Vitals
Images are usually the heaviest thing a page loads, and Largest Contentful Paint is frequently an image. Cutting a hero image from 2 MB to 200 KB moves that metric more than almost any other change you can make.
Mobile data and bounce rate
The visitors most affected are the ones on the slowest connections, which is also the group most likely to leave. A lighter page is not an abstract score — it is people who stay.
Storage and bandwidth bills
If you serve images at any volume, an 80–90% reduction shows up on the invoice. Converting an existing library of PNG assets in bulk is a one-off job with an ongoing return.
How to convert PNG to WebP here
The tool sits at the top of this page. Three things are worth knowing about it.
Paste works, and it is the fastest route
Copy an image anywhere and press Ctrl+V on this page. For one-off exports out of a design tool that beats saving to disk first.
Drag and drop and the file picker both work too, and you can keep adding files to a queue that is already there.
The quality control is in front of you, not hidden
Most converters bury this behind an Advanced link. Since quality 100 is the whole point of converting PNG to WebP for a lot of people, it sits in the main panel with Lossless as a one-click preset.
Batches download as a ZIP
Convert a folder of exports and take them all in one archive. Because the work happens on your machine there is no upload wait and no per-file limit.
Serving WebP on your site
Converting the files is the easy half. Getting browsers to use them is where sites go wrong.
Use a picture element if you still support old clients
The safe pattern is a <picture> with a WebP source and a PNG fallback, so anything that cannot read WebP quietly gets the original. In 2026 that fallback is rarely exercised, but it costs one extra tag.
If you have decided not to support pre-2020 browsers, a plain <img src="...webp"> is fine and simpler.
Keep the filenames and alt text
Renaming hero.png to hero.webp is a URL change. Update every reference, keep the alt text identical, and if the old URL was linked from elsewhere, redirect rather than leaving a 404.
Do not convert twice in the pipeline
If your CDN or framework already optimises images on the fly, converting PNG to WebP by hand first can mean the image is re-encoded again downstream. Check what your build already does before adding a manual step.
Measure the result, not the intention
Run the page through Lighthouse before and after. The number that should move is Largest Contentful Paint. If it has not moved, the heavy image was not the one you converted.
When you should not convert PNG to WebP
When the file is a master
Keep your PNG originals if they are the source of truth. Convert copies for the web. Lossless WebP is safe to round-trip, but the discipline of keeping masters in a format everything reads is worth more than the disk space.
When the destination will not read it
Some older desktop software, some print workflows and some upload forms still reject WebP. That is the mirror image of this page. If something has handed you a WebP that will not open, WebP to PNG keeps the transparency and WebP to JPG gives you the smaller file.
When the PNG is already tiny
A 3 KB icon does not need converting. The saving is real in percentage terms and irrelevant in absolute ones, and you have added a format to your build for nothing.
PNG vs WebP at a glance
| PNG | WebP | |
|---|---|---|
| Lossless mode | Always | Yes, quality 100 |
| Lossy mode | No | Yes |
| Transparency | Yes | Yes |
| Photograph size | Very large | About a tenth, lossy |
| Same image lossless | Baseline | Around 40–65% smaller |
| Browser support | Universal | Every current browser |
| Older desktop software | Universal | Patchy |
Working with iPhone photos instead? HEIC to WebP goes straight from the camera format, and HEIC to PNG is the lossless route.
Before you publish the files
Images exported from a camera or a phone can carry EXIF metadata — device, timestamps, sometimes GPS coordinates — and publishing them puts that on your server for anyone to read.
You can remove EXIF data first without re-encoding the picture. It takes a moment and it is worth doing on anything user-submitted before it goes live.
Privacy: why this runs in your browser
The engine is WebAssembly executing on your own machine, so your PNG files are never uploaded and never queued on somebody else’s server.
That matters more here than on a consumer converter. The files people convert on this page are frequently client work, unreleased product screenshots or site assets under an NDA — exactly the material that should not be handed to a third party to process.
No retention policy, because there is nothing retained
Several converters for this format state that uploads are deleted after an hour or a day. That is a reasonable policy and it is still a policy: it describes what a company does with a copy of your file.
Here no copy exists. Convert PNG to WebP, close the tab, and the only files involved are the ones already on your disk.
It also makes the batch limits honest
A hundred files cost us nothing, because your processor does the work. There is no bandwidth to pay for, so there is no quota to invent and no premium tier to sell you.
The single trade is that the first conversion waits a moment while the engine loads. After that everything is local, and it keeps working if the connection drops halfway through a batch.