PNG vs WebP: which one should you use

Side by side

Size and transparency figures come from Google's WebP documentation, which also states that lossy WebP with transparency is typically three times smaller than the equivalent PNG.

Where WebP wins

• Images on a page you own Every current browser displays WebP. A quarter off your image weight is a real speed gain on mobile connections.
• Transparent graphics with photographic content A logo over a photographic background is where lossy WebP with alpha pulls furthest ahead of PNG.
• Large screenshots and UI captures Flat colour and sharp text compress well in lossless WebP, so you keep exact pixels and lose the bulk.
• Anywhere bandwidth is the constraint Email newsletters, documentation sites, and image-heavy catalogues.

Where PNG is still right

Keep the PNG as the master copy. Convert a delivery copy. That single rule covers most of the cases below.

1. Files you will edit again Round-tripping through a lossy format degrades an image a little each time. A lossless master avoids the question entirely.
2. Print and design workflows Plenty of layout and prepress software still expects PNG or TIFF. Handing a printer a WebP invites an email you do not want.
3. Anything an old system opens Legacy internal tools, older document viewers, and some upload forms reject WebP outright.
4. Files you send to other people A colleague on an older machine may not be able to double-click it. That is the whole reason a WebP to PNG converter gets used.

Lossless or lossy WebP

WebP is two formats wearing one file extension. Lossless mode keeps every pixel exactly. Lossy mode discards detail the encoder judges you will not notice, and the file gets much smaller.

Choose lossless for logos, diagrams, screenshots, and anything with hard edges or text. Choose lossy for photographs and for backgrounds where nobody will zoom in. Text on a lossy setting picks up soft haloes around the letters, which is the artifact people notice first.

The Vaultaire converter offers both. In lossless mode it reads the new file back and blocks the download unless the output is really a lossless VP8L image whose pixels match. Alpha values must match exactly, with a tolerance of at most 2 per premultiplied 8-bit channel for partially transparent colour, because native browser encoders round those values.

What conversion does to metadata

Converting is also a way to drop what is attached to the file. The converter does not copy source EXIF, ICC, text, time, or C2PA records into the new WebP, then scans the finished file with an independent parser and keeps the download locked if any record turns up.

That matters when the PNG came from a phone screenshot, a camera export, or an image generator. If you want to see what is attached before deciding, the metadata inspector lists it. Everything runs in the browser worker, and the file is never uploaded.

Practical limits on the converter: one still PNG, up to 20 MB, 4,096 pixels on either side, and 16,000,000 total pixels. Animated PNG is rejected before decode rather than silently exported as its first frame.