Converting a JPEG to WebP and describing the result as lossless, when the detail JPEG discarded is already gone.
File formats
WebP
Also called .webp or webp image. Here is what it means, when it changes what you export, and what people get wrong.
File formatsRuns on your deviceUpdated 10 August 2026
The short answer
WebP is a web image format developed by Google and specified in IETF RFC 9649. It handles lossy compression, lossless compression, alpha transparency and animation in one file type, and typically produces smaller files than JPEG or PNG at comparable visual quality.
Updated
The short version
WebP at a glance
| Quick fact | Detail |
|---|---|
| Specification | IETF RFC 9649 |
| Modes | Lossy (VP8) and lossless (VP8L) |
| Transparency | Yes, 8-bit alpha in both modes |
| Animation | Yes, multi-frame with per-frame timing |
| Bit depth | 8 bits per channel |
| Maximum size | 16,383 x 16,383 pixels |
Slide the table sideways to see every column.
What makes WebP different from JPEG and PNG?
JPEG does lossy photographs. PNG does lossless graphics and transparency. GIF does animation badly. WebP does all three, which is the actual reason it caught on rather than any single compression figure.
Under the surface it is a RIFF container holding one of two codecs. Lossy WebP uses VP8 intra-frame coding, the still-image half of a video codec, which brings block prediction techniques that JPEG's 1992 design does not have. Lossless WebP uses VP8L, a different algorithm built around colour transforms, local palettes and backward references. An encoder picks one, and both live behind the same .webp extension, so you cannot tell from the filename whether a given file is lossy or lossless.
How does WebP handle transparency?
Both modes support an 8-bit alpha channel, which means soft, feathered edges rather than the hard on-off transparency GIF is limited to.
The interesting part is how lossy WebP does it. The colour data is compressed lossily, but the alpha channel is stored in a separate chunk and compressed losslessly. You get a photographic interior at photographic file sizes with a cut-out edge that stays clean. That combination is the practical argument for WebP over PNG for cut-out product images: a transparent PNG of a photographed object is large because PNG has to store the photograph losslessly too, whereas lossy WebP only pays full price for the mask.
Where does WebP fall short?
It is a delivery format, not an archive format, and the limits reflect that.
- Eight bits per channel only. No 10-bit, no HDR, no wide-gamut headroom. AVIF is the format to reach for if you need those.
- Lossy mode is 4:2:0 only. Colour resolution is always halved in both directions, which can soften saturated red or blue edges and fine coloured text.
- Maximum 16,383 x 16,383 pixels. Generous for the web, restrictive for large-format scans.
- No CMYK and limited support in prepress and desktop publishing tools, so it is a poor handoff format for print.
The compression advantage is also not uniform. At low and moderate quality WebP usually beats JPEG comfortably; at very high quality the gap narrows, and on some detailed images a well-tuned JPEG encoder matches it.
Can you upload WebP to selling platforms?
It depends on the platform, and this is worth checking rather than assuming. Shopify lists WebP among its accepted product media types and supports animated WebP as well, alongside its general limits of 5000 x 5000 px or 25 megapixels and files under 20 MB. Other marketplaces are more conservative, and several still specify JPEG or PNG in their catalogue requirements. Meta's catalogue image requirements, for instance, ask for JPEG or PNG.
The safe pattern is to keep a lossless master, publish WebP where the platform supports it, and export JPEG for everything else. Converting between the two is quick, and a converter that runs the encode locally in the browser, as Photomop's does, keeps the original off any server while you do it.
What people get wrong about webp
Each one is a real failure mode, not a style preference.
Sending WebP files to a print shop or a client whose software cannot open them.
Assuming every WebP is small; a lossless WebP of a photograph is as large as a PNG of the same photograph.
Using animated WebP for long clips, where an actual video file would be a fraction of the size.
Questions people ask
WebP, answered
The follow-up questions people search for once they have the definition.
Is WebP better than JPEG?
For web delivery, usually yes. At the same visual quality a lossy WebP is normally smaller, and it can also carry transparency and animation, which JPEG cannot. For compatibility with older software, print workflows and marketplace uploads, JPEG is still the safer choice.
Does WebP support transparent backgrounds?
Yes, with a full 8-bit alpha channel, so edges can fade smoothly rather than being cut hard. In lossy WebP the alpha channel is compressed losslessly even though the colour data is not, which keeps cut-out edges crisp at a small file size.
Why can I not open a WebP file on my computer?
Older versions of desktop editors and viewers predate WebP support. Current versions of the major operating systems and browsers handle it, but if a particular application refuses, converting to PNG or JPEG first is faster than hunting for a plug-in.
Should I convert my whole photo library to WebP?
Not as a replacement for your originals. WebP is 8-bit and lossy by default, so converting archives loses editing headroom you cannot get back. Convert copies for publishing and keep the camera files or lossless masters untouched.
Is WebP lossless or lossy?
Both, depending on how the file was encoded. The extension does not tell you which. Lossless WebP reproduces the exact pixels and is typically smaller than the equivalent PNG. Lossy WebP discards detail like JPEG does and is much smaller again.
Same cluster
More from the glossary
Neighbouring entries, so every term in the set is one hop from every other.
White background
A white background is a product-photo backdrop with no colour or detail behind the item.
WebGPU
WebGPU is a W3C standard that gives web pages direct access to modern graphics hardware, for both rendering and general-purpose compute.
White balance
White balance is the adjustment that makes neutral things look neutral under whatever light you shot in.
From the studio
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Sources
Where the facts on this page come from. Every link opens the specification, standard or documentation the claim was read at.
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