What is this calculator?
Converts a WebP image to JPEG in your browser, for the many tools and platforms that still do not accept WebP. JPEG has no alpha channel, so any transparent area is composited onto white — a deliberate, documented decision rather than a silent one.
Use it when:
- An upload form, printer, or application rejects WebP files.
- You are sharing an image with software that predates WebP support.
- You need the most universally readable image format available.
Intended for: Anyone who needs a WebP image accepted by software that does not support the format.
How is this calculated?
- The file you choose is read only for its type and name — nothing is uploaded, and the image itself never leaves your device.
- The tool validates that the source format is supported and that the requested output format and quality are valid together, producing a deterministic conversion plan: output format, quality, output file name, and the transparency and metadata policies that will apply.
- The output file name is derived from the source name with its extension replaced, so the result is predictable rather than randomly named.
- Your browser then decodes the image, draws it to a canvas at its original dimensions, and re-encodes it in the target format using its own built-in encoder.
- Because the image is decoded to raw pixels and re-encoded, the output carries only pixel data — embedded metadata such as EXIF is not preserved.
- Because JPEG has no alpha channel, the canvas is filled with white before the image is drawn, so any transparent pixels become white rather than an unpredictable colour.
Example
Converting `logo.webp`, which has a transparent background, to JPEG at quality 0.92.
- The canvas is filled white, then the image is drawn over it.
- The output name becomes `logo.jpg`.
Result: `logo.jpg` at quality 0.92, with the previously transparent background now white.
Frequently asked questions
Why did my transparent background turn white?
JPEG cannot store transparency at all. Rather than leave the result to chance, the tool composites transparent pixels onto white. If you need the transparency, convert to PNG instead.
Does converting WebP to JPEG lose quality?
Yes, twice over. The WebP was already lossily compressed, and re-encoding as JPEG compresses the decoded pixels again. Use a high quality setting and avoid repeated round trips.
What does the quality setting actually do?
It controls how aggressively a lossy encoder discards detail. Values around 0.8 to 0.92 are usually indistinguishable from the original at a fraction of the size; below about 0.7, compression artefacts become visible around edges and in flat areas.
Is my image uploaded anywhere?
No. The image is decoded and re-encoded by your own browser. It is never transmitted to a server, and nothing is stored after you leave the page.
Assumptions
What this calculator takes as given:
- Conversion happens entirely in your browser; the image is never uploaded to or stored on a server.
- Pixel dimensions are preserved exactly — the tool changes the format, not the size.
- The quality setting applies only to lossy encoders (JPEG and WebP); PNG is always lossless.
- Encoding uses your browser's own image encoder, so the exact output bytes can differ slightly between browsers.
- Transparent pixels are composited onto a white background.
Limitations
What this calculator cannot know or does not model:
- Metadata such as EXIF, GPS coordinates, and colour profiles is not carried over — useful for privacy, but a loss if you needed it.
- Resizing, cropping, rotation, and other edits are outside the tool's scope.
- Animated images are converted as a single still frame.
- Very large images may exhaust browser memory, since decoding happens in the page.
- The final file size depends on your browser's encoder and cannot be predicted before encoding.
- Transparency cannot be preserved, because JPEG has no alpha channel.
- Re-encoding an already-lossy image compounds compression loss.