FineDocs

Convert JPG to WebP

Convert JPG photos to WebP in your browser and cut page weight without a visible quality drop. Nothing is uploaded and no watermark is added.

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WebP at 80 usually matches JPEG at 90. Going above 90 spends bytes for almost nothing.

Results appear here. Nothing is uploaded.

    How it works

    The JPEG is decoded by createImageBitmap, painted onto an OffscreenCanvas in a Web Worker, and handed to the WebP encoder built into your browser. That encoder is libwebp, the same library Google ships in Chrome, so the output is a standard lossy VP8 bitstream. No wasm module is downloaded, which is why the first conversion starts immediately rather than after a codec transfer.

    Measured results

    These figures come from running this exact tool over a fixed set of sample files on every build, not from an estimate.

    Sample fileSettingsBeforeAfterChange
    photo-gradient.jpgquality 80504 KB265 KB−47%
    photo-gradient.jpgquality 90504 KB461 KB−8%

    Benchmark run 2026-08-01.

    What to watch out for

    This is a second lossy pass, not a re-wrap

    Your JPEG has already thrown away detail that no format can recover. Encoding those surviving pixels as WebP discards a little more, and the damage compounds if you later convert the result again. Convert from the original whenever you still have it.

    Sharp colour edges can smear

    Both JPEG and WebP store colour at half resolution horizontally and vertically, so a thin red line on white already lost precision and is sampled again here. Screenshots with coloured text suffer most; photographs almost never show it.

    The browser encoder has one dial, not twenty

    A command-line libwebp build exposes method, segments, filter strength and near-lossless mode. Through the canvas only quality is reachable, so a dedicated encoder can beat this by a few percent at identical visual quality.

    Limits

    Files up to about 50 MB work reliably. Beyond that, the ceiling is your device's memory rather than any rule we impose — the work happens on your own machine. Tested in Chrome 140, Firefox 143, Safari 18.

    Why WebP is usually smaller than JPEG

    JPEG was finalised in 1992 and its compression is built around one idea: split the image into 8×8 blocks and describe each block with cosine waves. WebP, which arrived in 2010, borrows from video encoding instead. It predicts each block from the pixels already decoded around it and stores only the difference between the prediction and reality.

    That difference is usually tiny, and tiny numbers compress well. In practice a photograph saved as WebP at quality 80 lands close to a JPEG at quality 90 while being noticeably smaller. The gap widens on images with large smooth areas, because prediction is nearly perfect there, and narrows on noisy textures like foliage or film grain, where there is little to predict.

    When converting is worth doing

    The honest answer is: when the file is going onto a web page. Every browser released since 2020 displays WebP, so the compatibility argument that used to count against it has expired, and smaller images make pages load faster on the slow connections where it matters most.

    It is worth doing far less often for archival or for handoff. If you are sending a photograph to a printer, to a client, or into an editing pipeline, the extra lossy pass buys nothing and costs a little quality. Keep the original in those cases, and convert only the copy that ships.

    Quality settings that actually mean something

    The quality number is not a percentage of anything, and the same value means different things in different formats. WebP at 80 is roughly the point where differences stop being visible at normal viewing distance on a photograph. Below about 60 you start to see blockiness in gradients such as skies. Above 90 the file grows quickly for changes almost nobody can perceive.

    Because everything runs on your own machine, trying three settings costs nothing but a moment: convert, look, adjust. There is no upload to repeat and no quota to spend.

    Your files never leave your browser. Last updated 2026-08-01.