Convert JPG images to WebP for free, right in your browser — no sign-up, no upload.
JPG to WebP re-encodes a photo with WebP's lossy encoder, usually so a web page loads faster. On a 512 × 512 photo the 75,758-byte JPG became a 58,210-byte WebP at quality 92 — 23 % smaller, SSIM 0.9918 against the decoded JPG. It is a second lossy generation, so start from the best JPG you have and keep the JPG for places that do not accept WebP. Quality 100 gives a lossless WebP instead: exact, but 3.6 times the size of the JPG.
Drop image files hereProcess many files at onceNo upload · processed on this device
Making a game?
Nerulio is a 2D game asset studio first: draw pixel art, cut sprite sheets into animations, pack texture atlases, check autotile tilesets and export them for Godot, Unity, Phaser and other engines. It runs in your browser; files stay on your device.
Both formats are lossy but lose different things: JPG rounds 8 × 8 frequency blocks, lossy WebP predicts blocks from their neighbours and keeps colour at half resolution. When the input is already a JPG, the WebP encoder has to reproduce the JPG's artefacts as if they were detail, so the saving is smaller than when encoding from the original. MDN quotes lossy WebP at 25–35 % smaller than JPEG on average; this photo, already a JPG, saved 23 %.
The converter encodes once, at the slider's quality (default 92). It does not compare formats. If you want a byte limit or an automatic JPG-versus-WebP choice, compress scores both and keeps the better one.
Second generation
A lossy file made from another lossy file; the errors of both add up.
SSIM
Structural similarity, 1.0 = identical; used here to compare the WebP with the decoded JPG.
Quality 100 in Chromium
Switches to lossless WebP: exact pixels, much larger file.
The same JPG at two WebP settings (measured)
JPG made from the NASA fixture with Pillow at quality 92; Nerulio's converter code, Chromium 153, 2026-09-28.
Source: astronaut.jpg 75,758 bytes 512 x 512
-> WebP q92 58,210 bytes -23 % SSIM 0.9918
-> WebP q100 276,100 bytes +264 % lossless, identical pixels
From the original PNG instead:
WebP q92 59,824 bytes SSIM 0.9883 vs the PNG
If 23 % is not enough, lower the quality, or let compress to 50 KB decide: on this same JPG it chose a 44,435-byte JPG (SSIM 0.9822) over the WebP candidate, because the JPG scored higher.
What the WebP receives from the JPG
In the JPG
What the converter does
In the WebP
Decoded pixels
Encoded with lossy VP8 at the chosen quality
Approximate pixels, same width and height
EXIF orientation
Applied to the pixels while decoding
Upright pixels, no orientation tag
EXIF date, camera, GPS
Not copied
None
ICC profile
Drawn in the browser's sRGB canvas
sRGB ICCP chunk from Chromium
Check the result
Compare JPG and WebP side by side at 100 % on smooth areas (sky, skin): new banding or smearing means the quality is too low for this picture.
Check the byte counts; if the saving is only a few per cent, keep the JPG.
Load the WebP where it will be used (your site, CMS or app) to make sure it is accepted.
Troubleshooting
Symptom
Likely cause
How to check
Fix
The WebP is hardly smaller
The JPG was already strongly compressed; its artefacts cost WebP bits
Compare the sizes
Lower the quality to 80 or encode from the original photo instead of the JPG
The WebP is much bigger
Quality 100 writes lossless WebP
The quality slider shows 100
Use 92 or lower for photos
Colours look a little different
The output is tagged sRGB; a source tagged with another profile may shift
Check the source's colour profile in an image viewer
Export an sRGB JPG from the original first
Nothing appears on the site
The page or CMS does not accept WebP
Open the WebP directly in the browser
Serve the JPG, or keep both
Other ways to do it
Option
When it is the better choice
Keep the JPG
E-mail attachments, print services and older apps where WebP support is uncertain.
You have a size limit or want JPG and WebP compared by score before choosing.
Encode from the original
A camera original or PNG export avoids the second generation and saves more.
What this page does not cover
Every lossy re-encode adds error; there is no way to go JPG → lossy WebP without it.
EXIF (including GPS) is not copied; the WebP carries an sRGB profile.
Versions and sources
Measured on 2026-09-28 in Playwright Chromium 153 with Nerulio's converter path and, for the 50 KB comparison, src/compression.js with the compress task's options, on a JPG written by Pillow 12.3 (quality 92) from tests/fixtures/astronaut.png. The 25–35 % figure is MDN's, not ours.
Example generated with this tool. ZIP tools show their preview; inspect the downloaded archive for every file.
Convert image
Export PNG, JPG or WebP. JPG flattens transparency.
How it works
Open an image
Select PNG, JPG or WebP
Convert and download the new file
Supported formats
PNG / JPG / WebP / AVIF / HEIC → PNG / JPG / WebP — Input decoding and output encoding depend on browser support. Animated inputs are rejected; select a still frame first.
What this tool does
Re-encodes the image into the selected format rather than renaming its extension.
Implementation and verified quality
advanced · browser image codecs. Quality qualification is in progress. Pro/Flagship quality has not been established.
Before you export
JPG has no transparency. Canvas export does not promise preservation of metadata, color profiles or animation.
Frequently asked questions
Which format keeps a transparent background?
Choose PNG or WebP. JPG flattens transparency onto the selected background color.
Are my files uploaded?
This tool processes the files you open on your device without uploading them. Images you explicitly attach to community posts are uploaded separately. Optional engines and models are downloaded from third parties; those requests expose connection information such as your IP address.
Will my work be saved automatically?
No. Images and editing state stay in this tab; media output can use local temporary storage. Changing language preserves your work; reloading, closing the tab, or following a link to another page can clear it.
