To compress a WebP image, re-encode it at a lower quality, resize it to the dimensions you actually display, and strip metadata you don't need. The quickest route is a browser tool. Our Image Compressor handles JPG, PNG and WebP, and it works on your device, so the file is never uploaded. If you prefer the command line, Google's own cwebp encoder gives you full control. Both routes are covered below, along with the settings that matter and how WebP compares with JPEG.
TL;DR
- WebP is already efficient. Google's documentation says it is about 30% smaller than PNG and JPEG at equivalent visual quality, so you are squeezing an already compact format.
- Three levers do most of the work: the quality setting, the pixel dimensions and the metadata. Dimensions usually save the most.
- Quality numbers are not comparable between formats. Judge the result by eye and by file size, not by the number alone.
- For a no-install, no-upload option, use a browser-based image compressor that processes files locally.
- If a site or app rejects WebP, convert it to JPG instead of fighting the format.
Table of Contents
- What actually shrinks a WebP file
- Lossy or lossless: pick before you compress
- How to compress WebP images in your browser
- Quality settings that work in practice
- Command-line option: cwebp
- WebP versus JPEG: how much smaller is it really?
- Common mistakes when compressing WebP
- When WebP is the wrong file for the job
- Our perspective
- Compress your WebP files now
- A quick checklist before you publish or send
- FAQ
- Sources
What actually shrinks a WebP file
A WebP file gets smaller for only a few reasons. Knowing them keeps you from wasting time on settings that change nothing.
Fewer pixels. A 4000 by 3000 pixel photo shown in a 800-pixel-wide blog column carries about twenty-five times more pixels than the page can display. Resizing before you compress removes data the reader never sees.
Lower quality factor. WebP can be lossy or lossless. In lossy mode, a lower quality value discards more detail and produces a smaller file. Google's documentation notes that for the cwebp tool the default quality is 75, on a scale from 0 to 100, and that in lossy mode a smaller factor means a smaller file with lower quality.
Less metadata. Camera details, color profiles and editing history can ride along inside the file. Removing them trims a little, usually a few kilobytes, which matters most on small images like icons and thumbnails.
A better encoder effort. Some encoders can spend more time searching for a smaller result at the same visual quality. It costs encoding time, not image quality.
Lossy or lossless: pick before you compress
The first decision is which mode your image needs. Google explains that lossy WebP is based on VP8 key frame encoding, while lossless WebP uses a separate algorithm developed by the WebP team.
| Image type | Better mode | Why |
|---|---|---|
| Photographs, product shots, hero images | Lossy | Photos hide small losses well, and the savings are large |
| Screenshots with text | Lossless or high-quality lossy | Sharp edges around letters show artifacts quickly |
| Logos, icons, flat graphics | Lossless | Few colors and hard edges compress well without loss |
| Images with transparency | Either | WebP supports an alpha channel in both modes |
If you are not sure, start with lossy at a moderate quality and zoom in to 100% on the result. If you see blocky patches around text or smeared gradients, go up in quality or switch that image to lossless.
How to compress WebP images in your browser
For most people, a browser tool is the fastest way to get a smaller file, with nothing to install and no account to create. Here is the routine that works for blog images, product photos and school or work submissions.
- Check the current size. Note the file size and, if you can, the pixel dimensions. The image dimensions checker shows the pixel size so you know how oversized the file is.
- Resize first if the image is larger than it will be displayed. Use the image resizer to set exact pixels or a percentage. For a full batch, the bulk image resizer saves you from repeating the steps.
- Open the Image Compressor and add your WebP file. Everything runs locally in your browser, so your photo stays on your device.
- Compare before and after. Open both at 100% zoom and look at faces, text and smooth gradients such as sky.
- Save the smaller file and keep your original untouched in case you need to try a different setting.
If you handle several kinds of images in one go, the image preparation workflow groups resizing, compressing and converting in one place.
Why local processing matters for images
Many online compressors send your file to a server. That is fine for a stock photo, but less comfortable for an ID scan, a signed form, a screenshot with account details or unreleased product shots. Our tools process files in your browser without uploads, so these files never leave your machine. That also means no waiting on an upload and download on a slow connection.
Quality settings that work in practice
There is no universal "correct" quality value. Google's tool defaults to 75 for lossy output, and that is a sensible starting point. From there, adjust by eye.
A useful working method:
- Start at the default of 75 and check the result at 100% zoom.
- If the image looks clean, try a lower value and compare again. Stop one step before you see artifacts.
- If you see banding or blockiness, go up in steps of five.
- Use the first acceptable result, not the smallest possible one. A file that is 5% smaller but visibly worse is a poor trade.
Quality numbers do not transfer between formats
The number on the slider is not a measure of how good the picture looks. Ilya Grigorik of the Chrome team wrote on web.dev that quality 90 in JPEG gives a very different result than quality 90 in WebP, and that even the same format can look different depending on the compressor. So if you used 80 for your JPEGs, do not assume 80 will give the same look in WebP.
A 2026 benchmark from Cleanor Labs shows the effect in numbers. At a nominal quality of 80 on the Kodak test set, JPEG came out at 74.3 KB with an SSIM of 0.965, while WebP came out at 58.4 KB with an SSIM of 0.972. Same setting, different size, different actual fidelity. SSIM is a score for structural similarity to the original, where closer to 1 means closer to the source.
The takeaway: choose settings per format and verify by looking.
Command-line option: cwebp
Developers and anyone batch-processing a folder can use Google's cwebp encoder. The basic form is:
cwebp [options] input_file -o output_file.webp
The options that matter most for file size are these:
| Option | What it does |
|---|---|
-q | Quality factor from 0 to 100, default 75 |
-lossless | Encodes without any loss |
-near_lossless | Adjusts pixel values to help compressibility, typical value around 60 |
-m | Method from 0 to 6, default 4, trading encoding speed for file size and quality |
-preset | Parameter sets for default, photo, picture, drawing, icon or text |
-alpha_q | Alpha channel compression from 0 to 100, default 100 |
-size | Targets a specific output size in bytes |
-resize | Resizes the image while encoding |
-metadata none | Leaves out metadata |
-print_ssim | Reports the SSIM score so you can measure the result |
A few combinations worth knowing:
- Photo for the web: use
-qwith a value around the default, add-preset photo, and resize to display width. - Hard-edged graphic you want to keep exact: use
-lossless, or try-near_losslesswhen a tiny pixel change is acceptable and you want a smaller file. - A strict size limit, such as an upload cap: use
-sizeto aim at a byte target, then check the result visually. - Measuring instead of guessing: add
-print_ssimto compare settings numerically.
Raising -m makes the encoder work harder for a smaller file at the cost of time. On a handful of images the difference in time is trivial.
WebP versus JPEG: how much smaller is it really?
If you landed here wondering whether converting to WebP is worth it, the evidence is favorable but nuanced.
Google's study of its own format found that WebP files averaged 25% to 34% smaller than JPEG at equivalent SSIM. The ratios across the four test sets were 0.74, 0.72, 0.74 and 0.66. Google's gallery shows the same pattern with real files: a JPEG of 43.84 KB became a WebP of 29.61 KB, and a 297.05 KB JPEG became 198.38 KB, an overall saving of 32%.
Independent 2026 testing from Cleanor Labs agrees on clean test images: on the lossless Kodak set at SSIM 0.95, one image needed 55.5 KB as JPEG and 36.5 KB as WebP, a 34% reduction. The same report adds a useful caution: when re-compressing real 12-megapixel JPEG photographs at matched quality, WebP files came out 25% to 57% larger. Their explanation is that an existing JPEG is already a low bar to beat, because re-encoding JPEG to JPEG reuses the same transform and is unusually cheap.
What this means for you:
- Starting from a lossless or uncompressed source (PNG, a camera RAW export, a design file): WebP typically gives a clear saving over JPEG.
- Starting from an existing JPEG: do not assume a conversion will shrink it. Resize and compress first, then compare the two files and keep the smaller one.
- Always compare file sizes after conversion. The numbers in studies are averages. Your image is one specific case.
Common mistakes when compressing WebP
Compressing again and again. Each lossy pass throws away more detail. Always return to the original file and compress once with a better setting, rather than compressing a compressed copy.
Skipping the resize. Quality sliders cannot compete with cutting pixel count. Resize to the largest size you will actually display, plus some room for high-density screens.
Judging at zoomed-out view. Artifacts hide when an image is small on screen. Check at 100%.
Using one setting for everything. A photograph and a screenshot of a spreadsheet need different treatment. Group your images by type and use a different setting for each group.
Overwriting the original. Keep the source. You may need it for print, a different crop or a later round of changes.
When WebP is the wrong file for the job
WebP is well supported in modern browsers, but not every upload form, email client, print shop or older application accepts it. If you get an error such as "unsupported file type," the practical fix is to convert, not to keep re-saving. Our WebP to JPG converter turns it into a widely accepted JPEG, and the image converter handles PNG, JPG and WebP in either direction.
Students submitting scans often need a PDF instead. In that case, convert the images first and then use JPG to PDF to combine them into a single document. Compress the images before building the PDF, since the PDF's size mostly follows the size of the images inside it.
If an upload is blocked because the file is too big rather than the wrong type, our guide on fixing an image that is too large to upload walks through the options.
Our perspective
Most people who search for a WebP compressor do not want a project. They want one file, smaller, in the next minute, and they want to know where it went. That is why we built our tools to run in the browser: your image is processed on your device, there is no account to make and nothing to install.
We also think the order of operations matters more than any single setting. Check the dimensions, resize to what you will show, compress once from the original, and compare at full zoom. Our image tools are designed to sit side by side for exactly that sequence, so you can go from checking, to resizing, to compressing, to converting without switching sites.
Privacy is part of the job, not an extra. A screenshot, a scanned form or a product photo before launch should not have to travel to a stranger's server to lose a few hundred kilobytes. Our approach is to keep the work local and free to use, so a quick task stays quick.
IA
Compress your WebP files now
Open the Fixora Image Compressor, add your WebP, JPG or PNG, and save the smaller version. It is free, needs no account, and your files stay in your browser.
Need more than one step? The image tools collection brings resizing, compressing and converting together, and the full tool list covers PDFs, text, CSV and JSON as well.
A quick checklist before you publish or send
- Dimensions match the display size, not the camera's native size.
- The file was compressed once from the original.
- You checked the result at 100% zoom, including text and gradients.
- The file is smaller than the version you started with. If not, keep the original format or try a different one.
- The destination accepts WebP. If it does not, convert to JPG.
- Sensitive images were processed locally rather than uploaded.
FAQ
What is the best quality setting for compressing WebP?
There is no single best value, but 75 is a reasonable start because it is the default in Google's cwebp tool. Check the result at 100% zoom and move up or down in small steps. Quality numbers are not comparable between formats, so do not carry a JPEG setting over unchanged.
Can I compress a WebP image without losing quality?
Yes, with lossless mode, which encodes without any loss, though the saving is smaller than with lossy. For most photos, a moderate lossy setting looks the same to the eye at a much smaller size. Resizing to the display dimensions also cuts size without touching quality at the size you show.
Is WebP smaller than JPEG?
Usually, yes. Google's study found WebP files 25% to 34% smaller at equivalent SSIM. Results differ when the source is already a compressed JPEG, so compare file sizes after converting and keep whichever is smaller.
How do I reduce WebP file size without uploading the image?
Use a tool that processes files inside your browser, such as the Fixora Image Compressor. The image stays on your device throughout. Developers can also run cwebp locally from the command line.
What should I do if a website will not accept my WebP file?
Convert it to JPG or PNG. A WebP to JPG converter takes seconds, and you can compress the result afterwards if the site also has a size limit.
Sources
- cwebp | WebP | Google for Developers
- Compression Techniques | WebP | Google for Developers
- WebP Compression Study | Google for Developers
- WebP gallery | Google for Developers
- Choose the correct level of compression | web.dev
- Iso-Quality Storage Efficiency of JPEG, WebP, and AVIF | Cleanor Labs