Compress JPG or Convert to WebP
Start at 20% quality or set a target file size · Up to 20 files · No uploads
100% In-Browser · Files Never Leave Your DeviceQuality
The default method starts at 20% for a fast first result. Raise it when you want more detail.
Target File Size
Use a maximum KB size when a website or form gives you a strict upload limit.
JPG or WebP
Press Compress JPG or Convert to WebP to start. Compare the result before you download it.
100% Private
Image processing happens in your browser. Your files are never uploaded.
Make a JPG smaller without sending it to a server
Have a photo that's too large for a form, an email, or your website? Start with the default 20% quality for a fast first result, add the photo, and press Compress JPG. Choose Target File Size instead when the destination gives you a strict KB limit. CompJPG keeps the original on your device and creates a separate download. It accepts JPG, PNG and WebP files, up to 30 MB each and 20 files per batch.
∿ Featured article The Beautiful Mathematics Behind Every JPEG How a 200-year-old idea about heat became the cosine transform inside every photo you take. Watch an image assemble itself from waves. Read the story →Start with the limit you actually need
For a form, use the maximum stated by that form. For a website, choose a size that looks good at the image's displayed dimensions. A smaller number isn't always a better result.
- 20KB, 50KB, 100KB and 200KB size guide — which dimensions fit each limit, with one-click presets.
Check the picture, not just the file size
Use the comparison slider and 100% zoom to inspect text, faces, and fine edges. Press Undo — restore original if you want to clear the result and try again. You don't need to add the same file twice. Both action buttons always process the original.
JPEG compression can discard detail; it isn't a guarantee of unchanged quality. If a target is too small, CompJPG shows a warning. It preserves pixel dimensions by default. You can set a maximum dimension or allow resizing in Target File Size mode. Our guide to reducing image size while keeping useful detail explains the trade-offs.
JPG or WebP?
Keep JPG when the destination requires it. For a website that accepts WebP, try Convert to WebP and compare the result. WebP isn't always the smaller option. Read the JPG to WebP guide or our JPEG, PNG, and WebP comparison before choosing.
Working on something specific? See the passport and ID photo checklist or tips for sharing photos by email and WhatsApp.
Frequently Asked Questions
Is CompJPG really free?
Yes, completely free with no sign-up, no payment, no hidden charges, and no limit on the number of compressions you can perform.
Are my images uploaded to a server?
No. All compression runs entirely in your web browser using JavaScript and WebAssembly. Your images never leave your device — we have zero access to your files.
How many images can I compress at once?
You can process up to 20 JPG, PNG or WebP images in a single batch. Each file can be up to 30 MB. Output is JPG or WebP; transparent areas become white.
What's the difference between Quality mode and File Size mode?
Quality is the default and starts at 20% for a fast first result. Raise the percentage if you want more detail. Target File Size searches for the best quality within your chosen KB limit and warns if the image cannot fit at its current dimensions. Dimensions stay unchanged by default. Set a maximum dimension or enable optional resizing to make smaller images. Both methods work for JPG and WebP output.
Will compression reduce my image quality?
JPG and WebP compression can both be lossy, so some quality reduction is expected. Moderate settings often make files much smaller while looking nearly identical. Use the before/after comparison and zoom controls to check fine details.
What browsers are supported?
All modern browsers — Chrome, Firefox, Edge, Safari, Opera, and Brave on desktop and mobile. CompJPG requires JavaScript and WebAssembly support.
Can I convert JPG to WebP?
Yes. Add JPG, PNG or WebP files, choose Target File Size or Quality, then press Convert to WebP to start. Download a .webp file or a batch ZIP. Transparent areas become white.
Can I undo compression and try different settings?
Yes. Press Undo — restore original to clear the result and keep the original loaded. For a batch, undo one image or all images. Change the file size or quality, then press either action button to try again.
How does the before/after slider work?
When you load a single image and compress it, a drag slider appears showing the original on one side and the compressed version on the other. Drag the handle left and right to compare quality in real time.