UtilibyWritten by the Utiliby editorial team · Last updated October 13, 2026 · Rules and formulas reviewed October 2026
What this free image compressor does
Pictures are the heaviest part of most web pages and emails. A single phone photo is often 3 to 8 MB, which is too big for an email attachment limit, a job-application form or a fast mobile page. An image compressor makes the file smaller by storing the picture more efficiently, usually with changes your eyes cannot see at normal size.
This free online tool compresses JPG, PNG and WebP images directly in your browser. You can set a quality level or a target file size in KB, reduce the width if you want, choose the output format, and see a before-and-after slider so you can judge the result yourself. Nothing is uploaded, there is no limit on the number of images, and there is no watermark.
How to compress an image in four steps
- Add your images. Drag them onto the drop area or click it to choose files. You can add many at once.
- Choose the settings. Leave the format on Same as input, or switch to WebP for smaller files. Set the quality, or type a target size in KB.
- Check the result. Each row shows the old size, the new size and the saving. Press Compare to drag a slider between the original and the compressed version.
- Download. Save one image, or press Download compressed images to get them all in one ZIP.
JPG, PNG or WebP: which format compresses best?
| Format | Compression | Transparency | Best for |
|---|---|---|---|
| JPG | Lossy, small for photos | No | Photographs, email, general use |
| WebP | Lossy or lossless, about 20-35% smaller than JPG | Yes | Websites and apps |
| PNG | Lossless, large for photos | Yes | Screenshots, logos, graphics, text |
The biggest saving usually comes from picking the right format, not from the quality slider. A photo saved as PNG can be ten times larger than the same photo as JPG. A screenshot with flat colors and text, on the other hand, is often smaller as PNG than as JPG and looks sharper. When you are unsure, leave the format on Same as input and look at the result.
Choosing a quality level
JPG and WebP quality runs from 1 to 100, but the scale is not linear. Going from 100 to 80 usually removes more than half the file size with almost no visible change, while going from 50 to 30 changes the look a lot for a small extra saving.
| Quality | Typical result | Use it for |
|---|---|---|
| 90 to 100 | Very large, near original | Archive copies, large prints |
| 75 to 85 | Small, looks the same on screen | Websites, social media, email |
| 55 to 70 | Smaller, slight softness | Thumbnails, galleries, previews |
| Below 50 | Visible blocks and blur | Only when size matters most |
Check the result at the size people will actually see it. A picture that looks soft when you zoom to 300 percent may look perfectly good at the size it is displayed.
Compressing to a target size such as 100 KB or 50 KB
Many forms, portals and exam sites set strict limits: a photo under 100 KB, a signature under 50 KB, a document scan under 200 KB. Type the number in the Target size box and the tool does the searching for you. For JPG and WebP it finds the highest quality that fits under the limit. For PNG it reduces the number of colors step by step.
If a limit is too small even at the lowest quality, the tool also shrinks the pixel dimensions in small steps until the file fits, and tells you the result. If the dimensions matter too, set a Max width yourself first. Target sizes are approximate in the sense that the result will be at or under the number, not exactly equal to it.
Image size, page speed and SEO
Images are commonly more than half of the bytes on a web page. Large images slow down the Largest Contentful Paint, one of Google's Core Web Vitals, and that can affect how your pages feel and how they are measured. The usual advice has three parts:
- Resize to the display size. An image shown 800 pixels wide does not need to be 4000 pixels wide.
- Compress. Quality 70 to 80 is usually enough for the web.
- Use modern formats. WebP offers smaller files than JPG at similar quality and is supported by all current browsers.
Descriptive file names and alt text also help search engines understand an image, but those are separate from compression.
Common uses
- Email attachments: get under the size limit of your mail provider.
- Job, visa and exam forms: meet limits such as 100 KB or 200 KB.
- Websites and blogs: speed up your pages before you upload images.
- Online shops: keep product photos light so listings load fast on phones.
- Messaging and social posts: send photos that upload quickly on a slow connection.
- Backups and storage: free up space when you keep many photos.
What gets removed: metadata and orientation
The tool draws each image onto a canvas and saves it again. That process drops the hidden information stored in the file: camera make and model, date and time, software, and GPS location. For most people that is a bonus, because photos shared online can reveal where they were taken. The picture's orientation is applied before saving, so it still appears the right way up. If you need to keep metadata, use the original file or a metadata-preserving editor.
Troubleshooting
- The file did not get smaller: it may already be well compressed, and the tool keeps your original. Try a lower quality, WebP, or a smaller Max width.
- PNG is still large: use fewer colors, or switch a photo to JPG or WebP.
- Colors look banded: in PNG, raise the number of colors or switch on smooth gradients.
- An image failed to open: HEIC photos open only in Safari. Convert them to JPG first.
- It stops on a huge photo: some phones cannot handle more than about 16 megapixels. Set a Max width to shrink it.
Online compressor or desktop software?
Desktop programs and command-line tools such as mozjpeg or Squoosh offer finer encoder settings and can squeeze out a little more. Services like TinyPNG are convenient but limit free use to a set number of files and a maximum size per file, and they upload your pictures. A browser tool is fastest for everyday jobs, handles many files at once and keeps your images private. For a hero image on a high-traffic site, an extra round of manual tuning may be worthwhile.
Privacy and how it works
Your browser opens each file and draws it onto a canvas. For JPG and WebP it uses the browser's built-in encoder at the quality you pick. For PNG, the page reduces the palette with a median-cut method and writes the file itself using the browser's compression. None of this involves a server, and the page does not store, log or analyze your pictures.
Frequently asked questions
How do I compress an image online for free?
Drop one or more images into the tool above, leave the quality at 75 or pick your own, and wait a moment. Each image shows its old and new size. Press Download for one image, or Download compressed images to get a ZIP. Everything happens in your browser.
Are my images uploaded to a server?
No. The images are opened and re-encoded on your own device using your browser. Nothing is sent to Utiliby or anyone else, and it keeps working if you go offline after the page has loaded.
What quality setting should I use?
For photos, 70 to 80 is the sweet spot: files are often 70 to 90 percent smaller and still look clean. Use 85 to 90 for images you will print or zoom into, and 50 to 60 for small thumbnails. Below about 40, blocky artifacts become visible.
How do I compress an image to 100 KB?
Type 100 in the Target size box. The tool searches for the highest JPG or WebP quality that stays under 100 KB. If even the lowest quality is too big, it shrinks the dimensions in steps until it fits. The same works for 50 KB, 20 KB or any other limit.
What is the best format: JPG, PNG or WebP?
JPG suits photos and is accepted everywhere. WebP is typically 20 to 35 percent smaller than JPG at similar quality and supports transparency, and all current browsers can show it. PNG is lossless and best for screenshots, logos and graphics with flat color or transparency.
Why did my PNG barely get smaller?
PNG is a lossless format, so it only shrinks if you reduce colors. Choose 256 or fewer colors for graphics and screenshots, which often cuts the size by half or more. Photos saved as PNG are very large; converting them to JPG or WebP saves far more.
Does compressing reduce the image dimensions?
No, not unless you set a Max width or the target size is too small to reach otherwise. By default the pixel width and height stay the same and only the data used to store each pixel changes.
Will it damage the image quality?
JPG, WebP and reduced-color PNG are lossy, so some detail is discarded. At quality 75 the change is hard to see on a normal screen. Use the Compare slider to check before and after, and keep your original file in case you need full quality later.
Can it compress many images at once?
Yes. Drop as many images as you like. They are processed one after another, and you can download them together in a single ZIP file or each one by itself.
Is there a file size or number limit?
There is no set limit. Very large photos need more memory, and some phone browsers cannot process images above about 16 megapixels. If an image fails, use the Max width box to shrink it first.
Does it remove EXIF data and GPS location?
Yes. Images are redrawn and saved fresh, so camera details, dates and GPS location are not carried over. That is a privacy benefit. The orientation is applied, so photos still show the right way up.
Why is the compressed file sometimes not smaller?
If an image is already well compressed, saving it again can make it the same size or larger. In that case the tool keeps your original file and tells you so, rather than giving you a worse result.
Can I compress a GIF or BMP?
You can load them, and the tool converts them to JPG, WebP or PNG. Animated GIFs are not kept animated; only the first frame is saved, so use a GIF tool for animations.
Will compression help my website speed and SEO?
Yes. Images are usually the heaviest part of a page, and lighter images improve loading speed and Core Web Vitals such as Largest Contentful Paint, which search engines consider. Resize images to the display size too, not just compress them.
Is the transparent background kept?
Yes for PNG and WebP. JPG has no transparency, so transparent areas are filled with white when you save as JPG.
Can I use the compressed images commercially?
Compressing does not change who owns the image or what rights apply to it. You can use the compressed copy under the same terms as the original. The tool adds no watermark.
What can I print or save from the page?
Print / save summary gives a clean table of file names, original and new sizes, the percentage saved and your settings. Copy summary copies the same table as text. The images themselves are the main download.
Sources and further reading
- web.dev (Google), Optimize your images and Largest Contentful Paint, for guidance on image size and Core Web Vitals.
- MDN Web Docs, Image file type and format guide, for the differences between JPEG, PNG and WebP.
- W3C, Portable Network Graphics (PNG) Specification, for how PNG stores palettes and compresses data.
- Google Developers, WebP documentation, for lossy and lossless WebP compression.
- ITU-T T.81 / ISO/IEC 10918-1, the JPEG standard that defines lossy image compression.
Sources were consulted in October 2026. Standards and rules can change, so always check the official page for your situation.