Image compression tool
Shrink JPG, PNG and WebP images and see the exact size you saved. Add a whole batch, set a quality level, resize, convert the format, then download one at a time or as a ZIP. Your images are decoded and re-encoded by your own browser, so nothing is uploaded and nothing is stored.
What does this image compressor do?
It compresses JPG, PNG and WebP images in your browser and reports the real file size before and after. Nothing is uploaded: each image is decoded and re-encoded on your own device using a canvas, so no file is ever sent to a server. Set a quality level between 10% and 100%, resize by width or height with the aspect ratio preserved, choose an output format, then download the images one at a time or all together.
Your images never leave this device. They are decoded and re-encoded by your own browser using a canvas. No image is uploaded, no image is sent to a third party, and nothing is stored on a server. Closing the tab discards everything.
Empty state. No images yetAdd one above and it will be compressed automatically.
Quality applies to JPEG and WebP output. Keep the original format unless you have a reason to change it.
JPEG and WebP take a quality setting. PNG is lossless, so the quality slider does nothing to it โ a PNG gets smaller by being resized or converted to WebP. Converting a transparent image to JPEG flattens the transparency onto white.
Percentage of the original size. Leave empty for no change.
Percentage first, then width or height. With the lock on, the other dimension is worked out for you. Images are never enlarged.
How to compress an image
Add your images
Drop one or more images onto the area above, or use the file picker to choose them. JPG, PNG and WebP are accepted, up to 20 images at a time and 25 MB each.
Pick a quality level or a preset
Drag the quality slider between 10% and 100%, or use Low size, Balanced or High quality to set a sensible starting point. This setting controls JPEG and WebP output.
Resize or change the format
Enter a percentage, or a maximum width and height, to scale the image while keeping its aspect ratio. Choose an output format to convert between JPG, PNG and WebP.
Download the results
Download each compressed image on its own, or download the whole batch as one ZIP. Every image is processed on your own device and is never uploaded.
How the compression works
Your browser can already decode an image and encode it again, so the tool does exactly that and nothing else. Each file is read into an image bitmap, drawn onto a canvas at the size and quality you chose, and encoded back out as a JPG, PNG or WebP by the image encoder built into your browser. No image is sent to a server, because there is no server involved.
That is also why the reported numbers are trustworthy. The percentage is calculated from the bytes the browser actually produced against the bytes of the file you added, not estimated from the quality slider. And when compression makes a file larger โ which happens, most often with an already-optimised PNG โ the tool says so plainly and offers you the original back instead of reporting a saving that did not happen.
Which format should you choose?
| Format | How it compresses | Transparency | Use it for |
|---|---|---|---|
| JPEG | Lossy, with an adjustable quality from 10% to 100%. | Not supported. Transparency is flattened onto white. | Photographs and anything with lots of continuous tone. |
| PNG | Lossless. The quality slider has no effect on it. | Supported, including partial transparency. | Logos, icons, screenshots and anything with sharp edges or text. |
| WebP | Lossy with an adjustable quality, and usually smaller than JPEG. | Supported. | The web in general, when you control where the image is served. |
WebP is normally the best default for the web: at the same perceived quality it is often 25 to 35 per cent smaller than JPEG. The catch is support โ it is universal in current browsers, but an old app or an email client may not render it, and a logo with transparency should stay PNG unless you know every destination supports WebP.
How much can an image actually be compressed?
It depends on the source. A photograph that has already been through a compressor usually saves 30 to 70 per cent at 80% quality. A PNG screenshot is already lossless, so it saves almost nothing unless you resize it or convert it. The honest summary is that a large saving means a visible quality cost, which is why this tool shows you the real before and after size for every file instead of a number it cannot substantiate.
Resizing versus re-encoding
If an image is far larger than it needs to be, resizing does more than any quality setting. Halving both dimensions removes three quarters of the pixels before the encoder sees them, and the result usually looks identical at the size it will be displayed. This tool never enlarges an image, because inventing pixels that carry no detail makes the file bigger without adding information.
The rest of this site works on text rather than images. Count and convert words on the text tools page, turn styled text into a 1200 by 630 PNG in the font studio, or change how text looks with the fancy text generator. If you want to see a lot of styles side by side before picking one, the style guides put 25 words in 25 styles on one page, and the font index lists every style by category.
Common questions
Are my images uploaded anywhere?
No. Every image is decoded and re-encoded by your own browser, on your own device, using a canvas element. The page makes no request containing your image, there is no storage, and closing the tab discards everything. This is the same position the rest of this site takes with typed text.
How much can an image actually be compressed?
It depends entirely on the source. A photograph that has already been through a compressor usually saves 30 to 70 per cent at 80% quality. A PNG screenshot is already lossless, so it saves almost nothing unless you resize it or convert it to WebP. The honest answer is that a large saving means a visible quality cost, and the percentage this tool reports is measured from the real bytes it produces rather than estimated.
What quality setting should I use?
80% is the default and the right choice for images on the web: the file gets noticeably smaller and most people cannot tell the difference at normal viewing size. Use 90% or above when the image will be printed or edited again, 60 to 70% for thumbnails, and expect visible banding and artefacts below 50%, especially across skies and smooth gradients.
Does resizing change my image aspect ratio?
Not unless you ask it to. While the aspect-ratio lock is on, typing a width computes the height for you and typing a height computes the width. Turn the lock off and fill in both fields to stretch the image deliberately, which is almost never what you want for a photo.
Which output format should I choose?
Keep the original format unless you have a reason to change it. WebP is usually 25 to 35 per cent smaller than JPEG at the same perceived quality and is the better default for the web, because it also keeps transparency. PNG is the safe choice when you need lossless pixels or sharp edges, such as a screenshot or a logo that will be scaled up. JPEG cannot hold transparency at all, so choosing it for an image that has any flattens that transparency onto a solid white background, and the tool warns you when it detects that it is about to.
Why did my PNG get bigger instead of smaller?
PNG is lossless, so the quality slider has nothing to work on and re-encoding a flat-colour image often adds a little overhead rather than removing any. To actually shrink a PNG, resize it to the dimensions you need, or convert it to WebP or JPEG, both of which are designed to discard detail the eye cannot see at that size.
Is there a limit on how many images I can compress?
Up to 20 images per batch and 25 MB per image, with a ceiling of 16,000 pixels on a side and 40 megapixels in total. Those limits exist so that decoding a very large file cannot exhaust the memory of a phone, not to restrict normal use: they are far above what a web page normally serves. Nothing is queued or stored, so there is no cap on how much you compress over the course of a visit.