Image Compressor

Shrink JPG, PNG and WebP images by quality or to an exact size in KB, without uploading them.

Drop images here or paste them, or

Your images never leave your device

Processed in this browser · JPG, PNG, WebP, GIF, BMP, AVIF or HEIC · up to 50 at a time

Compress by

Quality75

Lower is smaller; above 90, files grow quickly for little visible gain. PNG files keep 128 colours.

Output format

Shrink large images

Makes image files smaller, either at a quality you choose or to fit a size limit in KB, such as the 20 KB or 50 KB a job, exam or visa form asks for. Add up to 50 images at once and download them singly or together as a ZIP. Images are compressed in your browser and never uploaded.

How to use it

Quality (1–100, default 75) sets how much detail JPG and WebP keep: lower gives a smaller file with more visible blur and blockiness. For PNG it sets how many colours the image keeps, from 256 at 90 and above down to 16.

Target size takes a maximum from 1 to 10,000 KB (default 50) and an optional minimum, for forms that reject files that are too small. With Allow resizing to reach the target on (the default), the image is made smaller in pixels when lowering the quality is not enough. With it off, the dimensions stay and a file that cannot get under the maximum says how small it got.

Output format keeps each image's format, or saves all as JPG, WebP or PNG. JPG and WebP compress photos far more than PNG. GIF and BMP are saved as PNG and HEIC as JPG, since browsers cannot write them. An AVIF stays AVIF where this browser can save it, and otherwise becomes WebP, or JPG. A browser that cannot save WebP, such as Safari, saves a WebP as JPG. Shrink large images scales any image whose longest side is over the size you set (default 2,048 px) down to it; smaller images keep their size. Background colour, shown when an image with transparency is saved as JPG, fills its transparent areas, which JPG cannot hold.

When re-saving would make a file larger, or the original is already within the target, you get the original with its metadata removed instead, and the result says so.

Each result shows over its original: drag the divider to compare them, and zoom to 100% or 200% to see compression at its real size. Options are remembered on this device, and Reset options puts them back to the defaults.

How the target size is reached

Portals disagree on what a kilobyte is: some count 1,000 bytes, others 1,024. So a maximum is read as 1000 bytes per KB and a minimum as 1,024, and the file fits under either count. Sizes shown here use 1 KB = 1,000 bytes.

The image is saved at the highest quality whose file fits under the maximum, found by halving the range of qualities each try. With resizing allowed, the quality goes no lower than 50 for JPG and WebP, or 64 colours for PNG: below that, a smaller image looks better than a more compressed one. Instead the longer side shrinks to the largest size that fits, down to 16 px. Every file offered was measured after saving, so none is over the maximum.

A minimum is met only by keeping more quality. A file is never padded with filler bytes to reach it: if the best quality at full size is still too small, the result says so, and a larger or more detailed photo is the fix.

PNG is lossless, so its size comes down by reducing the image to a palette of at most 256 colours. The file stays a PNG and keeps its transparency. Photos compress far better as JPG or WebP.

Compressed images are saved afresh: camera details such as the date, model and location are removed, the orientation the camera recorded is applied to the pixels, and colours are converted to standard sRGB. A kept original loses the same camera details but keeps its colour profile and its orientation tag.

maximum in bytes = KB × 1,000

minimum in bytes = KB × 1,024

Examples

A form asking for 20 KB to 50 KB

With Target size, Max size 50 KB and Min size 20 KB, the file is kept between 20,480 bytes and 50,000 bytes. A portal counting 1,024 bytes per KB accepts up to 51,200 bytes, and one counting 1,000 accepts from 20,000 bytes: the file passes both.

A 100 KB limit

Max size 100 KB with no minimum keeps the file at or under 100,000 bytes, shown as 100 KB.

A PNG at the default quality

At Quality 75, a PNG keeps 128 colours. Logos, screenshots and diagrams usually look the same; photos may show banding in smooth gradients such as sky.

Frequently asked questions

No. Your browser reads, compresses and saves the images on your device; they are not sent to CornerTools or anyone else. To check, open the browser's developer tools at the Network tab and add an image: no request carries it. The first HEIC photo you add downloads a decoder from this site: a download to your browser, not an upload of your photo.

Check the limit is in KB, not MB, and that it applies to the file you upload rather than its dimensions in pixels: some forms set both. Files from this tool already fit limits that count 1,024 bytes per KB as well as 1,000.

A PNG reduced to a palette can show bands where colours blend smoothly; raise the Quality or save as JPG or WebP. Photos in a wide colour space (Display P3 from recent phones) or CMYK JPGs from print software are converted to sRGB, which can look slightly less vivid.

An image that was already well compressed can grow when saved again. The original is then kept, with its metadata removed. A HEIC photo has no original to keep, since it must be saved in another format, and HEIC stores photos more compactly than JPG or WebP: use Target size for a smaller file.