How to compress an image
Choose a PNG, JPG, or WebP image, select JPEG or WebP output, then either set quality manually or ask the tool to search for a result near a target decimal-KB size. The selected file and generated result stay in the current browser tab.
Decide what to change first
Compression quality is only one way to reduce an image. If a 2400 × 1600 photo will only be displayed around 1200 pixels wide, resizing first can remove far more data than repeatedly lowering encoder quality. Use the Resize Image tool when the source dimensions are materially larger than the destination, then return here if the resized file still needs to be smaller.
If dimensions are already appropriate, format and encoder quality become the main levers. JPEG is practical for photographs when transparency is not required. WebP can also compress photographic content and can preserve transparent pixels in browser-generated output. The image size, format, and quality guide explains how these choices interact.
Target-size mode
Target-size mode keeps the original dimensions and tests at most 12 encoder quality values between the supported quality bounds. It keeps the highest tested quality that actually satisfies the target. If none of the tested candidates reaches the target, the tool labels that clearly and shows the smallest result it actually measured. One decimal KB equals 1,000 bytes.
Choosing a quality setting
The quality control is an encoder input, not a promise that an image retains an exact percentage of visual detail. Two images at the same setting can have very different results because texture, noise, gradients, and sharp edges compress differently.
A practical workflow is to start near the default setting, generate the result, inspect it at the size people will actually see, and lower quality only while the visual change remains acceptable. Keep the source file if the image may need future editing.
When the result is larger
Compression is not guaranteed to make every file smaller. A source may already be heavily optimized, and changing formats can add different headers or encode certain graphics less efficiently. The workspace reports the actual source/result sizes so you can reject a larger output rather than assuming every conversion is an improvement.
Transparency and JPEG backgrounds
JPEG does not support alpha transparency. When a transparent PNG is converted to JPEG, transparent pixels need a background; this tool uses the documented background behavior in the workspace. Choose WebP instead when the destination supports it and transparent pixels must remain transparent.
Privacy and limits
Processing is local to the browser tab: MyTool0 does not upload the selected image for compression. Local processing describes the file-processing path, not ordinary page-loading requests; see what browser-local processing means for that distinction.
Large images can still use significant device memory when decoded. Inputs are limited to 20 MB, 8,192 pixels per side, and 16 megapixels; processing moves to a local worker when browser support allows it. Animated PNG/WebP inputs are rejected because this tool produces one still image and must not silently discard frames. Keep another copy of important originals before replacing them.