Check the bundle size of any npm package — minified, gzipped, and tree-shaken. Powered by the Bundlephobia public API.
This tool fetches the minified and gzipped bundle size for any npm package — the same numbers you'd see on Bundlephobia — without leaving your browser. Enter a package name and optional version to instantly see how much it would add to your JavaScript bundle, along with the download size and a list of its dependencies with their individual sizes.
Keeping bundle size under control directly affects page load performance and Core Web Vitals scores. Checking a package's weight before adding it to a project takes seconds and can prevent costly refactors later — especially for utility libraries, date formatters, and validation libraries that often have lighter alternatives.
lodash or react@18.2.0)Minified size is the file after whitespace, comments, and long variable names are removed — but it is still plain text. Gzipped size is the minified file compressed with gzip, which is what browsers actually download when a server sends the Content-Encoding: gzip header. Gzipped size is typically 60–80% smaller than minified size and is the most relevant number for network performance.
Yes — append the version after an @ symbol, e.g. axios@0.27.2 or lodash@4.17.21. Without a version, the tool fetches the latest published version. This is useful for comparing bundle impact between a version you already have and a newer release.
No — peer dependencies (like React or Vue for component libraries) are excluded from the size calculation because they are assumed to already be present in your project. The reported size covers only the package itself and its non-peer dependencies, so the actual bundle impact may be higher if peer deps are not yet installed.