JavaScript Dependency Weight Estimator
Select the JavaScript libraries you plan to use: the tool adds up their known approximate sizes (minified and gzipped) to give you a rough idea of the weight added to your bundle, before installing anything.
How it works
A local database (embedded in the page, no network calls) associates each common library with two approximate sizes: the minified size and the gzipped size (what the browser actually downloads in production on a properly configured server). Check the libraries you're considering: the sizes add up automatically to give an order of magnitude for the total weight added to your JavaScript bundle.
Are these sizes exact?
No, these are rough estimates: the real size depends on the exact installed version, the bundler used (Vite, Webpack, esbuild...), and especially tree-shaking (importing only the functions you use can drastically reduce the real weight, particularly for libraries like Lodash). For an accurate, up-to-date figure for the exact version you're using, check a tool like bundlephobia.com.
Why add gzipped sizes rather than just minified ones?
The minified size is the weight of the JavaScript file after removing spaces and shortening variable names, but the gzipped size best reflects what the user actually downloads, since gzip or brotli compression is almost standard on modern web servers.
No data is sent to a server: the size database is embedded in the page and the calculation happens entirely in your browser.