NPM Package Size Estimator
Type an npm package name; get its minified size, gzipped size, dependency count, and whether it supports tree-shaking. Data is fetched live from bundlephobia. Useful before adding a dependency, or for justifying replacing a heavy package with a lighter one.
How to use the NPM Package Size Estimator
Type a package name (with version optional: [email protected]). The tool queries bundlephobia's API and returns size data plus dependency info. If a package isn't in their cache, the first request takes a few seconds while they build it.
Estimating npm package size
Every dependency you add ships to the browser, and a package that looks small can pull in a tree of transitive dependencies that quietly inflates your bundle — the classic case being a date or utility library that adds far more weight than the one function you actually needed. Knowing the cost before installing saves a painful audit later.
This looks a package up on bundlephobia and reports its minified and gzipped size, dependency count, and whether it is tree-shakeable, so you can compare alternatives — a modular ES build against a monolithic one, say — before committing to one. Once the manifest is in place, the package.json validator checks it for common mistakes.
Common use cases
- Pre-install check — see a package’s weight before adding it.
- Compare alternatives — weigh date-fns against moment, or lodash-es against lodash.
- Justify a swap — quantify the saving from replacing a heavy dependency.
- Check tree-shaking — confirm a package supports it before relying on it.
- Audit a bundle — spot the dependency inflating your build.