### Package List

Enter package names (one per line)_react react-dom axios_

Consider lazy loading

Analyze Bundle

### Analysis Results

Enter packages and click Analyze

# Bundle Size Estimator

Compare fixed JavaScript package size references; verify actual bundle and transfer sizes in your production build.

## Key Features

#### Size Analysis

Minified and gzipped size estimates

#### Load Time

Estimated download time

#### Lazy Loading

Identify lazy-loadable packages

#### Comparison

Compare multiple packages

#### Export Reports

Download analysis results

#### Optimization

Get improvement suggestions

## Understanding Bundle Sizes

JavaScript bundle size can affect download and execution time. This estimator adds fixed reference values for a limited set of named packages; it does not inspect your project, installed versions or production build. Unknown names are skipped, and duplicate names are counted more than once. Use the results for a rough comparison, not as measured transfer size or a ranking guarantee.

### Size Metrics Explained

#### Minified Size

Code with unnecessary characters removed. The size reduction depends on the original code and build.

#### Gzipped Size

A compressed representation of code. Actual transfer size varies with content and server settings.

#### Load Time

A simplified transfer estimate assuming a 10 Mbps connection; it excludes latency and execution time.

#### Lazy Load Savings

Potential size reduction by lazy loading non-critical code.

### How to Use Bundle Size Estimator

1. Enter one supported package name per line in the Package List.
2. Choose whether to include the hypothetical lazy-loading estimate.
3. Select Analyze Bundle and review the recognized packages and reference totals.
4. Measure your actual application build separately; the reference values do not reflect its imports, versions or bundler.

For example, entering react and axios compares the built-in reference figures, not your installed versions. Your actual bundle can differ because of import choices, shared dependencies and build settings. Use the [CSS Minifier](https://www.toolcomb.com/css-minifier) for a stylesheet, or review your production build and transfer size in browser developer tools.

### Frequently Asked Questions

#### What is bundle size?

Bundle size is the total size of your JavaScript code after minification and compression.

#### What's the difference between minified and gzipped?

Minified removes unnecessary characters. Gzipped compresses the minified code further for transfer.

#### How does lazy loading help?

Lazy loading defers loading non-critical code until needed, reducing initial bundle size.

#### What's a good bundle size?

There is no universal ideal size. Set a budget for your users and measure the production build on representative devices and networks.

## Related Tools

Discover more free tools that might help with your next task.

[Color Studio Explore palettes, tints, and shades for your UI Use Tool](https://www.toolcomb.com/color-studio)

[CSS Animations Build and preview CSS animations Use Tool](https://www.toolcomb.com/css-animations)

[Screen Reader Preview Preview how screen readers interpret your HTML Use Tool](https://www.toolcomb.com/screen-reader-preview)

[CSS Pattern Generate CSS background patterns Use Tool](https://www.toolcomb.com/css-pattern)

[CSS Minifier Beautify or minify CSS in your browser Use Tool](https://www.toolcomb.com/css-minifier)

### Related guides

Read the how-to, then come back to this tool when you are ready to run it locally.

- [A Pre-Launch Checklist for a New Web Page Title tags, meta description, Open Graph, SERP snippet, favicon, bundle weight, lazy-load, and a first accessibility pass - before you ship, without a login.](https://www.toolcomb.com/blog/pre-launch-checklist-for-a-new-web-page)
- [How to Convert Bytes, Bits, KB, MB, and GB SI vs binary prefixes for storage. Convert locally while debugging downloads.](https://www.toolcomb.com/blog/how-to-convert-bytes-bits-kb-mb-gb)
- [Best CSS and Frontend Design Tools Color palettes, CSS animation previews, favicons, patterns, bundle size, and screen-reader checks - all in the browser.](https://www.toolcomb.com/blog/best-css-and-frontend-design-tools)

[View All Tools](https://www.toolcomb.com/tools)