Performance Budget Calculator

Set realistic performance budgets for your web projects. Predict load times across devices and connection speeds. Export Lighthouse CI configs to enforce budgets in your build process.

⚡Real-time Predictions
📱Multi-Device Testing
📊Export Configs
🎯Industry Benchmarks

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Why Performance Budgets Matter

Performance budgets aren't just technical constraints—they're business imperatives that directly impact user experience, conversions, and revenue

User Experience Impact

53% of mobile users abandon sites that take longer than 3 seconds to load. Performance directly affects user satisfaction and engagement.

Conversion & Revenue

Every 100ms of load time improvement can increase conversion rates by 1%. Amazon found that 100ms delay costs them 1% in sales.

SEO Rankings

Google uses Core Web Vitals as ranking factors. Faster sites rank higher and get more organic traffic.

Mobile Performance

Over 60% of web traffic is mobile. Users on slower devices and networks need optimized experiences.

How Performance Budgets Work

A systematic approach to maintaining fast, user-friendly experiences

1

Define Your Budget

Set size limits for each resource type (HTML, CSS, JS, images, fonts) based on your target load time and audience.

2

Test & Measure

Use tools like Lighthouse, PageSpeed Insights, and WebPageTest to measure your current performance against your budget.

3

Enforce in CI/CD

Integrate Lighthouse CI into your build process to automatically fail builds that exceed your performance budget.

4

Monitor & Iterate

Continuously monitor real user metrics (RUM) and adjust your budget as your application evolves.

Understanding Core Web Vitals

Google's user-centric metrics for measuring real-world performance

MetricDescriptionTarget Values
Largest Contentful Paint (LCP)Measures loading performance. Should occur within 2.5 seconds of page load.< 2.5s2.5s - 4s> 4s
First Input Delay (FID)Measures interactivity. Should be less than 100 milliseconds.< 100ms100ms - 300ms> 300ms
Cumulative Layout Shift (CLS)Measures visual stability. Should maintain a score of less than 0.1.< 0.10.1 - 0.25> 0.25
Time to Interactive (TTI)When the page becomes fully interactive. Target under 3.8 seconds on mobile.< 3.8s3.8s - 7.3s> 7.3s
First Contentful Paint (FCP)When the first content appears on screen. Should be under 1.8 seconds.< 1.8s1.8s - 3s> 3s

Quick Wins to Reduce File Sizes

Proven strategies to significantly improve performance without sacrificing features

🖼️

Optimize Images

Convert images to modern formats like WebP and AVIF. Can reduce file sizes by 30-70% while maintaining quality.

  • Use our Image Converter tool to convert PNG/JPG to WebP/AVIF
  • Compress images before uploading
  • Use responsive images with srcset
  • Lazy load images below the fold
  • Consider using CDN image optimization services
Try Our Image Converter
📦

Code Splitting

Split JavaScript bundles so users only download code they need. Modern frameworks support this out of the box.

  • Use dynamic imports for route-based splitting
  • Lazy load heavy components and libraries
  • Split vendor code from application code
  • Use React.lazy() or Next.js dynamic imports
  • Analyze bundle sizes with webpack-bundle-analyzer
🗜️

Enable Compression

Gzip and Brotli compression can reduce text-based assets by 60-80%.

  • Enable Brotli compression on your server (better than Gzip)
  • Pre-compress static assets at build time
  • Ensure Content-Encoding headers are set correctly
  • Most CDNs handle compression automatically
🔤

Optimize Fonts

Web fonts can be heavy. Optimize loading strategy and use variable fonts when possible.

  • Use font-display: swap for faster perceived load
  • Subset fonts to only include needed characters
  • Use variable fonts instead of multiple weights
  • Preload critical fonts
  • Consider system font stacks for faster loads
🎯

Remove Unused Code

Tree shaking and dead code elimination can significantly reduce bundle sizes.

  • Use modern build tools that support tree shaking
  • Audit dependencies with webpack-bundle-analyzer
  • Remove unused CSS with PurgeCSS or similar
  • Use imports from specific paths (e.g., lodash/debounce vs lodash)
  • Regularly review and remove unused dependencies
⚡

Lazy Loading

Defer loading of non-critical resources until they are needed.

  • Lazy load images with loading="lazy" attribute
  • Defer non-critical JavaScript
  • Use Intersection Observer for dynamic loading
  • Lazy load third-party embeds (videos, maps, social widgets)
  • Consider lazy loading below-the-fold content
🔗

Resource Hints

Help browsers prioritize and preload critical resources.

  • Use <link rel="preload"> for critical resources
  • Use <link rel="prefetch"> for next-page resources
  • Use <link rel="preconnect"> for third-party domains
  • Use <link rel="dns-prefetch"> for DNS resolution
  • Prioritize above-the-fold content
📡

Use a CDN

Content Delivery Networks serve assets from locations close to users, reducing latency.

  • Serve static assets from a CDN
  • Use edge caching for dynamic content
  • Enable HTTP/2 or HTTP/3 for multiplexing
  • Configure proper cache headers
  • Consider edge computing for API responses

Measuring Your Current Performance

Essential tools for auditing and monitoring web performance

Google PageSpeed Insights

Free tool that analyzes your page and provides both lab and field data with specific recommendations.

Best for quick audits and getting actionable recommendations

Visit Tool →

Lighthouse

Open-source automated tool built into Chrome DevTools. Provides comprehensive performance audits.

Best for development and detailed technical analysis

Visit Tool →

WebPageTest

Advanced testing tool that lets you test from multiple locations, devices, and connection speeds.

Best for detailed waterfall analysis and testing specific scenarios

Visit Tool →

Chrome DevTools Network Tab

Built-in browser tool for analyzing all network requests, timing, and resource sizes.

Best for real-time debugging during development

Visit Tool →

Lighthouse CI

Continuous integration tool that fails builds when performance budgets are exceeded.

Best for enforcing performance budgets in CI/CD

Visit Tool →

Setting Realistic Budgets

Strategic approaches to defining performance targets that balance user experience and feature requirements

Start with Target Load Time

Begin with a target load time (e.g., Time to Interactive under 3s on 3G) and work backwards to determine file size budgets.

Analyze Competitors

Use PageSpeed Insights to analyze competitor sites in your industry. Aim to be faster than the average.

Consider Your Audience

If your users are primarily on mobile or in regions with slower networks, be more aggressive with budgets.

Progressive Enhancement

Ensure core functionality works within your budget, then progressively enhance for better connections.

Allocate Strategically

JavaScript is most expensive (parsing + execution). Images are cheaper but add up. Balance based on your needs.

Industry Benchmarks

Typical performance budgets across different sectors

IndustryJavaScriptImagesTotalNotes
News & Media150-300 KB400-800 KB800-1500 KBContent-heavy, image-rich sites
E-commerce200-400 KB300-600 KB800-1500 KBProduct images, interactive features
Landing Pages100-200 KB200-400 KB400-800 KBConversion-focused, minimal complexity
SaaS/Dashboards300-600 KB100-300 KB600-1200 KBFeature-rich applications
Blogs100-250 KB300-500 KB600-1000 KBContent-focused with images
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Need Help Optimizing Your Website?

Our team of performance experts can audit your site, identify bottlenecks, and implement optimizations that dramatically improve load times and Core Web Vitals. We've helped businesses achieve 50%+ performance improvements.

Schedule Free Performance Audit