Time to Interactive Helper
Estimate your page's Time to Interactive score and get actionable recommendations to reduce JavaScript blocking time.
Page Parameters
Total size of your own JS files (uncompressed). Check Network tab in DevTools.
Analytics, ads, chat widgets, tag managers, etc.
Percentage of JS that loads after the page is interactive (code-splitting, dynamic import, defer attribute).
Estimated Time to Interactive
—
seconds
Enter values and click Calculate
Adjust the parameters on the left to estimate your TTI.
Good <3.8 s
Needs work 3.8–7.3 s
Poor >7.3 s
Time Breakdown
No results yet.
Optimization Recommendations
- No results yet.
JavaScript Budget Reference
| Network | CPU | Max JS for Good TTI |
|---|---|---|
| Fast 3G | 4x mobile | ~130 KB |
| Slow 4G | 4x mobile | ~300 KB |
| Fast 4G | 4x mobile | ~700 KB |
| WiFi | 1x desktop | ~2,500 KB |
Summary
Estimate your page's Time to Interactive score and get actionable recommendations to reduce JavaScript blocking time.
How it works
- Enter your total JavaScript bundle size (KB) loaded on the page.
- Select the network connection type your target users are on.
- Choose a CPU speed multiplier to simulate slower mobile devices.
- Optionally enter any third-party script sizes (analytics, ads, etc.).
- Click Calculate to see estimated TTI, a breakdown of blocking phases, and a rating against Core Web Vitals thresholds.
- Review the recommendations panel to find the highest-impact optimizations.
Use cases
- Estimate TTI before deploying a new JavaScript feature.
- Compare TTI impact of different JS bundle strategies (code-split vs monolith).
- Simulate how your page performs on low-end Android devices.
- Understand how third-party scripts inflate TTI.
- Educate your team on the relationship between JS size and interactivity.
- Set a JS budget to keep TTI under the 3.8-second "Good" threshold.
- Diagnose why Lighthouse flags your page as having a high TTI.
- Prioritize which scripts to defer, lazy-load, or remove entirely.
Frequently Asked Questions
Last updated: 2026-06-10 ·
Reviewed by Nham Vu