---
title: "What is time to interactive (TTI)?"
description: "TTI measured page interactivity but was deprecated in Lighthouse 10. Learn what replaced it."
canonical_url: "https://unlighthouse.dev/glossary/tti"
last_updated: "2026-08-10T04:33:23.249Z"
---

<warning>

Time to Interactive (TTI) was **removed from Lighthouse 10** in February 2023. Use [TBT](/glossary/tbt) for lab measurement and [INP](/glossary/inp) for field measurement.

</warning>

Time to Interactive measured when a page became fully interactive - displaying useful content, event handlers registered, and responding within 50ms. It identified a 5-second "quiet window" with no Long Tasks.

## Why TTI was deprecated

[Google removed TTI](https://developer.chrome.com/blog/lighthouse-10-0) because:

- **Overly sensitive to outliers** - A single late network request could inflate TTI
- **Better alternatives exist** - [TBT](/glossary/tbt) measures blocking more robustly
- **Poor correlation with real experience** - Terrible TTI could still feel responsive

## What replaced TTI

### Lab testing

[Total Blocking Time (TBT)](/glossary/tbt) - Measures cumulative main thread blocking. Now has 30% Lighthouse weight.

### Field measurement

[Interaction to Next Paint (INP)](/glossary/inp) - Measures actual interaction responsiveness. Core Web Vital since March 2024.

## Historical thresholds

<table>
<thead>
  <tr>
    <th>
      Score
    </th>
    
    <th>
      Rating
    </th>
  </tr>
</thead>

<tbody>
  <tr>
    <td>
      ≤ 3.8s
    </td>
    
    <td>
      Good
    </td>
  </tr>
  
  <tr>
    <td>
      3.8s - 7.3s
    </td>
    
    <td>
      Needs Improvement
    </td>
  </tr>
  
  <tr>
    <td>
      > 7.3s
    </td>
    
    <td>
      Poor
    </td>
  </tr>
</tbody>
</table>

## Migration

<table>
<thead>
  <tr>
    <th>
      Old
    </th>
    
    <th>
      New
    </th>
  </tr>
</thead>

<tbody>
  <tr>
    <td>
      TTI in Lighthouse
    </td>
    
    <td>
      Use <a href="/glossary/tbt">
        TBT
      </a>
    </td>
  </tr>
  
  <tr>
    <td>
      TTI in field/RUM
    </td>
    
    <td>
      Use <a href="/glossary/inp">
        INP
      </a>
    </td>
  </tr>
  
  <tr>
    <td>
      TTI CI assertions
    </td>
    
    <td>
      Switch to TBT thresholds
    </td>
  </tr>
</tbody>
</table>