---
title: "What is Time to Interactive (TTI)? · Unlighthouse"
meta:
  "og:description": "TTI measured page interactivity but was deprecated in Lighthouse 10. Learn what replaced it."
  "og:title": "What is Time to Interactive (TTI)? · Unlighthouse"
  description: "TTI measured page interactivity but was deprecated in Lighthouse 10. Learn what replaced it."
---

**Glossary**

# **What is Time to Interactive (TTI)?**

[Copy for LLMs](https://unlighthouse.dev/glossary/tti.md)

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

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](#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 dramatically inflate TTI
- **Better alternatives exist** - [**TBT**](https://unlighthouse.dev/glossary/tbt) measures blocking more robustly
- **Poor correlation with real experience** - Terrible TTI could still feel responsive

## [What Replaced TTI](#what-replaced-tti)

### [Lab Testing](#lab-testing)

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

### [Field Measurement](#field-measurement)

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

## [Historical Thresholds](#historical-thresholds)

| **Score** | **Rating** |
| --- | --- |
| ≤ 3.8s | Good |
| 3.8s - 7.3s | Needs Improvement |
| > 7.3s | Poor |

## [Migration](#migration)

| **Old** | **New** |
| --- | --- |
| TTI in Lighthouse | Use [**TBT**](https://unlighthouse.dev/glossary/tbt) |
| TTI in field/RUM | Use [**INP**](https://unlighthouse.dev/glossary/inp) |
| TTI CI assertions | Switch to TBT thresholds |

[Edit this page](https://github.com/harlan-zw/unlighthouse/edit/main/docs/glossary/tti.md)

[Markdown For LLMs](https://unlighthouse.dev/glossary/tti.md)

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[**TTFB** TTFB measures server response time. Learn what it is, thresholds, and how to optimize it.](https://unlighthouse.dev/glossary/ttfb)

**On this page **

- [Why TTI Was Deprecated](#why-tti-was-deprecated)
- [What Replaced TTI](#what-replaced-tti)
- [Historical Thresholds](#historical-thresholds)
- [Migration](#migration)