---
title: "Bootstrap Passes Core Web Vitals on 45.7% of Mobile Sites. Tailwind Manages 36.8% - PageSpeed Matters"
description: "We matched Chrome field data to the CSS framework on 3 million sites. Bootstrap sites pass Core Web Vitals more often than Tailwind sites on mobile (45.7% vs 36.8%), but the difference is not the CSS. It is the JavaScript stack each framework travels with."
lang: en
json-ld:
---

[Bootstrap Passes Core Web Vitals on 45.7% of Mobile Sites. Tailwind Manages 36.8%](https://www.pagespeedmatters.com/resources/data-studies/css-frameworks-core-web-vitals)

We matched Chrome field data to the CSS framework on 3 million sites. Bootstrap sites pass Core Web Vitals more often than Tailwind sites on mobile (45.7% vs 36.8%), but the difference is not the CSS. It is the JavaScript stack each framework travels with.

Core Web Vitals pass rate, Bootstrap vs Tailwind (mobile)

Bootstrap

45.7% 

Tailwind CSS

36.8% 

Source: PageSpeed Matters analysis of 3 million origins with CrUX field data, May 2026.

The framework everyone calls heavier passes 8.9 points more often on phones.

Good responsiveness (INP), Bootstrap vs Tailwind (mobile)

Bootstrap

89.2% 

Tailwind CSS

73.7% 

Source: PageSpeed Matters analysis, mobile 75th-percentile field data, May 2026.

Tailwind is the styling default of the modern JavaScript ecosystem, and it carries that stack's main-thread cost.

Source: [Bootstrap Passes Core Web Vitals on 45.7% of Mobile Sites. Tailwind Manages 36.8% - PageSpeed Matters](https://www.pagespeedmatters.com/resources/data-studies/css-frameworks-core-web-vitals)