---
title: Analytics
description: Measure and track page performance using Next.js Speed Insights
url: "https://nextjs.org/docs/14/pages/building-your-application/optimizing/analytics"
docs_index: /docs/14/pages/llms.txt
lastUpdated: 2023-06-28
prerequisites:
  - "Building Your Application: /docs/14/pages/building-your-application"
  - "Optimizing: /docs/14/pages/building-your-application/optimizing"
---

> For an index of all documentation, see [/docs/14/pages/llms.txt](/docs/14/pages/llms.txt).

Next.js has built-in support for measuring and reporting performance metrics. You can either use the `useReportWebVitals` hook to manage reporting yourself, or alternatively, Vercel provides a [managed service](https://vercel.com/analytics?utm_source=next-site\&utm_medium=docs\&utm_campaign=next-website) to automatically collect and visualize metrics for you.

## Build Your Own

```jsx title="pages/_app.js"
import { useReportWebVitals } from 'next/web-vitals'

function MyApp({ Component, pageProps }) {
  useReportWebVitals((metric) => {
    console.log(metric)
  })

  return <Component {...pageProps} />
}
```

View the [API Reference](/docs/pages/api-reference/functions/use-report-web-vitals) for more information.

## Web Vitals

[Web Vitals](https://web.dev/vitals/) are a set of useful metrics that aim to capture the user
experience of a web page. The following web vitals are all included:

- [Time to First Byte](https://developer.mozilla.org/docs/Glossary/Time_to_first_byte) (TTFB)
- [First Contentful Paint](https://developer.mozilla.org/docs/Glossary/First_contentful_paint) (FCP)
- [Largest Contentful Paint](https://web.dev/lcp/) (LCP)
- [First Input Delay](https://web.dev/fid/) (FID)
- [Cumulative Layout Shift](https://web.dev/cls/) (CLS)
- [Interaction to Next Paint](https://web.dev/inp/) (INP)

You can handle all the results of these metrics using the `name` property.

```jsx title="pages/_app.js"
import { useReportWebVitals } from 'next/web-vitals'

function MyApp({ Component, pageProps }) {
  useReportWebVitals((metric) => {
    switch (metric.name) {
      case 'FCP': {
        // handle FCP results
      }
      case 'LCP': {
        // handle LCP results
      }
      // ...
    }
  })

  return <Component {...pageProps} />
}
```

## Custom Metrics

In addition to the core metrics listed above, there are some additional custom metrics that
measure the time it takes for the page to hydrate and render:

- `Next.js-hydration`: Length of time it takes for the page to start and finish hydrating (in ms)
- `Next.js-route-change-to-render`: Length of time it takes for a page to start rendering after a
  route change (in ms)
- `Next.js-render`: Length of time it takes for a page to finish render after a route change (in ms)

You can handle all the results of these metrics separately:

```js
export function reportWebVitals(metric) {
  switch (metric.name) {
    case 'Next.js-hydration':
      // handle hydration results
      break
    case 'Next.js-route-change-to-render':
      // handle route-change to render results
      break
    case 'Next.js-render':
      // handle render results
      break
    default:
      break
  }
}
```

These metrics work in all browsers that support the [User Timing API](https://caniuse.com/#feat=user-timing).

## Sending results to external systems

You can send results to any endpoint to measure and track
real user performance on your site. For example:

```js
useReportWebVitals((metric) => {
  const body = JSON.stringify(metric)
  const url = 'https://example.com/analytics'

  // Use `navigator.sendBeacon()` if available, falling back to `fetch()`.
  if (navigator.sendBeacon) {
    navigator.sendBeacon(url, body)
  } else {
    fetch(url, { body, method: 'POST', keepalive: true })
  }
})
```

> **Good to know:**
>
> If you use [Google Analytics](https://analytics.google.com/analytics/web/), using the
> `id` value can allow you to construct metric distributions manually (to calculate percentiles,
> etc.)

> ```js
> useReportWebVitals(metric => {
>   // Use `window.gtag` if you initialized Google Analytics as this example:
>   // https://github.com/vercel/next.js/blob/canary/examples/with-google-analytics/pages/_app.js
>   window.gtag('event', metric.name, {
>     value: Math.round(metric.name === 'CLS' ? metric.value * 1000 : metric.value), // values must be integers
>     event_label: metric.id, // id unique to current page load
>     non_interaction: true, // avoids affecting bounce rate.
>   });
> }
> ```
>
> Read more about [sending results to Google Analytics](https://github.com/GoogleChrome/web-vitals#send-the-results-to-google-analytics).

---

For a semantic overview of all documentation, see [/sitemap.md](/sitemap.md)

For an index of all available documentation, see [/docs/14/pages/llms.txt](/docs/14/pages/llms.txt)