---
title: How to set up analytics
description: Measure and track page performance using Next.js
url: "https://nextjs.org/docs/pages/guides/analytics"
version: 16.2.2
lastUpdated: 2026-04-02
router: Pages Router
prerequisites:
  - "Guides: /docs/pages/guides"
---


Next.js has built-in support for measuring and reporting performance metrics. You can either use the [`useReportWebVitals`](/docs/app/api-reference/functions/use-report-web-vitals) 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.

## Client Instrumentation

For more advanced analytics and monitoring needs, Next.js provides a `instrumentation-client.js|ts` file that runs before your application's frontend code starts executing. This is ideal for setting up global analytics, error tracking, or performance monitoring tools.

To use it, create an `instrumentation-client.js` or `instrumentation-client.ts` file in your application's root directory:

```js filename="instrumentation-client.js"
// Initialize analytics before the app starts
console.log('Analytics initialized')

// Set up global error tracking
window.addEventListener('error', (event) => {
  // Send to your error tracking service
  reportError(event.error)
})
```

## Build Your Own

```jsx filename="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 filename="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
>   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).
---

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