---
title: "First Input Delay (Help Center / Glossary / Metrics)"
canonical: "https://www.rumvision.com/help-center/glossary/metrics/first-input-delay/"
---

Breadcrumbs: [Home](https://www.rumvision.com/?format=md) > [Help Center](https://www.rumvision.com/help-center/?format=md) > [Glossary](https://www.rumvision.com/help-center/glossary/?format=md) > [Metrics](https://www.rumvision.com/help-center/glossary/metrics/?format=md) > First Input Delay

# First Input Delay

The First Input Delay metric aims to measure the delay during the first input.

> This metric is available in [RUM](https://www.rumvision.com/help-center/glossary/monitoring/real-user-monitoring/?format=md) & [synthetic monitoring](https://www.rumvision.com/help-center/glossary/monitoring/synthetic-monitoring/?format=md), but not in [soft navigations](https://www.rumvision.com/help-center/glossary/browser/soft-navigations/?format=md).  
>  FID will no longer be part of Core Web Vitals after March 12.

## Nuances of the First Input Delay metric

There are some important nuances when it comes to the First Input Delay metric:

- **Single Page Applications**  
     If your site is a Single Page Application, there are [exceptions when it comes to tracking Core Web Vitals](https://www.rumvision.com/help-center/glossary/other/single-page-application/?format=md#core-web-vitals) across all page navigations.
- **only the first interaction**  
     The metric perfectly described what is does: it only collects data related to the first interaction, while a typical webpage has way more interactions.
- **only the input delay**  
     And it's only collecting the input delay, while there are many more tasks involved with user interaction that could (cumulatively) build up to a long delay after a user interaction.
 
The above are reasons why Google was working on and introduced the [INP metric](https://www.rumvision.com/help-center/glossary/metrics/interaction-to-next-paint/?format=md).

### Replaced by INP

On January 31st, Google announced that on, [March 12 INP will become part of Core Web Vitals](https://www.rumvision.com/blog/march-12-is-when-google-inp-becomes-core-web-vital/?format=md). It is replacing the FID metric, meaning that FID will then no longer be a Core Web Vitals metric.

Moreover, the Google docs are stating that it will be removed from other tools.

## Continue reading about First Input Delay

Want to learn more about First Input Delay? [Check our blog](https://www.rumvision.com/blog/?tag=fid&format=md), check the [web.dev FID](https://web.dev/articles/fid) article or keep an eye out on the [changes to the FID metric](https://chromium.googlesource.com/chromium/src/+/master/docs/speed/metrics_changelog/fid.md).