First Input Delay (FID)

Name: First Input Delay

Referred To as FID

Category: Technical SEO , UX


First Input Display (FID) measures the initial processable interaction of a website user and the page. The exchange can be a tap on a button, click on a link, input event, or JavaScript-powered control.

First Input Delay, FID
First Input Delay (FID)

Your browser must process the event listeners and event handlers to reach your users. A browser may process the event listeners and handlers but fail to respond to the user. It so happens if the browser’s main thread is in a gridlock.

Correct Use: In simpler terms, FID measures the responsiveness and interactivities of a web page. A web page may load faster than its rivals. But, it may fail to permit the users to interact. Search Engines and web users perceive this as a poor performance. 

First Input Delay is a real-user Timing Metric that measures delay in milliseconds.

FID is one of Google’s Core Web Vital metrics, and Google uses FID as a ranking element for Google searches.

Our take: In general, FID measures the speed of a page. If a page loads faster, the sooner it becomes easy to interact.

A good FID is 100 milliseconds (ms) or less. Anything ranging from 100 MS to 300 MS is acceptable but needs improvement.

If your first input delay exceeds 300 MS, then your level of FID performance is poor. Therefore, your web page needs to get worked on properly.

If, say, about 75% of the website users and sessions experience an FID Load Timing below 100 MS, your website has a good performance.

Do: If you are using JavaScript, use these methods to reduce the time that JavaScript blocks the main thread;

  • Split up huge tasks into smaller and asynchronous ones: The main thread gets blocked when the commands are long, preventing user input processing. Splitting up the duties into smaller bits makes user input processing easier. To be safe, keep your tasks below 50 MS.
  • Create enough content statically: Strive to reduce the amount of data that requires post-processing on the client’s side. That decreases the work that the browser has to do to render a page.
  • Use web workers: To minimize the workload on the main thread, delegate some work to web workers. You have to entrust part of your JavaScript code to run on the worker thread. When you do so, the main thread does less work hence less input delay.
Tip: FID is essential in user experience, with a considerable impact on SEO Performance. Click To Tweet


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Poor FID scores and user experience creates suspicion for the Search Engine Algorithms. So, aim for good scores and create good user experiences.

Core Web Vitals – CWV

Core Web Vitals refers to an updated method of Google assessing the quality of web pages when deciding about ranking the search results pages.

CWV focuses on the actual user experience. The website will likely get a higher ranking when the user receives a good experience.

There are some particular factors assessed within Core Web Vitals. These are;

  • First Input Delay – FID: FID is the measure of a website’s responsiveness is.
  • Largest Contentful Paint (LCP): LCP is a metric designed to measure how fast a page loads to complete and loads an element on the screen.
  • Cumulative Layout Shift: CLS is the visual stability of a web page while loading.

You may have come across pages that, after you click, the content shifts. The shift is due to new elements appearing on your mobile device. You may sometimes click on an ad giving you an annoying experience, i.e., visual stability. CLS aims at assessing the visual stability of a page.