Interaction to Next Paint (INP)

The page responds to user interactions in under 0.2 seconds.

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    About

    Interaction to Next Paint (INP) measures how quickly a webpage responds to user actions like clicks or typing. It tracks the time from when you interact until the next screen update. A good INP score is 200 milliseconds or less, ensuring a smooth experience. INP has replaced First Input Delay (FID) as a key performance metric.

    Risks

    Site feels frozen when users click things.

    Why it's important

    A fast response time increases interactivity and user satisfaction, leading to a more engaging experience.

    User stories

    As a user interacting with the page, I want the site to respond quickly to my actions so that I feel in control and don't experience delays.
    As a user of a cheaper model mobile phone, I want your website to respond to my interactions quickly. If it is inefficient and performs a lot of processing on my device I wonder if it is even working, get stressed out and may click multiple times.

    Code

    Failing pattern:

    // Fail: long-running synchronous work on the main thread
document.getElementById("btn").addEventListener("click", () => {
  heavyComputation(); // blocks the main thread
});

    Passing pattern:

    // Pass: defer heavy work off the main thread
document.getElementById("btn").addEventListener("click", () => {
  setTimeout(() => heavyComputation(), 0);
});

    Error

    ScanGov messaging when a site fails a standard:

    Page response exceeded 0.2 seconds.

    Guidance

    Indicators

    On this page

      Plans Demo