Interaction to Next Paint (INP)

What the stopwatch is actually timing

Someone taps a button on your site. Something has to change on the screen: a menu slides open, a field takes the first character, a button dims to show it was pressed. INP is the gap between the tap and the moment the screen actually changes.

That gap exists because a browser does most of its work in one lane. Scripts run there: the chat bubble, the tracking tags, the image slider, the popup waiting for someone to leave. If something in that lane is busy when a finger lands, the tap waits its turn.

The word visible is doing real work in the name. The page does not have to finish the job inside that window. It has to show that it heard you. A button that dims, a spinner, a field that draws the character it just received, all of those count. A form that goes quiet and thinks while the screen sits unchanged does not.

It is measured across the whole visit, not just the first tap, and it leans toward the worst responses instead of the average. That matches how people remember a site. Nobody recalls the nine taps that worked. They recall the one where they pressed Send twice because nothing happened.

It is also measured on real visits rather than on a test bench, so it reflects the phones and the cell connections your customers carry, not the desktop sitting on your desk.

What a sticky tap costs when the phone is the front door

Local service sites get used at bad moments. A wet floor, a driveway at dusk, a parking lot with one bar of signal. The tap that matters is almost always Call, Get a quote, or Send.

When a button takes a beat to acknowledge, people press it again. You get the same lead twice with no way to tell which one is real, or you get a half-filled form and a caller who moved on to the next name on the list. Neither one shows up in a report as a speed problem. They show up as a quiet week.

Responsiveness is a build decision more than a settings decision, which is why it sits with our web development work rather than with a plugin you switch on.

It matters most where the phone is the working tool. One build of ours is a job board for a Philadelphia staffing agency, where the owner posts openings from her phone. Every control on it has to answer the first time she presses it.

Where it sits among the other Core Web Vitals

The Core Web Vitals cover different complaints. Largest Contentful Paint asks how long until the main thing on the page appears. Cumulative Layout Shift asks whether the page moves under your thumb while you are reading it. INP asks what happens after you touch it.

A page can do well on one and badly on another, which is why a single grade out of a hundred hides more than it tells. Poor scores here usually trace back to the same place: too much script trying to run at once, and features bolted on over the years that nobody ever took back off.