Interaction to Next Paint (INP) is a Core Web Vitals metric for how quickly a page responds. It measures the time from a user interaction until the browser paints the next frame, across all interactions during a visit.
At a glance
- Measures
- Latency of all clicks, taps and key presses during a visit, up to the next painted frame
- “Good” threshold
- 200 ms or less
- Assessment
- 75th percentile of page views
- Data source
- Field data preferred, also measurable in the lab
- Core Web Vital
- yes (responsiveness), since March 12, 2024
Last checked:
What does INP measure?
Clicks, taps and key presses count. Scrolling, hovering and zooming do not. The time covers input delay, the processing in event handlers and the rendering of the next frame. The reported value is usually the slowest interaction of a visit, with outliers ignored: one highest interaction is dropped for every 50. Google evaluates the 75th percentile of page views.
Assessed at the 75th percentile of page loads, mobile and desktop separately. Source: web.dev: Interaction to Next Paint (INP). Last checked: .
INP and FID
Since March 12, 2024, INP has replaced First Input Delay as a Core Web Vital. FID looked only at the delay before the first interaction. INP covers all interactions and includes the time until the visible result.
| Metric | Measures | Core Web Vital? | Field or lab | “Good” per web.dev |
|---|---|---|---|---|
| LCP (Largest Contentful Paint) | Render time of the largest image, text block or video visible in the viewport, from the start of navigation | yes (loading) | field and lab | 2.5 s or less |
| INP (Interaction to Next Paint) (this term) | Latency of interactions across the whole visit until the next paint; one value that all (or nearly all) interactions fall below | yes (interactivity), since 2024-03-12 | field; in the lab only with simulated interactions, Lighthouse does not measure INP | 200 ms or less |
| CLS (Cumulative Layout Shift) | Largest burst of unexpected layout shifts during the entire lifecycle of the page | yes (visual stability) | field and lab | 0.1 or less |
| TTFB (Time to First Byte) | Time from the start of navigation until the first byte of the response arrives | no (helps diagnose LCP) | field and lab | 0.8 s or less |
| FCP (First Contentful Paint) | Time from the start of navigation until any part of the page's content is rendered | no (helps diagnose LCP) | field and lab | 1.8 s or less |
| TBT (Total Blocking Time) | Total time after FCP during which the main thread was blocked long enough to prevent input responsiveness | no (lab proxy for INP) | lab; web.dev does not recommend field measurement | less than 200 ms on average mobile hardware |
| Speed Index | How quickly content is visually displayed during page load (from a video of the load) | no | lab (Lighthouse) | Threshold according to Lighthouse: mobile up to 3.4 s “fast” (web.dev gives no value) |
| FID (First Input Delay), historical | Time from the first interaction until the browser can begin processing event handlers | until 2024-03-12, replaced by INP | field only | 100 ms or less |
According to web.dev, the 75th percentile of page loads is assessed, mobile and desktop separately. A page passes the Core Web Vitals when LCP, INP and CLS are “good” at the 75th percentile. Chrome tools ended FID support on September 9, 2024. Sources: web.dev: Web Vitals; web.dev: Largest Contentful Paint (LCP); web.dev: Interaction to Next Paint (INP); web.dev: Cumulative Layout Shift (CLS); web.dev: Time to First Byte (TTFB); web.dev: First Contentful Paint (FCP); web.dev: Total Blocking Time (TBT); web.dev: First Input Delay (FID); web.dev Blog: Interaction to Next Paint is officially a Core Web Vital (2024-03-12); Chrome for Developers: Lighthouse – Speed Index. Last checked: .
- Google introduces Web Vitals. The first Core Web Vitals are LCP, FID and CLS.Source: blog.chromium.org
- Google announces a page experience ranking signal that combines Core Web Vitals with existing signals.Source: developers.google.com
- Google sets the date: the signals are to be used in ranking from May 2021.Source: developers.google.com
- Postponed: gradual rollout from mid-June 2021, full effect only by the end of August 2021.Source: developers.google.com
- Page experience update for mobile: Core Web Vitals become part of the ranking systems.Source: developers.google.com
- Page experience update for desktop, using the same Core Web Vitals thresholds as on mobile.Source: status.search.google.com
- INP is no longer experimental. Google announces that INP will replace FID as a Core Web Vital in March 2024.Source: web.dev
- INP replaces FID. Since then the Core Web Vitals are LCP, INP and CLS. Articles citing “FID 100 ms” as a threshold are out of date.Source: web.dev
- Chrome tools end support for FID.Source: web.dev
End of the mobile rollout: Google says “between June and August 2021”; the often-cited date of September 2, 2021 comes only from a Google Search Central post on X. Last checked: .
Typical causes of poor values
Long tasks on the main thread, heavy event handlers and large amounts of JavaScript, for example on pages with filters, menus or search.
Sources
- Interaction to Next Paint (INP) – web.devweb.dev
- INP becomes a Core Web Vital on March 12 – web.devweb.dev
- Interaction to next paint – MDNdeveloper.mozilla.org
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