The Tool Desk
Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →To improve Interaction to Next Paint (INP), start with real-user field data, identify a slow interaction, inspect it in Chrome DevTools, address the work that delays its response, and verify the result in both a local recording and field monitoring. INP is a Core Web Vital that measures responsiveness across qualifying interactions during a page visit; it replaced First Input Delay (FID) as a stable Core Web Vital on March 12, 2024.
What INP measures—and why it matters
INP reflects how quickly a page responds to a user’s qualifying interactions, such as clicks, taps, and keyboard input, over the page visit. Rather than reporting only the first input, it considers interactions throughout the visit and reports a value intended to represent the experience of all or nearly all of them, with outlier handling in its implementation. A low INP means most interactions are answered quickly.
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The Chrome team’s official INP guide notes that 90% of a user’s time on a page is spent after it loads, based on Chrome usage data as reported in the guide’s 2025 update. That is why responsiveness after initial load matters: menus, filters, forms, and other controls still need to react promptly as people use the page.
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What counts as a good INP score?
Assess the 75th percentile of page loads, reported separately for mobile and desktop. The published thresholds are:
#1 Best Overall
| INP at the 75th percentile | Assessment |
|---|---|
| 200 ms or less | Good |
| Above 200 ms through 500 ms | Needs improvement |
| Above 500 ms | Poor |
A site-wide or combined-device number can conceal a problem affecting one device group. Check mobile and desktop separately, and treat the thresholds as field assessment criteria rather than a guarantee that every individual interaction will fall in the same band.
Where should you look for evidence?
Use field data to establish whether users are experiencing a problem. Then choose a specific interaction to investigate. Field data and lab recordings answer different questions: field data reflects real visits, while a local recording helps explain what happened during an interaction you reproduce.
| Source | What it helps establish | Important limitation |
|---|---|---|
| PageSpeed Insights and CrUX | Field status for eligible pages or origins, when CrUX data is available. | Aggregated data may show that INP is poor without identifying the interaction or page context responsible. CrUX eligibility and aggregation can also mean data is unavailable or differs from a site’s own RUM. |
| Search Console Core Web Vitals report | Field reporting for covered sites. | It is not an interaction-level trace that identifies a failing event handler. |
| Real user monitoring (RUM) | More detailed field context; interaction-level instrumentation can help connect a slow result to the relevant interaction. | What it reveals depends on the instrumentation and the context collected. |
| Chrome DevTools Performance panel | A local trace of an interaction you perform, useful for examining its timing and work. | A recording covers the flow and conditions exercised; it does not establish how all real users experience the page. |
For interaction-level field diagnosis, the attribution build of the web-vitals JavaScript library and insights from the Long Animation Frames API are options described in the official field guidance. Aggregate CrUX data alone should not be treated as proof that a particular handler is responsible.
How do you reproduce and inspect a slow interaction?
- Choose a real user flow. Use field evidence to pick a page and interaction that matter, such as opening a menu or applying a filter. Reproduce the actual sequence rather than testing an unrelated button.
- Start a recording. In Chrome DevTools, open the Performance panel and start a recording.
- Perform the interaction. Follow the selected flow, then stop the recording.
- Inspect the interaction. Expand the Interactions track and select a slow interaction. Examine its timing and the main-thread work around it to determine which part of the response is taking time.
- Retest after the change. Record the same flow under comparable conditions so the before-and-after traces are useful to compare.
A deliberately long synchronous block in an event listener can make processing duration visibly increase in a teaching demonstration. That illustrates one possible cause; it is not evidence that a production site has that problem. Lab results depend on the interactions and conditions exercised.
Rank #3
Which part of an interaction is slow?
INP’s interaction timing can be understood as three stages. The trace helps distinguish where time is being spent; the right fix depends on what it shows.
| Stage | What it measures | Diagnostic direction |
|---|---|---|
| Input delay | Time from the user’s input until the relevant event callbacks begin. | If callbacks start late, look for other work contending for the main thread. |
| Processing duration | Time taken by the relevant event callbacks to execute. | If callbacks themselves take too long, inspect their work and consider reducing or deferring it. |
| Presentation delay | Time until the browser produces the next frame containing the visual update. | If the visual response arrives late after callback work, inspect rendering and presentation work. |
What code changes can improve INP?
Base changes on the trace rather than applying optimizations by habit. The broad aim is to do less work in response to input and avoid work that blocks or delays the visual response.
If input delay is high
Look for other main-thread work that is running before the interaction callbacks can start. Break up long JavaScript tasks where appropriate so one task does not monopolize the main thread, and remove JavaScript that is unnecessary for the interaction or page.
If processing duration is high
Reduce the work performed by the event callbacks. Avoid doing more synchronously than is needed to respond to the input; defer nonessential work when the interaction does not need it immediately. Recheck the trace to confirm the relevant callback duration changed.
If presentation delay is high
Inspect the visual update triggered by the interaction. Avoid unnecessarily large rendering updates, and focus on the work that delays the next frame containing the response. A handler can finish without making the interaction feel fast if the browser still has costly presentation work to complete.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How do you confirm an improvement in the field?
After changing code, repeat the same local interaction recording and check whether the stage identified in the original trace improved. A faster lab trace is useful evidence for that flow, but it does not establish the experience of every user or device.
Continue monitoring field outcomes, including the 75th-percentile INP for mobile and desktop. Use the field data to check that the improvement persists for real visits and that another interaction or device group has not become the remaining problem. No single generic code technique guarantees an INP improvement on every site; the trace and field results determine whether a change helped.
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