INP (Interaction to Next Paint) measures how quickly a page responds to user interactions, and replaced FID as the responsiveness metric in Core Web Vitals. On paid pages, especially on mobile, a slow response to taps and clicks costs conversions.
The essentials in a definition
INP is a Core Web Vitals metric that measures a page’s responsiveness to user interactions. Better values mean faster, smoother interactions. On paid landing pages, it relates to conversion, and the official documentation describes measurement and thresholds.
What INP measures
INP observes the time between an interaction (click, tap, key) and the next visual update, across the visit, and reports a representative value of the slowest interactions. It is part of Core Web Vitals, with thresholds published by Google to classify it as good, needs improvement or poor. Consult current values in the official documentation.
Unlike loading metrics, INP reflects the experience during use: opening menus, choosing variants, filling forms, adding to cart.
Common causes on paid pages
Excess third-party JavaScript (tagging, chats, A/B tests, widgets), long tasks on the main thread, heavy interface updates and poorly optimised components. On campaign pages, scripts added over time accumulate and nobody reviews them.
On mid-range phones, these problems are more visible than on the team’s computer.
From measurement to responsiveness gain
- Measure INP by page and device
- Identify scripts and long tasks
- Optimise critical interactions
- Validate with field data
How to improve
Measure with real (field) data and then diagnose in the lab. Reduce and defer non-essential scripts, break up long tasks, simplify the code of critical interactions and avoid blocking visual response. Test the components that matter most for conversion: form, buy button, filters.
Also consider accessibility: responsive, predictable interfaces benefit all users, including those using assistive technologies.
A page that responds slowly loses the click you already paid for.
Prioritise with the business
Not all pages deserve the same effort. Start with those with the most paid traffic and those containing the main action. Compare conversion by performance class to understand the expected gain and justify the investment.
Keep a performance budget for new scripts and review it for each campaign.
Decision table
| Source of slowness | Symptom | Response |
|---|---|---|
| Third-party scripts | Clicks with no immediate reaction | Remove or defer the non-essential |
| Long tasks | Blocked interface | Split and optimise code |
| Heavy components | Slow filters and menus | Simplify and test on phones |
| Forms | Delay when typing | Reduce event logic |
Common mistakes to avoid
- Optimising only on desktop. The mid-range phone reveals the real problems.
- Accumulating scripts without review. Each one adds cost.
- Measuring only in the lab. Field data show what users experience.
How to measure the result
Track field INP, conversion by performance class and the number of scripts per page.
Limits and exceptions
Metric improvement does not always translate into more conversions, and other factors influence results. Thresholds and how to measure may be updated by Google; confirm official documentation. Changes to live pages should be tested first.
Illustrative example
Illustrative example: a store sees its product page, with a lot of paid traffic, has poor INP on mobile. It removes two non-essential scripts, defers a chat widget and simplifies the variant selector. After a few weeks, field data improve and add-to-cart rate rises, although other factors may contribute.
In practice: checkpoints
Review INP monthly for the main templates and after every release, and record the changes that improved or worsened it.
Frequently asked questions
Does INP directly affect ads?
It affects page experience and therefore conversion; the relationship with search performance should be read in the official documentation.
What value is good?
Consult the current thresholds published by Google; avoid numbers from memory.
Can I measure without developers?
You can see field reports; improving usually requires technical support.
How often should I measure?
Continuously in field data and after each relevant change.
Does INP replace other metrics?
It complements loading and stability metrics; all count.
INP measures responsiveness to interactions; improve it by reducing scripts, long tasks and heavy components on the pages with the most paid traffic, and validate with field data.
Sources and recommended reading
Last editorial review: October 2026. Informational content; always confirm current conditions in the official sources before deciding.