Interaction to Next Paint (INP)
Also known as: INP
A Core Web Vitals metric that measures responsiveness by timing how long a page takes to visually respond to user interactions like clicks, taps, and key presses across the whole visit. It reports the worst representative delay; a good score is 200 milliseconds or less. It replaced First Input Delay in 2024.
Key Takeaways
- Interaction to Next Paint is a Core Web Vitals metric that measures how long a page takes to visually respond to user interactions.
- It observes clicks, taps, and key presses across the whole visit and reports a worst representative delay.
- A good INP score is 200 milliseconds or less; above 500 milliseconds is considered poor.
- INP replaced First Input Delay as a Core Web Vitals metric in March 2024.
- Heavy JavaScript on the main thread is the most common cause of poor INP, and breaking up long tasks helps.
How It Works
Interaction to Next Paint measures responsiveness during real use. Each time a user interacts, the browser records how long it takes from the interaction until the next frame paints, reflecting the visible response. INP reports a representative worst-case value across the whole visit, so it captures sustained snappiness, not just the first tap.
As one of the Core Web Vitals, INP became the responsiveness metric in 2024, replacing First Input Delay, which only measured the first interaction's input delay. INP is broader because it includes processing and rendering time for many interactions.
INP is distinct from the other vitals: Largest Contentful Paint measures loading speed, and Cumulative Layout Shift measures visual stability. To improve INP, reduce main-thread work, split long JavaScript tasks, defer non-critical scripts, and keep event handlers lean so the browser can paint a response quickly.
Why It Matters
INP reflects how snappy a page feels during real use, not just at load. Slow interactions signal a sluggish experience, and because INP is a ranking signal, poor responsiveness can cost both users and rankings.
Example
A SaaS site has a filter panel that feels laggy. Field data shows an INP of 480 milliseconds because a large handler runs synchronously on every click, blocking the main thread. The team defers analytics scripts, breaks the handler into smaller async tasks, and trims a third-party widget. INP drops under 200 milliseconds, and the interface feels immediate.
Common Mistake
Running heavy JavaScript on the main thread that blocks the browser from responding to input. Large third-party scripts and unoptimized event handlers are frequent causes; break up long tasks to fix it.
Frequently Asked Questions
What is a good INP score?
An INP of 200 milliseconds or less is considered good. Between 200 and 500 milliseconds needs improvement, and above 500 milliseconds is poor. The threshold is based on the 75th percentile of page loads for real users.
How is INP different from First Input Delay?
First Input Delay only measured the input delay of the first interaction. INP measures the full latency, including processing and rendering, across all interactions in a visit, giving a more complete picture of responsiveness. INP replaced FID in 2024.
How do I improve INP?
Reduce main-thread work. Break long JavaScript tasks into smaller pieces, defer or remove non-critical and third-party scripts, and keep event handlers lightweight. Minimizing what runs synchronously during interactions lets the browser paint a response faster.
Is INP a ranking factor?
INP is part of Core Web Vitals, which Google uses as part of its page experience signals. It is one modest factor among many, so improving it can help, but content relevance and quality still matter far more for rankings.