First Input Delay (FID) was a Core Web Vitals page speed metric that measured how long a page took to start responding to a visitor’s first interaction. In March 2024, Google replaced it with Interaction to Next Paint (INP), which measures the responsiveness of all interactions on a page. A good INP is 200 milliseconds or less (Google, web.dev). Check your pages with our free website speed test.
Key takeaways
- INP replaced FID as a Core Web Vital in March 2024.
- FID looked only at the delay before the first interaction was processed. INP looks at all interactions during a visit.
- A good INP is 200 ms or less. Over 500 ms is poor.
- In lab tests, Total Blocking Time (TBT) is the closest stand-in for INP.
What is FID in page speed?
FID (First Input Delay) measured the time between a visitor’s first interaction, such as a tap or click, and the moment the browser could begin to respond. It only looked at the delay of the first interaction, not at how long the response took, and not at later interactions. A good FID was 100 milliseconds or less.
What is INP?
INP (Interaction to Next Paint) measures how quickly a page visibly responds after an interaction such as a click, tap or key press. It considers the interactions during the whole visit and reports a value that reflects the slowest ones, so it shows how responsive the page feels throughout.
What is the difference between FID and INP?
| Feature | FID | INP |
|---|---|---|
| Status | Replaced in March 2024 | Current Core Web Vital |
| Interactions measured | First only | All interactions during the visit |
| What it measures | Delay before processing starts | Time until the next visible update |
| Good value | 100 ms or less | 200 ms or less |
| Poor value | Over 300 ms | Over 500 ms |
What is a good INP?
An INP of 200 milliseconds or less is good. Between 200 and 500 ms needs improvement, and over 500 ms is poor. Google judges this at the 75th percentile of real visits. See our guide to the Core Web Vitals test and website performance metrics.
How do you measure INP?
INP is a real-user metric, so look at field data in Google PageSpeed Insights or the Core Web Vitals report in Search Console. In a lab test you will see Total Blocking Time instead. For debugging, use the Performance panel in Chrome DevTools. See how to use Google PageSpeed Insights.
How do you improve INP?
- Remove JavaScript you do not use.
- Break up long tasks, so the browser can respond between them.
- Delay third-party scripts such as chat widgets and trackers.
- Keep pages and their HTML structure small, because large pages take longer to update.
- Avoid heavy work when someone taps a button, such as large layout changes.
- Test again on a mid-range phone, not only on a fast computer.
For the full list of fixes, see how to improve website speed.
Does INP affect SEO?
INP is part of the Core Web Vitals, which Google uses in its page experience signals. Relevant content still matters most, so treat INP as a way to improve the experience for visitors.
Frequently asked questions
Is FID still a Core Web Vital?
No. INP replaced FID in March 2024.
Why did Google replace FID with INP?
FID only captured the first interaction’s delay. INP covers all interactions and the time until the page updates, which reflects real responsiveness better.
What is a good FID?
FID of 100 ms or less was good, but it is no longer a Core Web Vital.
Is Total Blocking Time the same as INP?
No. TBT is a lab metric that tends to move with INP, but INP comes from real visitors.
Why is my INP high on mobile?
Phones process JavaScript more slowly than computers, so heavy scripts show up more.
Conclusion
FID is gone, and INP is the Core Web Vital for responsiveness: 200 milliseconds or less is good. Reduce JavaScript, break up long tasks and delay third-party scripts. Check your pages with our free website speed test.
