First Input Delay
First Input Delay, FID, measured the time from a visitor’s first interaction to the moment the browser began processing it. It was a Core Web Vital until March 2024, when Interaction to Next Paint replaced it. If a report still shows FID, the report is out of date.
By Théophile Louvart, founder of Porteur · Updated 15 September 2026 · Markdown
Why it was replaced
| First Input Delay | Interaction to Next Paint | |
|---|---|---|
| Interactions measured | The first one only | Every click, tap and key press |
| What it timed | The wait before processing began | The wait, the processing, and the paint |
| Typical result | Most pages passed | Slow pages fail, as they should |
| Status | Retired in March 2024 | A Core Web Vital |
FID measured only the delay before the handler started, on the first interaction. A page could pass while every button took a second to show a result, because the work after the handler started was never counted.
What to work to now
- Interaction to Next Paint: good up to 200 ms, poor above 500 ms, measured on real visitors.
- Total Blocking Time is the lab stand-in, since a lab run cannot click anything.
- The causes are the same ones FID hinted at: long tasks on the main thread, heavy handlers, hydration of large frameworks, third-party scripts.
Where the old number went
Search Console
The Core Web Vitals report shows LCP, CLS and INP. FID is gone from it.
PageSpeed Insights
The field section shows INP where there is enough traffic. Old screenshots in blog posts still show FID.
Your own reporting
If a dashboard still collects FID from the web-vitals library, switch the metric to INP so the numbers mean something.
Questions
No. Interaction to Next Paint replaced it in March 2024. Reports and articles that still feature FID predate that change.
FID timed only the delay before the browser began handling the first interaction. INP measures every interaction and includes the processing and the paint, then reports the slowest.
Up to 200 ms is good and above 500 ms is poor, measured at the 75th percentile of real visitors over 28 days.
Because it measured so little: the wait before a handler started, on one interaction. A page could be slow in every way that a visitor feels and still pass.
The work is the same and the bar is higher: fewer and smaller scripts, shorter tasks on the main thread, and painting the visible change before doing the rest of the work.
Check my site, free
The free check measures how your home page loads and responds on a simulated phone, then names the first thing worth fixing.
- Free check, no card
- Read-only, your own accounts
- Readable by your agent
Read next
- GlossaryInteraction to Next Paint (INP)
- GlossaryCore Web Vitals
- GuideHow to improve Interaction to Next Paint
- GuideTotal Blocking Time: the lab number that stands in for INP
- GuideCore Web Vitals for a product site: the three numbers
- GuideThe Core Web Vitals report in Search Console, page group by page group
- Free toolCore Web Vitals checker
- GlossaryTime to first byte