Glossary term
What is FID (First Input Delay)?
FID stands for First Input Delay.
The old speed metric. It measured only the wait before the first click was handled. INP replaced it.
Learn it properly · The Browser ContractLesson 9: Core Web Vitals for Engineers: LCP, INP and CLSWhat each metric measures, its “good” limit at the 75th percentile, why INP replaced FID, and the difference between field data and lab data.