Core Web Vitals in Detail
What is the relationship between INP and the former FID metric?
Answer
INP (Interaction to Next Paint) replaced the FID (First Input Delay) metric as a Core Web Vital in March 2024. FID measured only the response time of the very first user interaction. INP, however, captures the response time of all interactions throughout the entire page visit and returns the worst value (minus statistical outliers). This makes INP significantly more meaningful than FID, as a page may respond quickly on the first click but become blocked during later interactions. For optimization, this means: not just the initial page load needs to be fast, but the entire interaction chain.