Break INP into input delay, processing and presentation delay.
INP replaced First Input Delay because it measures every interaction rather than only the first. A large input delay means the main thread was already busy when the user acted. Long tasks are the usual cause of poor INP, and breaking work into chunks under 50 ms is the standard remedy.
Interaction to Next Paint
INP = input delay + processing time + presentation delay
INP = input delay + processing time + presentation delay INP replaced First Input Delay because it measures every interaction rather than only the first. A large input delay means the main thread was already busy when the user acted.
Long tasks are the usual cause of poor INP, and breaking work into chunks under 50 ms is the standard remedy.
This calculator takes 4 inputs: Input delay, Event processing time, Presentation delay, Long tasks blocking the main thread. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.