Calculate CLS from impact and distance fractions for each shifting element.
Each shift contributes the product of how much of the screen moved and how far. Reserving space for images and ads eliminates most shifts entirely, since the impact fraction becomes zero. CLS is the easiest Core Web Vital to fix because setting explicit dimensions on media removes the shift rather than merely speeding it up.
Cumulative Layout Shift
Layout shift score = impact fraction × distance fraction, summed across shifts
Layout shift score = impact fraction × distance fraction, summed across shifts Each shift contributes the product of how much of the screen moved and how far. Reserving space for images and ads eliminates most shifts entirely, since the impact fraction becomes zero.
CLS is the easiest Core Web Vital to fix because setting explicit dimensions on media removes the shift rather than merely speeding it up.
This calculator takes 4 inputs: Impact fraction of shift 1, Distance fraction of shift 1, Impact fraction of shift 2, Distance fraction of shift 2. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.