On August 2020 the Federal Reserve changed their inflation policy to a Flexible Average Inflation Targeting (FAIT) policy.

The new inflation policy seeks to get a inflation rate of 2% over time.

"the statement adopts a flexible inflation averaging strategy that seeks to achieve inflation that averages 2 percent over time in order to ensure longer-term inflation expectations are well anchored at 2 percent"

Moreover, the new policy does not define a particular formula to calculate inflation over time

"In seeking to achieve inflation that averages 2 percent over time, we are not tying ourselves to a particular mathematical formula that defines the average. Thus, our approach could be viewed as a flexible form of average inflation targeting." Jerome Powell, August 27, 2020

Therefore, one can assume, since the Federal Reserver has no formula, that the FOMC will look back at some time frame, 24 months ex, and get the average inflation for the look back time period.

All Scripts to calculate the Inflation can be found here

Inflation

Inflation Over Time