Last edited Sun May 12, 2024, 10:06 AM - Edit history (1)
For the 3 month period Dec'23 to Mar'24 (and using $10,000 for more accuracy to compare to CUSR0000SA0 )
https://data.bls.gov/cgi-bin/cpicalc.pl?cost1=10000.00&year1=202312&year2=202403
Result: $10,182.11 which is a 1.8211% increase which DOESN'T MATCH THE BELOW and I don't know why not.
CPI (aka CUSR0000SA0 in this post):
https://data.bls.gov/timeseries/CUSR0000SA0
Click on "MORE FORMATTING OPTIONS" and click the following checkboxes: "original data value", "3 month percent change", and "12 month percent change" checkboxes, and then click the Retrieve Data button.
On the 3 month one it shows 1.1% for March 2024
Using the original data values
The 3 months to March 2024 is 312.230/308.742 = 1.01130 = 1.130% = 1.1% rounded
Back to the inflation calculator:
from above: "Result: $10,182.11 which is a 1.8211% increase"
This annualizes to 7.2844% if one multiplies by 4 (which nearly matches the 7.24% in your OP), or more correctly: 1.018211^4 = 1.074858 -> 7.4858% ->7.49%.
Again I don't know why, for the non-annualized 3 month increase, that the inflation calculator (1.82%) doesn't match with CUSR0000SA0 (1.13% or 1.1%)
Note that for the 12 month increase of March '23 to March '24 I did have a match in all the numbers (the inflation calculator agreed with CUSR0000SA0 -- see my post#2 above)
Edited to add - by the way, the 3 month ANNUALIZED increase using the CUSR0000SA0 original data value numbers:
The 3 months to March 2024 is 312.230/308.742 = 1.01130 (as above). Annualizing: 1.01130^4 = 1.04597 -> 4.597% -> 4.60%
On the corresponding CORE CPI number, the 3 month annualized average is 4.53%.
CORE CPI: http://data.bls.gov/timeseries/CUSR0000SA0L1E