About this indicator
About
Core CPI strips food and energy out of the headline Consumer Price Index. The Bureau of Labor Statistics publishes it alongside headline CPI on the same release. The intent is to filter the noisiest categories so the underlying inflation trend is easier to read. Core is what the Fed cites most often when explaining its rate decisions, even though the headline is what consumers actually pay.
Why it matters
Energy and food prices swing on weather, OPEC, and harvests — variables monetary policy can't reach. Core CPI is the part of the basket that responds to wages, rents, and demand. The federal funds futures market reprices most sharply on core surprises. A persistent gap between core CPI and core PCE (the Fed's preferred measure) tells you which side of the Fed's reaction function is leaning. Most market commentary refers to year-over-year core; the FOMC's policy framework explicitly tracks 3-month and 6-month annualized rates for early-trend detection.
How it's computed
Core CPI is a direct subtraction from the same 80,000-quote sample as headline CPI: BLS publishes the index with the food-at-home, food-away-from-home, and energy components dropped out. The remaining weights are renormalized. Shelter (rent of primary residence plus owners' equivalent rent) makes up roughly 42% of the core basket, which is why housing inflation dominates the core series.
Pitfalls
Core's shelter weight makes it a lagging measure: market rent on new leases turns months before BLS's stock-based survey catches it. The Cleveland Fed's Median CPI and Trimmed-Mean CPI exist to handle the shelter lag. Treating core as a noise-free signal is the most common mistake; it just has different noise than headline.