When the Federal Reserve weighs whether to raise, cut or hold interest rates, the inflation number it is officially watching is probably not the one you saw in the headlines. That number is the Personal Consumption Expenditures price index, or PCE — published each month by the U.S. Bureau of Economic Analysis (BEA) as part of its Personal Income and Outlays report. Understanding it explains a lot about how monetary policy actually works.

The Fed's chosen yardstick

The PCE matters above all because it is the Fed's official target. Since January 2012, the Federal Open Market Committee — the body that sets U.S. interest rates — has stated that inflation of 2% a year, "as measured by the annual change in the price index for personal consumption expenditures," is most consistent over the long run with its goals of stable prices and maximum employment. That 2% PCE figure is the benchmark every rate decision is judged against.

Headline vs. core

The PCE comes in two main forms. Headline PCE covers all consumer spending — food, gasoline, rent, healthcare, streaming subscriptions. Core PCE strips out food and energy, two categories whose prices swing sharply with weather, harvests and geopolitics. Economists watch core PCE closely because it better reveals the underlying inflation trend rather than a temporary jump at the pump or the grocery store. When Fed officials talk about persistent inflation, they usually mean core.

How PCE differs from the CPI you hear about

The inflation figure that dominates the news is the Consumer Price Index (CPI), published by the Bureau of Labor Statistics. PCE and CPI measure similar things but are built differently — and the construction choices matter.

Scope. CPI captures what urban households pay out of their own pockets. PCE casts a wider net, counting spending made by and on behalf of households. The clearest example is healthcare: if your employer's insurance or a government program pays your medical bill, that shows up in PCE but not in CPI. That makes PCE a fuller picture of what is actually consumed.

Weights. Because the two track different spending universes, they weight categories differently. The biggest gap is housing: shelter carries roughly 34% of the CPI basket but only about 16% of PCE, according to San Francisco Fed researchers. When rents climb fast, CPI tends to rise faster than PCE partly for that mechanical reason.

Substitution. CPI uses a formula that holds the basket relatively fixed. PCE updates its weights monthly, capturing the way shoppers swap to cheaper options when prices rise — ground beef instead of steak, a store brand instead of a name brand. That behavior, called the substitution effect, means PCE usually registers slightly lower inflation than CPI under the same conditions. Since 2000, CPI inflation has run on average about 0.39 percentage points a year above PCE, though the gap widens and narrows over time.

Why the Fed picked it

The Fed settled on PCE because it judged the index more comprehensive, more responsive to how people actually spend, and more consistent over time. As the St. Louis Fed puts it, PCE "accounts for how Americans are spending their money at a given time and more quickly adapts to changes in spending patterns." The choice is a methodological judgment about which measure best reflects the price environment facing consumers — not an attempt to make inflation look smaller.

What it means for you

For households, the practical point is that the figure on the evening news (CPI) and the figure the Fed targets (PCE) can diverge, sometimes meaningfully. If CPI is running at 3.5% while core PCE sits at 2.8%, the Fed may see price pressure as less severe than the headline implies.

For investors, each monthly PCE release is a direct signal. A core PCE reading well above 2% has historically gone hand in hand with the Fed leaning toward higher rates or holding them up; a reading drifting back toward 2% opens the door to cuts. Neither index is "wrong" — they answer slightly different questions. Knowing which one the Fed is actually steering by makes the central bank's moves far easier to read.