Core CPI.
In plain English
The Bureau of Labor Statistics publishes both headline CPI, which covers everything households buy, and core CPI, which excludes the food and energy categories. Those two categories swing hard on weather, harvests, and oil markets, and their moves often reverse within months. Stripping them out makes the persistent part of inflation easier to see. Core is not what anyone actually pays, since households do buy groceries and fill gas tanks. It is a signal-extraction tool, not a cost-of-living measure.
01Why it matters
Policymakers set rates off core readings while households experience headline prices, which is why officials can describe inflation as cooling while your grocery bill keeps climbing.
02The math, step by step
Say headline CPI rises 3.4 percent over a year while core rises 2.8 percent. The 0.6-point difference means food and energy rose faster than everything else. If oil prices then fall back, headline can drop below core without core moving at all.
Illustrative example. The amounts here are hypothetical, chosen to show how the math works, not real quoted rates or figures.
03What this is NOT
Headline CPI includes food and energy and is the number used for most cost-of-living adjustments. Core CPI removes them to reveal the trend. Neither is more correct. They answer different questions: what people pay, versus where inflation is heading.
04Receipts
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Plain-English answers from our glossary. Receipts included. Never advice.
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