CPI is the Consumer Price Index — a monthly number that tracks what a fixed basket of household purchases costs, so its change over time is a measure of inflation. The current CPI-U index level is 336.9 for Sep '26, which is +4.00% higher than a year earlier.
Each category carries a weight reflecting how much of the average urban household budget it takes up. Housing dominates, which is why shelter costs move the headline number more than anything else.
CPI stands for Consumer Price Index. It is a monthly measure of the average change in prices that households pay for a representative basket of goods and services, published in the United States by the Bureau of Labor Statistics.
It measures price change, not price level. The index tracks the cost of the same basket over time — housing, food, energy, transportation, medical care, apparel, recreation, education and communication — so the change from one period to another is the inflation households experience on average.
The index is anchored so that the average of 1982 to 1984 equals 100. An index of 320 therefore means the basket costs about 3.2 times what it did in the early 1980s. Index numbers make it easy to compare periods and categories that use completely different units.
Social Security cost-of-living adjustments, many union and rental contracts, tax bracket indexing, and Federal Reserve policy discussion all reference consumer price measures. Businesses use it to escalate contracts and to deflate revenue into real terms.
Core CPI is the same basket with food and energy removed, because those two categories are volatile enough to hide the underlying trend in any single month. Headline CPI is what people actually pay; core CPI is what analysts watch for direction.
CPI comes from the Bureau of Labor Statistics and reflects out-of-pocket urban household spending. PCE comes from the Bureau of Economic Analysis, covers a broader set of spending including costs paid on households' behalf, and reweights the basket faster. The Federal Reserve's 2 percent target refers to PCE.
Only loosely. CPI is an average across urban households. If your rent, commute or medical spending is far from the average weighting, your personal inflation rate can differ substantially from the headline figure.