Every month, the United States publishes not one but two headline inflation gauges — and they often disagree. On October 14, the Bureau of Labor Statistics (BLS) reported that consumer prices rose 3.7% in the 12 months through September 2026, with core prices up 2.6%. Yet the Federal Reserve’s official inflation target is not tied to that number at all. It is tied to a different index, the Personal Consumption Expenditures (PCE) price index, whose latest reading — 3.4% headline and 3.0% core for August — came from the Bureau of Economic Analysis (BEA) on September 30. The September PCE report is scheduled for October 29.

Two gauges, two agencies, two answers. Understanding why they differ is essential to reading every inflation headline — and to understanding what the Fed will do next.

Two gauges, one economy

The Consumer Price Index (CPI) is the older and more famous of the two. Compiled by the BLS, it tracks the out-of-pocket spending of urban households on a fixed basket of goods and services: rent, groceries, gasoline, clothing, medical care and more. Each month the BLS collects roughly 80,000 prices across 75 urban areas, and the index is expressed against a 1982–84 base of 100. Because it measures what households actually pay, the CPI is written into law and contracts everywhere: it sets Social Security cost-of-living adjustments, adjusts federal tax brackets, and underpins inflation-protected Treasury bonds.

The PCE price index, compiled by the BEA, takes a broader view. It covers spending by households and spending made on their behalf — including employer-paid health insurance and government programs such as Medicare and Medicaid — as well as spending by nonprofit institutions serving households. In total it covers a substantial share of the economy: personal consumption expenditures make up roughly 70% of GDP. Its weights shift every period to reflect what people actually buy, and its history is revised as better data arrive.

Both gauges come in headline and “core” versions. Core strips out food and energy, the two categories most exposed to supply shocks, and is the version policymakers watch most closely month to month.

Four reasons the numbers differ

The BLS and BEA themselves attribute the gap between the two indexes to four effects. Each one matters at different times.

1. Scope. The CPI counts only what urban households pay out of pocket. The PCE counts a wider universe, and the difference is most visible in health care: medical services paid by employers or government count in PCE but not in CPI. That is why health care carries far more weight in PCE than in CPI.
2. Weights. Because their baskets differ, the same price move hits each index differently. Shelter is the biggest single item in the CPI — roughly a third of the basket — but only about a sixth of PCE, since PCE’s broader scope dilutes housing. When rents are the main driver of inflation, CPI tends to run hotter; when health care costs surge, PCE feels it more.
3. Formula. The CPI uses a Laspeyres-type formula: it holds the basket roughly fixed and reprices the same items each month. The PCE uses a chained Fisher formula that lets weights move as consumers substitute — if beef gets expensive and shoppers switch to chicken, PCE captures that switch and CPI does not. Because substitution usually dampens measured price rises, the formula effect tends to push CPI above PCE. On average over time, CPI inflation runs about 0.3 to 0.5 percentage points above PCE inflation.
4. Revisions and other differences. The CPI is essentially never revised once published (apart from seasonal factors). PCE is revised every year, and sometimes substantially. The September 30, 2026 release carried the BEA’s annual update, which rewrote data back to January 2021 and cut July 2026 PCE inflation from 3.7% to 3.4% headline and from 3.3% to 3.0% core. A reader comparing an old PCE print with a new one can easily be comparing two different vintages of history.

The latest readings — and an unusual inversion

The table below puts the two gauges side by side. August 2026 is the latest month for which both have been published, so it is the only clean apples-to-apples comparison. September CPI is the latest CPI print; September PCE is still to come.

Sources: BLS CPI release, October 14, 2026; BEA Personal Income and Outlays, August 2026 (BEA 26–43), September 30, 2026. September PCE is scheduled for October 29, 2026, at 8:30 a.m. ET. See also the BLS/BEA comparison paper and the FRED blog.

Two things stand out. First, headline CPI and PCE were identical in August — a rare convergence. Second, the core gap is inverted: core PCE (3.0%) sits above core CPI (2.4%), the opposite of the usual pattern in which CPI runs higher. The gap between the two gauges is not a fixed spread; it swings with which categories are hot and with revisions. September’s CPI jump, driven by a 9.1% monthly surge in gasoline that accounted for more than half of the headline increase, is exactly the kind of energy-driven move that lifts CPI without necessarily lifting PCE by the same amount. Whether September PCE confirms that jump — or shows a milder core reading — is the next data point that matters.

Why the Fed targets PCE

Since January 2012, the Federal Open Market Committee (FOMC) has defined its 2% inflation objective in terms of headline PCE, not CPI. The Fed’s reasoning, set out when the target was adopted, is that PCE covers a broader range of spending, its weights better reflect what consumers actually buy, and its history can be revised and improved. Core PCE, which strips out food and energy, is the guide policymakers watch most closely between meetings, because it is less hostage to one month’s gasoline price.

That choice has a practical consequence for anyone translating headlines into rate expectations: 2% PCE inflation does not mean 2% CPI inflation. Given the long-run tendency for CPI to run roughly 0.3 to 0.5 points above PCE, a PCE reading at target is consistent with CPI inflation of roughly 2.3% to 2.5%. Judging the Fed against a CPI print alone will almost always make policy look further from target than it is.

For the full picture of how the Fed turns these readings into rate decisions — the federal funds rate, the FOMC, the dot plot and market pricing — see our complete guide: How the Fed Sets Interest Rates: A Complete Guide.

Why markets still move on CPI first

If the Fed watches PCE, why does CPI dominate headlines? Timing. The CPI lands in the middle of the month, roughly two weeks before the PCE report for the same month. September CPI arrived on October 14; September PCE is not due until October 29. For traders, businesses and households, CPI is simply the first read on the month — and it is the gauge embedded in wage contracts, tax brackets and bond payments.

September’s CPI report showed why that first read can move markets: headline inflation accelerated from 3.4% to 3.7%, above the 3.6% consensus, and core rose from 2.4% to 2.6%, also above expectations. That combination — an energy-led headline jump plus a firmer core — complicated the debate heading into the FOMC’s October 27–28 meeting, where officials must decide whether to hold the federal funds target range at 3.75%–4.00% and what to signal for December. A Reuters survey conducted October 16–20 found 94 of 100 economists expected no move in October. Our coverage of the September CPI report and the debate it triggered is here: Hot September CPI Lifts Fed October Hike Odds. For how Fed officials reacted to the preceding wholesale inflation data, see Fed Officials Cool October Hike Bets After Hot PPI.

What to watch next

Three dates frame the next chapter of this story. On October 29, the BEA releases September PCE: watch whether core PCE stays above core CPI, and whether headline PCE confirms the energy-driven jump in CPI. On October 27–28, the FOMC meets with the target range at 3.75%–4.00% after September’s quarter-point increase; the statement and Chair Kevin Warsh’s press conference will show how much weight officials put on the CPI overshoot versus the softer, revised PCE path. And through the rest of the year, watch the revisions: PCE history has already been rewritten once this autumn, and the next annual update could move the story again.

The deeper lesson is simpler than the acronyms suggest. There is no single “true” inflation rate. There are two carefully built lenses on the same economy, each with its own blind spots — one that sees what households pay, and one that sees what the whole economy spends. Read them together, and the picture gets sharper. Read either one alone, and it does not.

Frequently asked questions

Which measure is the “real” inflation rate?

Neither, on its own. CPI best captures the out-of-pocket cost pressure households feel, which is why it governs cost-of-living adjustments. PCE best captures economy-wide price change, which is why the Fed targets it. The honest answer to “how bad is inflation?” usually requires both numbers and the gap between them.

If the Fed targets 2% PCE, what CPI reading equals success?

Roughly 2.3% to 2.5%, given the long-run average gap of 0.3 to 0.5 points. That translation is approximate, not a rule — the gap has been zero on headline in August 2026 and negative on core, so any single month can deviate.

Can a PCE number I already read change later?

Yes. PCE is revised in annual updates and in comprehensive revisions, sometimes materially — the September 2026 update cut July headline PCE by 0.3 points. CPI, by contrast, is published once and left alone, which is one reason it anchors contracts.

Which gauge affects my Social Security check?

CPI. Social Security cost-of-living adjustments are tied to a CPI variant, not to PCE. Proposals to switch the adjustment to a chained index would change that link, which is why the CPI-versus-PCE debate occasionally becomes a political one.

Macrometer explains the economic data behind the headlines. This article is for information only and is not financial advice.