Among the many issues facing the public and financial markets, the impact of President Trump’s tariffs on inflation and how they affect the Federal Reserve’s monetary policy stand out. Estimates of the economic and inflation impacts of the tariffs are quickly evolving as the twists and turns of Trump’s policies change the magnitudes and character of the tariffs. This short note doesn’t speculate on the magnitude of the tariffs, rather it considers how CPI and PCE inflation will likely be affected differently. These differences may influence Fed behavior.
PCE inflation measures the percentage change in prices of all consumer goods and services. This includes all goods, including those paid for by consumers as well as those financed by third party payments like Medicare, Medicaid and medical services paid for by employer insurance. CPI inflation measures the percentage change in prices of goods and services directly paid for by consumers and excludes goods and services paid for by third parties.
As such, PCE and CPI inflation measure the price changes of different baskets of goods and services. PCE inflation is a broader measure of inflation, while the CPI is a better measure of consumer out-of-pocket expenses. The CPI comprises a much larger share 35.4% of shelter costs (including rental costs and owners’ equivalent rent, OER) than the PCE, and a smaller share of medical care (8.3%). Both measures of consumer prices include items like personal care and education expenses.
Of note, both the PCE and CPI inflation measures are adjusted for estimates of quality improvement. The quality adjustments are estimated by the Bureau of Economic Analysis within the U.S. Department of Commerce, based on hedonic regression analyses that try to capture the quality improvements of new products, other estimating techniques, and some degree of subjectivity.
While CPI and PCE inflation are the most widely used measures of inflation, the GDP deflator is a broader measure of inflation that captures the price changes in other components of GDP, including business fixed investment, imports and exports, and residential investment (new construction and home improvements). This is important in the current context, since a sizable portion of imported goods that are subject to tariffs are capital goods purchased by domestic businesses and used in production.
An historical note. The Fed’s semi-annual Monetary Policy Report to Congress and its central tendency projections of economic growth and inflation, which began in 1980 as required by the Full Employment Act of 1978, used the GDP deflator as its inflation measure until 1990, when it switched to the CPI; Fed Chair Greenspan subsequently switched it to the PCE. The Fed’s first-ever Strategic Plan of 2012 officially established the PCE inflation target of 2%.
All other government agencies--and all other central banks in the world--rely on CPI inflation, and the CPI is an important “policy variable” used in various functions, including to index the benefits of Social Security, other pensions and an array of other programs. The Fed began focusing on core inflation early on: Fed Chair Arthur Burns instructed his research staff in the mid-1970s to calculate the CPI excluding food and energy following the spike in agricultural prices in 1971-1972 and surging oil prices generated by the first Arab Oil Embargo in November 1973. His primary interest was to tell the public that the high inflation was caused by exogenous forces. He was also attempting to quell rising inflationary expectations and bond yields without having to tighten monetary policy too much (Remember, before May 1983, mortgage rates were calculated directly in the CPI).
Recent CPI and PCE inflation trends. CPI inflation has been materially higher than PCE inflation in the post-Covid economy, as shown in Chart 1. CPI inflation was 0.6 percentage points higher than PCE inflation in 2024 (3.4% vs 2.8%), 0.7 ppt higher in 2023 (4.8% vs 4.1%) and 0.8 ppt higher in 2022 (6.1% vs 5.3%). So far in 2025, they have tracked closer. The cumulative differences have added up: since December 2019, the CPI index has risen by 3.8 percentage points more than the PCE price index Chart 2). As we all know, the large rise in the general price level has resonated with American citizens and created a communications problem with the Fed.