Forex Fundamentals
Forex Economic Indicators

What Is Core Inflation?

By Rutger Lokin · Updated

What is core inflation? It is the inflation rate with food and energy prices taken out. In the US those two make up about a fifth of the consumer price basket, and they cause much of its month-to-month noise.

Petrol can jump on an oil headline and fall back a month later. That tells you a lot about oil and very little about whether prices across the economy are rising faster. Core strips it out so you can see the part that tends to stay: rents, insurance, haircuts, doctor’s bills.

Two Junes, a year apart

The clearest way to see why core exists is to put two US CPI reports side by side (BLS, June 2022; BLS, June 2023).

  • June 2022: energy prices were up 41.6% on the year. Headline CPI was 9.1%, core 5.9%. The headline made the rest of the basket look hotter than it was.
  • June 2023: energy was down 16.7%. Headline CPI was 3.0%, core 4.8%. Now the headline made things look cooler than they were.

If you read only the headline in the summer of 2023, inflation had fallen from 9.1% to 3.0% and looked nearly done. Core had come down from 5.9% to 4.8%. Much of what was left was housing: in June 2023 shelter alone accounted for over 70% of the monthly rise in the all-items index.

The core measures traders watch

The next reports are on When is the next US CPI report? and When is the next PCE report?

If core is cleaner, why is it not the target?

The Federal Reserve’s 2% goal is set on headline PCE, food and energy included. Its reasoning is simple: food and energy are a real part of household budgets, and in the end it is overall prices the Fed wants to keep stable. Core measures, it says, “can be useful in assessing inflation trends” (Federal Reserve FAQ).

So the Fed is judged on headline and steers by core. An energy shock drops out of the yearly rate twelve months later, and once energy prices stop swinging, headline and core drift back toward each other.

When the two disagree on the day

They do sometimes point opposite ways on the month, and nearly always the same way round. Of the 233 months from March 2007 to September 2026, US headline CPI was first published as a fall on the month in 35. In 24 of those 35, core still rose, most recently in the reports for December 2022, June 2024 and March 2025. The opposite, headline up and core down, happened once, in January 2010. So a monthly fall in the headline has more often than not left the rest of the basket still getting dearer.

That count compares the one-month changes in the seasonally adjusted indexes as the BLS first published them, kept by the St. Louis Fed (CPI, core CPI), rounded to one decimal as the BLS prints them. Thirty-five months is a small sample, and the seasonal factors are revised every year: on today’s figures the same count gives 18 of 26.

Here is a made-up report. Headline CPI comes in below the forecast, core comes in above it. The soft headline says inflation is cooling. The firm core says the cooling came from cheaper petrol, and the underlying pace picked up.

If the market decides the Fed will look past the petrol, it prices fewer rate cuts. The dollar can then rise on a report that looked soft for the first few seconds.

Do not average the two into one impression. Check which measure the central bank stresses in its own words and let that one lead. When a bank has said it is watching core, a high headline driven by energy deserves much less weight. How a bank’s tone shifts that reading is in What Is Hawkish and Dovish in Forex?