Core Inflation

Core inflation excludes the most volatile components of the Consumer Price Index — food and energy — to reveal the underlying inflation trend. Policymakers, especially the Federal Reserve, focus on core inflation because headline inflation can be distorted by temporary commodity shocks that are not driven by demand-side pressures.

Why exclude food and energy

Food and energy prices are volatile and often driven by supply shocks unrelated to monetary policy or demand:

• Oil spikes due to geopolitical events (OPEC cuts, war in Middle East) — not directly related to US economic strength.
• Crop failures (drought in Ukraine, floods in India) → food prices spike — again, a supply shock, not demand.
• Weather patterns (warm winter lowers heating costs, hot summer lowers AC costs) cause monthly swings.

These shocks pass through to inflation quickly but often reverse just as quickly. A policymaker raising rates because oil spiked might be overreacting if the spike is temporary.

Core inflation and monetary policy

The Federal Reserve uses core inflation to distinguish:

Temporary shocks → leave monetary policy alone

• Oil spikes from supply disruption.
• Food prices spike from poor harvest.
• These tend to reverse, and tightening is counterproductive.

Persistent demand pressure → tighten policy

• Demand outstrips supply consistently.
• Wage growth accelerates.
• Pricing power spreads across goods and services.
• This requires higher interest rates to slow demand.

By focusing on core, the Fed avoids overreacting to temporary commodity shocks.

Food and energy vs. other “volatile” items

Some critics argue the food/energy exclusion is too narrow. Other items are also volatile:

• Airfares — highly cyclical with fuel and demand.
• Used car prices — spiked 40%+ in 2021-22, then crashed.
• Rent — less volatile but still fluctuates with housing demand.

Alternative measures like trimmed-mean CPI exclude the top and bottom 10% of price movements each month, capturing more nuance.

Core inflation trends post-2008

• 2010-2019: Core inflation was typically 1.5–2%, below the Fed’s 2% target.
• 2020: Core inflation fell to 1.2–1.5% (demand-side weakness post-COVID).
• 2021: Core inflation rose from 1.5% to 3.5% as demand rebounded and supply lagged.
• 2022: Core inflation peaked at 6.6% as wage growth accelerated.
• 2023: Core inflation moderated toward 3% as Fed tightened.
• 2024-26: Core inflation slowly declining toward 2% target.

Core versus headline: examples

2022 Oil spike:

• Headline inflation peaked at 9.1% (June 2022) due to energy.
• Core inflation peaked at 6.6% (Sept 2022) — still high, but less dramatic.
• The 2.5-point difference reflected the oil spike.

Late 2023 stabilization:

• Oil prices stabilized; headline inflation fell below core.
• Core stayed elevated due to sticky services inflation (rent, healthcare).
• This indicated supply-side healing but persistent demand-side pressures.

Sticky prices and core inflation

Core inflation is dominated by “sticky prices” — rents, healthcare, insurance — items that do not adjust instantly when demand changes:

• Rent adjusts annually; inflation in rents lags demand changes by 6–12 months.
• Healthcare prices are negotiated; wage-driven inflation takes time to pass through.
• Insurance premiums adjust at renewal.

Because these are sticky, core inflation is more persistent than headline inflation. It is harder to cool via tightening because the stickiness delays the adjustment.

Relationship to sticky-price CPI

A more sophisticated measure is sticky-price CPI, which tracks only items with infrequent price changes:

• Sticky-price CPI is often 0.5–1 point higher than core inflation.
• It turns faster than core inflation in response to demand shocks.
• Some economists argue it is a better leading indicator of future core inflation.

The Federal Reserve monitors multiple measures — core CPI, core PCE, sticky-price CPI, trimmed-mean CPI — to triangulate true underlying inflation.

See also