What is Core CPI?
Core CPI measures the same basket of consumer goods and services as headline CPI, but leaves out food and energy. Those two categories can swing sharply from month to month because of weather, harvests or oil prices — moves that often say little about the broader inflation trend.
What remains — housing and rents, services, cars, clothing, medical care and more — tends to change more slowly and more persistently. As with CPI, markets focus on the month-over-month change (m/m).
Why markets pay attention
Central banks try to look past temporary price swings and respond to lasting inflation. Core CPI is closer to that lasting component, so a surprise in core can shift expectations for Federal Reserve policy more than a headline surprise driven by energy alone.
Core CPI and headline CPI
Both numbers arrive at the same moment, so the market reads them together:
- Headline and core both above the Forecast → a broad inflation signal.
- Headline above, core in line → the surprise probably came from food or energy and may carry less weight.
- Headline in line, core above → underlying inflation may be firmer than the headline suggests.
Actual, Forecast and Previous
Every release on an economic calendar comes with three numbers:
- Actual
- The result just published. Nobody knows it until the release.
- Forecast
- The consensus of economists, known in advance — what the market largely expects and has already priced in.
- Previous
- The result for the prior period (sometimes revised). Useful context, but not what markets mainly react to.
Surprise = Actual − Forecast
The key point: markets react mainly to how far the Actual lands from the Forecast — the surprise — not to the change from the Previous value.
Actual > Forecast
Higher than expected.
Actual ≈ Forecast
About as expected — usually the smallest reaction.
Actual < Forecast
Lower than expected.
None of these comparisons decides the EUR/USD direction on its own. Whether "higher" is good or bad news depends on the indicator (more jobs usually reads as strength, more jobless claims as weakness), on the size of the surprise and on the market context.
How a Core CPI surprise is usually read
An Actual above the Forecast points to firmer underlying inflation. Historically, that has more often supported the U.S. dollar — for EUR/USD, usually a move lower. An Actual below the Forecast has more often had the opposite effect.
Core CPI m/m is usually published to one decimal place and moves slowly, so a 0.1 percentage-point surprise is often significant. Rounding matters too: 0.34% and 0.26% can both be published as 0.3%.
A simple example
Hypothetical numbers: Previous 0.3%, Forecast 0.3%, Actual 0.4%. The surprise is +0.1 percentage points — small in size, but for a slow-moving measure it can be read as a meaningful sign that underlying inflation is not cooling as hoped.
If headline CPI in the same release came in below its Forecast because energy prices fell, the two signals partly cancel out — and the market has to decide which one matters more that day.
Why the same number can move markets differently
The size of the surprise matters
A result slightly off the Forecast may barely register, while a big miss can force a real rethink. Larger surprises have tended to produce larger and more consistent reactions — but not always.
Context changes over time
When inflation is the market's main worry, inflation data dominates; when growth is the worry, jobs and activity data can matter more. What the market already expects from the Federal Reserve also shapes how a surprise is read.
Details and revisions
Headlines come with details — revisions to earlier months, sub-components, other figures released at the same moment. They can confirm the headline or contradict it.
The first reaction is not the final one
The first move reflects the headline in the first seconds. As participants read the details, the market can extend that move, stall or reverse within minutes.
History is a guide, not a guarantee
Past releases show how markets have tended to react, which is useful. But every release happens in a new context, and past behavior does not guarantee the next reaction.
How to read EUR/USD
EUR/USD shows how many U.S. dollars one euro buys, so it tends to move opposite to the dollar: when the dollar strengthens, EUR/USD usually falls, and when it weakens, EUR/USD usually rises. Pairs where the dollar comes first, such as USD/JPY, tend to move with the dollar.
How NEXTMarketReaction reads this release
When a Core CPI release is published, NEXTMarketReaction combines:
- the Actual, as soon as it is published;
- the Forecast (consensus) and the Previous value;
- the surprise — how far, and in which direction, the Actual landed from the Forecast;
- how EUR/USD has behaved after comparable Core CPI releases in the past;
- calibrated historical probabilities, adjusted so that the percentages reflect how often similar situations actually played out;
- the horizon: 1, 3, 5, 8 or 15 minutes after the release.
The UP/DOWN percentage you see is a probability estimate based on history and a statistical model — not a certainty and not a recommendation. Even a high percentage leaves the opposite outcome possible.