What Is CPI? Consumer Price Index in Forex
CPI, the consumer price index, measures the change in prices consumers pay for a basket of goods and services. Its yearly change is the headline inflation rate, which central banks target and forex traders watch for rate moves.
CPI, the consumer price index, measures the change in prices that consumers pay for a basket of goods and services, and its change over twelve months is the headline inflation rate. Central banks set interest rates to keep that rate near their target, so every CPI release feeds straight into rate expectations.
For a trader, CPI is one of the few scheduled numbers that can move a currency pair 50 pips or more in minutes. The central banks and currencies lesson explains the rate side, and major economic releases shows the US CPI release in detail.
What do headline and core CPI mean?
Headline CPI covers all items in the basket; core CPI leaves out food and energy, whose prices swing sharply, so it shows the underlying trend. In the US September 2026 CPI report, released on 14 October 2026, headline CPI rose 3.7% over twelve months and core CPI 2.6%.
Month-on-month figures (+0.6% headline, +0.3% core that month) are what the market compares with forecasts on release day.
How do central banks react to CPI?
When inflation runs above target, a central bank tends to raise rates or hold them high; when it falls below, it tends to cut, and the currency usually moves with those expectations. Each bank sets its own goal, as the table shows.
| Central bank | Inflation goal |
|---|---|
| US Federal Reserve | 2% over the longer run |
| European Central Bank | 2% |
Most economies publish CPI every month, so each currency in a pair has its own inflation day. A pair such as EURUSD reacts to both the euro-area and the US release, and the economic calendar lists each one with its forecast and its time in UTC.
Worked example: a hot US CPI print on EURUSD
The forecast for US CPI is 3.5% over twelve months; the release shows 3.9%. Markets price in higher US rates for longer, the dollar strengthens, and EURUSD drops from 1.0850 to 1.0790. You sold 0.10 lot of EURUSD (10,000 euros), where one pip is worth $1.
| Step | Calculation | Result |
|---|---|---|
| Surprise | 3.9% − 3.5% | +0.4 percentage points |
| Move | 1.0850 − 1.0790 | 60 pips |
| Result on 0.10 lot | 60 × $1 | $60 |
Spreads can widen in the seconds around the release, so a stop placed close to the price can fill further away than set. The trading the news lesson covers how to plan entries around it.
Does high inflation always weaken a currency?
High inflation does not always weaken a currency: in the short run, a CPI print above forecast often strengthens it, because traders expect the central bank to keep rates higher. What matters on the day is the surprise against the forecast, not whether inflation is high or low.
Sources
- US Bureau of Labor Statistics (BLS), Consumer Price Index: September 2026, 14 October 2026, accessed 26 October 2026: the CPI measures the change in prices paid by consumers for goods and services; all items +0.6% m/m and +3.7% over 12 months; all items less food and energy +0.3% and +2.6%. https://www.bls.gov/news.release/cpi.nr0.htm
- Board of Governors of the Federal Reserve System, What economic goals does the Federal Reserve seek to achieve through its monetary policy?, last updated 22 August 2025, accessed 26 October 2026: maximum employment and stable prices; 2% inflation over the longer run. https://www.federalreserve.gov/faqs/what-economic-goals-does-federal-reserve-seek-to-achieve-through-monetary-policy.htm
- European Central Bank, Overview of monetary policy and markets, accessed 26 October 2026: price stability as the main aim; 2% target. https://www.ecb.europa.eu/mopo/html/index.en.html
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