News & Analysis

What Is the Consumer Price Index (CPI)?

1 November 2022 By GO Markets


CPI is a globally recognised economic indicator used by many countries to measure inflation and assess changes in the cost of living for their citizens. It evaluates the average change over time in the prices paid by urban consumers for a market basket of consumer goods and services, such as food, clothing, rent, healthcare, entertainment, and transportation.

Compiled by national statistical agencies or organisations in various countries, the CPI reflects the purchasing power of a country’s currency. By monitoring CPI trends, policymakers and economists gain insights into the overall economic health, make informed decisions about monetary policy, and understand how price changes impact the general population’s standard of living.

In an international context, different countries might have their own versions of CPI tailored to their specific economic circumstances and consumer behaviours. However, the fundamental concept remains consistent: CPI measures the average change in prices paid by consumers, making it a crucial tool for understanding inflationary pressures and making economic comparisons across nations.

Key takeaways

CPI functions as a universal tool used by countries around the world to measure inflation and evaluate changes in the cost of living. Here are the key points in this global perspective:

  1. Global Measurement of Consumer Prices: The CPI serves as a global standard for measuring changes in the prices of goods and services consumed by households. Each country typically has its own CPI, tailored to its specific consumption patterns, demographics, and economic structure.
  2. Universal Indicator of Inflation: Internationally, the CPI is universally recognised as a crucial indicator of inflation. Central banks, policymakers, economists, and businesses in various countries closely monitor CPI trends. It helps them understand the impact of price changes on their economies and make informed decisions about monetary policies and economic strategies.
  3. Diverse Basket of Goods and Services: The CPI in different countries includes a diverse basket of goods and services that are essential to the local population. This basket is regularly updated to reflect contemporary consumption habits, ensuring that the CPI accurately represents the changing cost of living for people.
  4. Data Collection and Analysis: Countries globally conduct extensive data collection efforts to calculate their CPI. This involves collecting price data from various sources, including retail outlets, service providers, and housing markets. The data collected provides valuable insights into the purchasing power of the local currency and helps assess the economic well-being of citizens.
  5. Policy Implications: CPI data influences policy decisions not only at the national level but also in international trade and finance. It affects decisions related to interest rates, social welfare programs, and economic reforms. Moreover, it plays a significant role in international economic comparisons, enabling policymakers to assess their country’s economic performance relative to others.

Understanding the CPI

For example, the US has the Bureau of Labor Statistics (BLS) conduct extensive data collection efforts to create the CPI data, gathering approximately 80,000 price points every month from 23,000 retail and service outlets. Despite both CPI variants having the term “urban” in their names, the more comprehensive and widely referenced version covers 93% of the U.S. population.

Within the CPI, the housing category, which constitutes a significant one-third of the index, is determined through a survey of rental prices for 50,000 housing units. This data is then utilised to calculate the increase in rental prices as well as the equivalent costs for homeowners.

In particular, the owners’ equivalent category factors in the rent equivalent for owner-occupied housing, ensuring an accurate representation of housing expenses in consumer spending. It includes user fees and sales or excise taxes but excludes income taxes and the prices of investments like stocks, bonds, or life insurance policies from CPI calculations.

The calculation of CPI indexes incorporates several important considerations. Firstly, it accounts for substitution effects, recognising that consumers tend to redirect their spending when certain products or categories become relatively more expensive. Additionally, the calculation adjusts price data to accommodate changes in product quality and features, ensuring a more accurate representation of actual consumer spending.

Moreover, the weighting of product and service categories in the CPI indexes is based on recent consumer spending patterns, derived from a separate survey. This weighting reflects the significance of different items in the average consumer’s budget, providing a realistic portrayal of how expenditure is distributed across various goods and services. By integrating these factors, CPI indexes offer a nuanced and precise measurement of changes in the cost of living for consumers.

CPI Categories

The monthly CPI released by the BLS provides a comprehensive overview of economic changes. This report highlights alterations from the previous month for the overall CPI-U and its significant subcategories, including the unadjusted year-over-year changes. The BLS detailed tables further break down price shifts for a wide array of goods and services grouped under eight overarching spending categories.

These detailed tables allow for precise analysis, estimating price variations for items ranging from everyday groceries like tomatoes and salad dressing to services such as auto repairs and sporting event tickets. For each subcategory, both seasonally adjusted and unadjusted price changes are provided, offering a nuanced understanding of consumer spending patterns.

Beyond the national CPI indexes, the BLS also publishes CPI data for US regions, sub-regions, and major metropolitan areas. Notably, metropolitan data can exhibit more significant fluctuations, primarily serving the purpose of identifying localised price changes based on unique regional conditions.

What Makes CPI Significant for Currency Traders?

The CPI indicator, often termed “headline inflation” in markets, holds immense significance in the realm of currency trading. This is primarily because inflation has a profound impact on the decisions taken by central banks concerning their monetary policies.

Central banks, like the Federal Reserve and the Bank of Japan, typically have a mandate to maintain inflation at a specific level, often around 2.0% annually (source: the Fed, BOJ). To achieve these targets, policymakers adjust interest rates, employing them as a mechanism to attain the desired inflation levels. Additionally, they might implement other strategies such as bond-purchasing agreements or expanding the money supply.

When inflation levels deviate from these targets, it serves as an important signal for central banks to consider altering interest rates. If inflation exceeds the 2.0% target, central banks like the Federal Reserve might increase interest rates to curb excessive spending. This, in turn, strengthens the dollar against other currencies since a higher interest rate makes the U.S. currency more attractive.

Furthermore, CPI serves as a forward-looking indicator of an economy’s performance. In instances where inflation rises sharply, as witnessed in countries like Brazil and Venezuela in recent years, consumers tend to save less as their purchasing power diminishes. This dynamic reflects the broader economic landscape and significantly influences market behaviours and currency values.

When a central bank raises interest rates to counter inflation, it usually leads to a reduction in borrowing. Both individuals, seeking loans for purchases, and businesses, aiming to expand their operations, tend to cut back on borrowing due to the higher cost. This decrease in borrowing activity can have significant implications for a nation’s overall Gross Domestic Product (GDP).

How CPI Data Affects the Dollar on the Forex Market?

The Federal Reserve operates under a dual mandate: to achieve full employment and maintain a stable, healthy rate of inflation during economic expansion. Consequently, forex traders closely watch both unemployment and inflation data, as these figures influence the central bank’s decisions on adjusting interest rates—decisions that significantly affect currency strength or weakness.

Forex traders regard the CPI and Core CPI figures as pivotal indicators for gauging an economy’s performance. Among these, Core CPI provides a more insightful perspective by excluding volatile energy and food prices. In the United States, the Labor Department releases these figures, excluding energy and food costs from the measurement. If the Core CPI surpasses market expectations, the dollar typically strengthens against other currencies. Conversely, if these readings fall short of consensus forecasts, the currency weakens relative to other pairs.

Importantly, the impact extends beyond the monthly report. Like all government data, CPI figures are subject to revisions by economists. Such revisions can spark significant volatility in a currency’s value on the global market. This continuous assessment of economic indicators shapes traders’ strategies, highlighting the vital role of CPI data in the forex market.


CPI is a pivotal measure reflecting pricing dynamics within an economy and serves as a reliable indicator of inflation. Forex traders keenly observe the CPI because it often prompts adjustments in monetary policies by central banks. These policy changes can either bolster or diminish a currency’s value relative to its counterparts in the markets. Additionally, the strength or weakness of a currency profoundly influences the earnings of companies operating in diverse global markets, making CPI a key metric watched closely by both traders and businesses.

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