What Is the Purchasing Managers’ Index?

The Purchasing Managers’ Index (PMI) is a monthly economic indicator that reflects the prevailing direction of economic trends in the manufacturing and service sectors. It is based on surveys of purchasing managers at private-sector companies and is used to provide insight into business conditions, including output, new orders, employment, supplier delivery times, and inventories. The PMI is widely regarded as a leading indicator of economic activity, helping analysts, investors, policymakers, and business leaders anticipate shifts in growth momentum.

The most prominent PMIs are published by the Institute for Supply Management (ISM) in the United States and S&P Global (formerly IHS Markit) globally. Each PMI is calculated based on a diffusion index, summarizing whether market conditions—as reported by purchasing managers—are improving, staying the same, or worsening.

Structure and Methodology

The PMI is constructed using a standardized set of survey questions sent to purchasing and supply executives. Respondents are asked to indicate whether various business conditions have improved, remained unchanged, or deteriorated compared to the previous month. The questions cover key areas such as:

• New orders
• Production/output
• Employment
• Supplier deliveries
• Inventories (primarily for manufacturing PMIs)

Each response is weighted and translated into a numerical index. For each category, the percentage of respondents reporting improvement is added to half the percentage reporting no change. This results in a diffusion index ranging from 0 to 100. The final PMI figure is a composite index, typically giving equal weight to each component, though some PMIs may assign different weights depending on the sector.

A PMI above 50 generally indicates expansion compared to the previous month, while a reading below 50 signals contraction. A reading of exactly 50 suggests no change.

Types of PMIs

There are several types of PMIs, each focused on a specific sector:

• Manufacturing PMI: Measures activity in the goods-producing sector. It includes data on factory orders, production volumes, employment trends, and supplier performance.
• Services PMI (or Non-Manufacturing PMI): Focuses on the service sector, including business activity, incoming new work, employment, and input prices.
• Composite PMI: A combination of the manufacturing and services PMIs, weighted by each sector’s contribution to GDP. This provides a broader view of overall private-sector business conditions.

The U.S. ISM publishes separate PMIs for manufacturing and services, while S&P Global produces both individual and composite PMIs for numerous countries and regions.

Economic Significance

PMIs are considered leading indicators because they tend to move ahead of broader economic measures such as GDP. Purchasing managers are often among the first to sense changes in market demand, supply chain constraints, cost pressures, or labor market shifts. Because of this early insight, PMI data is often used to forecast economic turning points.

For example, a rising PMI over several months may suggest accelerating growth and encourage a more optimistic economic outlook. In contrast, a consistently declining PMI may signal a slowdown or recession, prompting caution from investors and policymakers.

Central banks and government agencies may use PMI data to help guide monetary and fiscal policy decisions. Financial markets also react to PMI releases, especially if the data deviates significantly from expectations.

Global Comparisons and Benchmarks

S&P Global publishes PMIs for dozens of economies, enabling cross-country comparisons of business conditions. These global PMIs are especially important for multinational companies and investors who need to track regional or global trends.

The Eurozone, China, the United Kingdom, and Japan are among the regions with widely watched PMIs. China's official PMI is published by the National Bureau of Statistics, while the Caixin PMI offers an alternative view, focusing more on smaller and private-sector firms.

PMIs also contribute to composite indicators like the J.P. Morgan Global Composite PMI, which aggregates data from several countries to provide a worldwide snapshot of economic momentum.

Limitations and Considerations

While PMI data is timely and forward-looking, it has limitations. The index is based on subjective perceptions of business conditions and is not a direct measurement of output or employment. Seasonal adjustments and changes in response rates can also affect reliability.

In addition, since PMIs are relative month-to-month comparisons, they may not reflect the full scale of long-term changes in output or labor market health. A reading above 50 indicates growth relative to the prior month but does not specify the magnitude of that growth.

PMIs can also be influenced by temporary shocks, such as weather disruptions, labor strikes, or supply chain bottlenecks. Therefore, PMI trends are generally more reliable when observed over multiple months rather than relying on a single release.

The Bottom Line

The Purchasing Managers’ Index (PMI) is a vital economic tool used to gauge business activity and sentiment in both manufacturing and services. Its forward-looking nature, based on real-time survey data, makes it an essential resource for anticipating economic shifts. While it should be interpreted in context and not as a standalone indicator, the PMI remains one of the most widely used signals for assessing economic momentum in the short term.