What Is Industrial Production Index?

The industrial production index (IPI) is a monthly economic indicator measuring real output in the manufacturing, mining, electric and gas industries, relative to a base year. It is reported on by the Conference Board.

How Does the Industrial Production Index (IPI) Work?

The Federal Reserve Board (FRB) publishes the industrial production index (IPI) in the middle of every month, and revisions to previous estimates are released at the end of every March. The IPI measures levels of production by the manufacturing sector, mining – including oil and gas field drilling services – and electrical and gas utilities. It also measures capacity, an estimate of the production levels that could be sustainably maintained; and capacity utilization, the ratio of actual output to capacity.

Calculating IPI

Industrial production and capacity levels are expressed as an index level relative to a base year (currently 2012). In other words, they do not express absolute production volumes or values, but the percentage change in production relative to 2012. The source data is varied, including physical inputs and outputs such as tons of steel; inflation-adjusted sales figures; and, when other these other data sources are not available, hours logged by production workers. The FRB obtains these data from industry associations and government agencies and aggregates them into an index using the Fisher-ideal formula.

Within the overall IPI there are a number of sub-indices providing a detailed look at the output of highly specific industries: residential gas sales, ice cream and frozen dessert, carpet and rug mills, spring and wire product, pig iron, audio and video equipment, and paper are just a few of the dozens of industries for which monthly production data is available.

The indices are available in seasonally adjusted and unadjusted formats.

Interpreting IPI

Industry-level data are useful for managers and investors within specific lines of business, while the composite index is an important macroeconomic indicator for economists and investors. Fluctuations within the industrial sector account for most of the variation in overall economic growth, so a monthly metric helps keep investors apprised of shifts in output. At the same time, IPI differs from the most popular measure of economic output, gross domestic product (GDP): GDP measures the price paid by the end-user, so it includes value-added in the retail sector, which IPI ignores. It is also important to note that the industrial sector makes up a low and falling share of the U.S. economy: less than 20% of GDP as of 2016. 

Capacity utilization is a useful indicator of the strength of demand. Low capacity utilization – overcapacity, in other words – signals weak demand. Policymakers could read it as a signal that fiscal or monetary stimulus is needed. Investors could read it as a sign of a coming downturn, or – depending on the signals from Washington – as a sign of coming stimulus. High capacity utilization, on the other hand, can act as a warning that the economy is overheating, suggesting the risk of price rises and asset bubbles. Policymakers could react to those threats with interest rate rises or fiscal austerity, or they could let the business cycle take its course, likely resulting in a recession eventually.

Historical Data

Below is the seasonally-adjusted industrial production index for the 50 years to October 2017. Data is available going back to January 1919.