What is the employment diffusion index?

The employment diffusion index, published by the Bureau of Labor Statistics as part of the monthly jobs report, measures the percentage of industries that are expanding employment over a given period. It provides a measure of the breadth of job creation across the economy. A reading of 50 means exactly half of industries are adding jobs and half are cutting. Readings above 50 indicate broad-based hiring; readings below 50 signal widespread job losses.

Breadth matters because aggregate job numbers can mask important dynamics. An economy might add 200,000 jobs in a month, but if all the gains are concentrated in a single sector (like government or healthcare) while many other industries are shrinking, the labor market is less healthy than the headline suggests. The diffusion index captures this by weighting every industry equally. During healthy expansions, the index typically reads 55-65, meaning a solid majority of industries are hiring. Before recessions, the index drops below 50, often months before aggregate job losses become apparent.

The BLS calculates diffusion indexes at various time horizons, including one-month, three-month, six-month, and twelve-month changes. The longer-period indexes smooth out monthly volatility and provide a clearer trend signal. The 6-month diffusion index is particularly popular among business cycle analysts because a sustained decline from the 60s to the low 50s or below has historically preceded NBER-dated recession starts with reasonable lead time.

For investors, the diffusion index offers an early warning system that complements headline payroll numbers. When the index begins declining while total jobs are still growing, it suggests that hiring is narrowing to fewer sectors and the expansion may be maturing. This pattern was visible before the 2001, 2008, and 2020 recessions. Monitoring the breadth of employment alongside its level provides a more complete picture of labor market conditions and a better foundation for anticipating turning points in the business cycle.