US Department of Labor:
At the Department of Labor we regularly get questions about what the “real” unemployment rate is. Another way to state these questions might be “What is the measure that truly captures the state of job opportunities?” The answer, it turns out, is there isn’t just one. There is no way to capture the state of something as complex as the U.S. labor market with one number. That is why the department’s Bureau of Labor Statistics publishes a huge array of measures, which together provide a comprehensive picture of the state of job opportunities.
The “official” unemployment rate is the most well-known. BLS defines a worker as unemployed if they are jobless but actively seeking work. The official unemployment rate is the number of workers who are unemployed divided by the number of workers who are either employed or unemployed. At its peak in the aftermath of the Great Recession, the official unemployment rate reached 10 percent; as of August 2016, it is now down to 4.9.
In BLS publications, the official unemployment rate is referred to as the U-3. Though the U-3 gets the most attention, BLS also publishes five other measures of labor underutilization (U-1, U-2, U-4, U-5, and U-6), each of which measure labor underutilization in a different way. The broadest measure – the U-6 (sometimes referred to in the press as the “underemployment rate”) – includes not just the officially unemployed, but also the “marginally attached” (those who are neither working nor looking for work but who want and are available to work and have looked for work in the past year), and people who are working part-time but want a full-time job. At its peak in the aftermath of the Great Recession, the U-6 was 17.1 percent; it is now down to 9.7 percent.