Specifically, you are looking for various measures of "not in the labor force" -- called U1 through U6.

https://www.bls.gov/news.release/empsit.t15.htm

U6 is: Total unemployed, plus all persons marginally attached to the labor force, plus total employed part time for economic reasons, as a percent of the civilian labor force plus all persons marginally attached to the labor force

The national U6 right now is 9.2 (unadjusted).