headcount

Short definition from Wiktionary

Noun

1. 1
   The act of counting how many people are present in a group.
2. 2
   The number of people present in a group or employed by a company.
3. 3
   More generally, a consideration of a company's appropriate staffing level based on some larger context. (Generally used adjectivally.)
4. 4
   By extension, one slot in a workgroup, filled or to be filled by one person.