How are the 1,250 hours worked calculated for FMLA eligibility?

Agencies must count all hours actually worked, including overtime.
Employees returning from military service (USERRA) also receive credit for the hours they would have worked if not for their military duty.
Example:
If an employee worked 37.5 hours per week and served 20 weeks of military duty, the hours that would have been worked (20 × 37.5 = 750 hours) are added to the actual hours worked during the 12 months before leave.
For more information, visit the State of Tennessee Attendance and Leave Manual.