Time Sheet Calculator Calculate Hours allows you to enter times worked, like: 7:45, 11, 12:10, 3, 4, 4:30 and it will add up the time worked into a meaningful hour:minute format. Also see our mobile time card calculator app. This calculator can be used by individuals adding up their own weekly work hours and time sheets and also payroll departments processing multiple employees. Companies can also direct their employees to our site to settle and print weekly time reports to assist in company payroll activities.