diff --git a/app.py b/app.py
index 226d9e8..31ee42c 100644
--- a/app.py
+++ b/app.py
@@ -15,6 +15,7 @@ from dotenv import load_dotenv
 from logger_handler import AppLogger, log_user_activity, log_database_operations
 
 from single_checkin_calculator import SingleCheckInCalculator
+from working_hours_calculator import WorkingHoursCalculator
 from payroll_excel_exporter import PayrollExcelExporter
 from enhanced_payroll_excel_exporter import EnhancedPayrollExcelExporter
 from time_attendance_import_service import TimeAttendanceImportService
@@ -5265,7 +5266,7 @@ def payroll_dashboard():
 
                 # Calculate working hours if we have records
                 if attendance_records:
-                    calculator = SingleCheckInCalculator()
+                    calculator = WorkingHoursCalculator()
                     working_hours_data = calculator.calculate_all_employees_hours(
                         start_date, end_date, attendance_records
                     )
@@ -7417,7 +7418,7 @@ def export_time_attendance_excel(records, project_name_for_filename, date_range_
         converted_records.append(converted_record)
     
     # Calculate working hours using SingleCheckInCalculator
-    calculator = SingleCheckInCalculator()
+    calculator = WorkingHoursCalculator()
     hours_data = calculator.calculate_all_employees_hours(
         datetime.combine(start_date, datetime.min.time()),
         datetime.combine(end_date, datetime.max.time()),
diff --git a/enhanced_payroll_excel_exporter.py b/enhanced_payroll_excel_exporter.py
index 4b3863a..204a3bd 100644
--- a/enhanced_payroll_excel_exporter.py
+++ b/enhanced_payroll_excel_exporter.py
@@ -12,7 +12,7 @@ from typing import List, Dict, Optional, Any
 from openpyxl import Workbook
 from openpyxl.styles import Font, PatternFill, Alignment, Border, Side
 from openpyxl.utils import get_column_letter
-from single_checkin_calculator import SingleCheckInCalculator
+from working_hours_calculator import WorkingHoursCalculator
 from logger_handler import log_database_operations
 
 
@@ -93,7 +93,7 @@ class EnhancedPayrollExcelExporter:
                 employee_names = self._get_employee_names(attendance_records)
             
             # Calculate working hours using enhanced calculator
-            calculator = SingleCheckInCalculator()
+            calculator = WorkingHoursCalculator()
             working_hours_data = calculator.calculate_all_employees_hours(
                 start_date, end_date, attendance_records
             )
@@ -294,7 +294,7 @@ class EnhancedPayrollExcelExporter:
                 employee_names = self._get_employee_names(attendance_records)
             
             # Calculate working hours
-            calculator = SingleCheckInCalculator()
+            calculator = WorkingHoursCalculator()
             working_hours_data = calculator.calculate_all_employees_hours(
                 start_date, end_date, attendance_records
             )
diff --git a/payroll_excel_exporter.py b/payroll_excel_exporter.py
index 4dc8679..98bc186 100644
--- a/payroll_excel_exporter.py
+++ b/payroll_excel_exporter.py
@@ -20,7 +20,7 @@ from typing import List, Dict, Any, Optional
 from openpyxl import Workbook
 from openpyxl.styles import Font, Alignment, PatternFill, Border, Side
 from openpyxl.utils import get_column_letter
-from single_checkin_calculator import SingleCheckInCalculator
+from working_hours_calculator import WorkingHoursCalculator
 from logger_handler import log_database_operations
 
 
@@ -181,7 +181,7 @@ class PayrollExcelExporter:
                 employee_names = self._get_employee_names(attendance_records)
             
             # Calculate working hours
-            calculator = SingleCheckInCalculator()
+            calculator = WorkingHoursCalculator()
             hours_data = calculator.calculate_all_employees_hours(start_date, end_date, attendance_records)
             
             # Create workbook
@@ -417,7 +417,7 @@ class PayrollExcelExporter:
                 employee_names = self._get_employee_names(attendance_records)
             
             # Calculate working hours
-            calculator = SingleCheckInCalculator()
+            calculator = WorkingHoursCalculator()
             hours_data = calculator.calculate_all_employees_hours(start_date, end_date, attendance_records)
             
             # Create workbook
@@ -544,7 +544,7 @@ class PayrollExcelExporter:
                 employee_names = self._get_employee_names(attendance_records)
             
             # Calculate working hours
-            calculator = SingleCheckInCalculator()
+            calculator = WorkingHoursCalculator()
             hours_data = calculator.calculate_all_employees_hours(start_date, end_date, attendance_records)
             
             # Create workbook with single sheet