diff --git a/cctv-scheduler.py b/cctv-scheduler.py
index d23d652..c04765f 100644
--- a/cctv-scheduler.py
+++ b/cctv-scheduler.py
@@ -2,6 +2,7 @@
 # pylint: disable=C0103,C0302,C0114,W0621
 
 
+import calendar
 import base64
 import json
 import logging
@@ -2264,6 +2265,87 @@ class Do():
                         )
         return True
 
+    @staticmethod
+    def date_calc(
+        target: datetime.date = datetime.datetime.now(),
+        amount: int = 0,
+        period: str = None
+        ) -> dict:
+        """Calculating start/end dates for period: day, week, month, year.
+
+        Args:
+            target (datetime.date, optional): date in the calculation period. Defaults to now.
+            amount (int, optional): +/- periods. Defaults to 0.
+            period (str, optional): 'y'|'year','m'|'month','w'|'week','d'|'day'. Defaults to None.
+
+        Raises:
+            ValueError: 'period' value is wrong.
+
+        Returns:
+            dict: {
+                'start':{'y':int,'m':int,'w':int,'d':int},
+                'end':{'y':int,'m':int,'w':int,'d':int}
+                }.
+        """
+        if Do.args_valid(locals(), Do.date_calc.__annotations__):
+            date = {}
+            if not period:
+                raise ValueError("'period' value is wrong: " + "''")
+            elif period == 'd' or period == 'day':
+                delta = target + datetime.timedelta(days=amount)
+                target = delta
+                date['period'] = 'day'
+            elif period == 'w' or period == 'week':
+                delta = target + datetime.timedelta(weeks=amount)
+                target_week = str(delta.year) + '-W' + str(delta.isocalendar()[1])
+                target = datetime.datetime.strptime(target_week + '-1', "%G-W%V-%u")
+                delta = target + datetime.timedelta(days=6)
+                date['period'] = 'week'
+            elif period == 'm' or period == 'month':
+                delta_month = (target.month + amount) % 12
+                if not delta_month:
+                    delta_month = 12
+                delta_year = target.year + ((target.month) + amount - 1) // 12
+                delta_days = calendar.monthrange(delta_year, delta_month)[1]
+                delta = target = target.replace(
+                    year=delta_year,
+                    month=delta_month,
+                    day=1
+                )
+                delta = delta.replace(
+                    year=delta_year,
+                    month=delta_month,
+                    day=delta_days
+                )
+                date['period'] = 'month'
+            elif period == 'y' or period == 'year':
+                target = target.replace(
+                    year=target.year + amount,
+                    month=1,
+                    day=1
+                )
+                delta = target.replace(
+                    year=target.year,
+                    month=12,
+                    day=31
+                )
+                date['period'] = 'year'
+            else:
+                raise ValueError("'period' value is wrong: " + period)
+            date['start'] = {
+                'y': target.year,
+                'm': target.month,
+                'w': target.isocalendar()[1],
+                'd': target.day
+            }
+            date['end'] = {
+                'y': delta.year,
+                'm': delta.month,
+                'w': delta.isocalendar()[1],
+                'd': delta.day
+            }
+            return date
+
 
 if __name__ == "__main__":
     time_start = datetime.now()