diff --git a/homeassistant/components/calendar/caldav.py b/homeassistant/components/calendar/caldav.py
index ba798ce7902..d70e7ff8946 100644
--- a/homeassistant/components/calendar/caldav.py
+++ b/homeassistant/components/calendar/caldav.py
@@ -166,7 +166,7 @@ class WebDavCalendarData(object):
         self.event = {
             "summary": vevent.summary.value,
             "start": self.get_hass_date(vevent.dtstart.value),
-            "end": self.get_hass_date(vevent.dtend.value),
+            "end": self.get_hass_date(self.get_end_date(vevent)),
             "location": self.get_attr_value(vevent, "location"),
             "description": self.get_attr_value(vevent, "description")
         }
@@ -194,7 +194,7 @@ class WebDavCalendarData(object):
     @staticmethod
     def is_over(vevent):
         """Return if the event is over."""
-        return dt.now() > WebDavCalendarData.to_datetime(vevent.dtend.value)
+        return dt.now() > WebDavCalendarData.get_end_date(vevent)
 
     @staticmethod
     def get_hass_date(obj):
@@ -217,3 +217,17 @@ class WebDavCalendarData(object):
         if hasattr(obj, attribute):
             return getattr(obj, attribute).value
         return None
+
+    @staticmethod
+    def get_end_date(obj):
+        """Return the end datetime as determined by dtend or duration."""
+        if hasattr(obj, "dtend"):
+            enddate = obj.dtend.value
+
+        elif hasattr(obj, "duration"):
+            enddate = obj.dtstart.value + obj.duration.value
+
+        else:
+            enddate = obj.dtstart.value + timedelta(days=1)
+
+        return WebDavCalendarData.to_datetime(enddate)
diff --git a/tests/components/calendar/test_caldav.py b/tests/components/calendar/test_caldav.py
index 7234d40c410..e44e5cfc1f0 100644
--- a/tests/components/calendar/test_caldav.py
+++ b/tests/components/calendar/test_caldav.py
@@ -64,7 +64,49 @@ LOCATION:Hamburg
 DESCRIPTION:What a beautiful day
 END:VEVENT
 END:VCALENDAR
+""",
+    """BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:-//Global Corp.//CalDAV Client//EN
+BEGIN:VEVENT
+UID:4
+DTSTAMP:20171125T000000Z
+DTSTART:20171127
+SUMMARY:This is an event without dtend or duration
+LOCATION:Hamburg
+DESCRIPTION:What an endless day
+END:VEVENT
+END:VCALENDAR
+""",
+    """BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:-//Global Corp.//CalDAV Client//EN
+BEGIN:VEVENT
+UID:5
+DTSTAMP:20171125T000000Z
+DTSTART:20171127
+DURATION:PT1H
+SUMMARY:This is an event with duration
+LOCATION:Hamburg
+DESCRIPTION:What a day
+END:VEVENT
+END:VCALENDAR
+""",
+    """BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:-//Global Corp.//CalDAV Client//EN
+BEGIN:VEVENT
+UID:6
+DTSTAMP:20171125T000000Z
+DTSTART:20171127T100000Z
+DURATION:PT1H
+SUMMARY:This is an event with duration
+LOCATION:Hamburg
+DESCRIPTION:What a day
+END:VEVENT
+END:VCALENDAR
 """
+
 ]