diff --git a/calendar/inc/class.calendar_uiforms.inc.php b/calendar/inc/class.calendar_uiforms.inc.php
index 5b21e99084..3497142461 100644
--- a/calendar/inc/class.calendar_uiforms.inc.php
+++ b/calendar/inc/class.calendar_uiforms.inc.php
@@ -359,6 +359,11 @@ class calendar_uiforms extends calendar_ui
 				unset($content['alarm'][$id]);
 			}
 		}
+		if($content['end'] && $content['start'] >= $content['end'])
+		{
+			unset($content['end']);
+			$content['duration'] = $this->bo->cal_prefs['defaultlength']*60;
+		}
 		if ($content['duration'])
 		{
 			$content['end'] = $content['start'] + $content['duration'];
diff --git a/calendar/js/app.js b/calendar/js/app.js
index 9c061cee86..e4b2d527cb 100644
--- a/calendar/js/app.js
+++ b/calendar/js/app.js
@@ -1287,6 +1287,14 @@ var CalendarApp = /** @class */ (function (_super) {
             if (recur_end && recur_end.getValue && !recur_end.getValue()) {
                 recur_end.set_min(widget.getValue());
             }
+            // Update end date, min duration is 1 minute
+            var end = widget.getRoot().getDOMWidgetById('end');
+            var start_time = new Date(widget.getValue());
+            var end_time = new Date(end.getValue());
+            if (end_time <= start_time) {
+                start_time.setMinutes(start_time.getMinutes() + 1);
+                end.set_value(start_time);
+            }
         }
         // Update currently selected alarm time
         this.alarm_custom_date();
diff --git a/calendar/js/app.ts b/calendar/js/app.ts
index 504693c396..cd143b6592 100644
--- a/calendar/js/app.ts
+++ b/calendar/js/app.ts
@@ -1347,9 +1347,20 @@ class CalendarApp extends EgwApp
 			{
 				recur_end.set_min(widget.getValue());
 			}
+
+			// Update end date, min duration is 1 minute
+			let end = <et2_date> widget.getRoot().getDOMWidgetById('end');
+			let start_time = new Date(widget.getValue());
+			let end_time = new Date(end.getValue());
+			if(end_time <= start_time)
+			{
+				start_time.setMinutes(start_time.getMinutes() + 1);
+				end.set_value(start_time);
+			}
 		}
 		// Update currently selected alarm time
 		this.alarm_custom_date();
+
 	}
 
 	/**