1 files changed, 6 insertions, 1 deletions
diff --git a/src/IOL.Helpers/DateTimeHelpers.cs b/src/IOL.Helpers/DateTimeHelpers.cs
index 07e951e..98b3ee9 100644
--- a/src/IOL.Helpers/DateTimeHelpers.cs
+++ b/src/IOL.Helpers/DateTimeHelpers.cs
@@ -18,5 +18,10 @@ namespace IOL.Helpers
 		}
 
 		public static DateTime ToOsloTimeZone(this DateTime value) => ToTimeZoneId(value, "Europe/Oslo");
+
+		public static DateTime StartOfWeek(this DateTime dt, DayOfWeek startOfWeek) {
+			var diff = (7 + (dt.DayOfWeek - startOfWeek)) % 7;
+			return dt.AddDays(-1 * diff).Date;
+		}
 	}
-}
-\ No newline at end of file
+}