diff --git a/src/helper.cpp b/src/helper.cpp
index ea74a1ae..5473038e 100644
--- a/src/helper.cpp
+++ b/src/helper.cpp
@@ -458,3 +458,24 @@ std::vector <Daterange> subtractRanges (
 }
 
 ////////////////////////////////////////////////////////////////////////////////
+Daterange overallRangeFromIntervals (const std::vector <Interval>& intervals)
+{
+  Daterange overall;
+
+  for (auto& interval : intervals)
+  {
+    if (interval.start () < overall.start () || overall.start ().toEpoch () == 0)
+      overall.start (interval.start ());
+
+    // Deliberately mixed start/end.
+    if (interval.start () > overall.end ())
+      overall.end (interval.start ());
+
+    if (interval.end () > overall.end ())
+      overall.end (interval.end ());
+  }
+
+  return overall;
+}
+
+////////////////////////////////////////////////////////////////////////////////
diff --git a/src/timew.h b/src/timew.h
index 829f5162..36b1496f 100644
--- a/src/timew.h
+++ b/src/timew.h
@@ -57,6 +57,7 @@ std::string jsonFromIntervals (const std::vector <Interval>&);
 std::vector <Daterange> rangesFromHolidays (const Rules&);
 std::vector <Daterange> addRanges (const Daterange&, const std::vector <Daterange>&, const std::vector <Daterange>&);
 std::vector <Daterange> subtractRanges (const Daterange&, const std::vector <Daterange>&, const std::vector <Daterange>&);
+Daterange overallRangeFromIntervals (const std::vector <Interval>&);
 
 // utiŀ.cpp
 std::string osName ();