diff --git a/library/src/calculator_functions.cpp b/library/src/calculator_functions.cpp
index fb096d3..bbfe323 100644
--- a/library/src/calculator_functions.cpp
+++ b/library/src/calculator_functions.cpp
@@ -444,6 +444,35 @@ bool Calculator::checkDurationMinutes(bool overtime,
     return true;
 }
 
+int Calculator::findWorkTimeRange(QDateTime const &dt,
+                                  QScopedArrayPointer<TariffTimeRange> const &worktime,
+                                  size_t size) {
+    for (size_t w = 0; w < size; ++w) {
+        QTime const &worktime_from = worktime[w].getTimeFrom();
+        QTime const &worktime_to = worktime[w].getTimeUntil();
+
+        if ((dt.time() >= worktime_from) && (dt.time() < worktime_to)) {
+            return w;
+        }
+    }
+    return -1;
+}
+
+int Calculator::findNextWorkTimeRange(QDateTime const &dt,
+                                         QScopedArrayPointer<TariffTimeRange> const &worktime,
+                                         size_t size) {
+    int nextWorkTimeRange = -1;
+    for (size_t w = 0; w < size; ++w) {
+        QTime const &worktime_from = worktime[w].getTimeFrom();
+
+        if (dt.time() < worktime_from) {
+            nextWorkTimeRange = w;
+            continue;
+        }
+    }
+    return nextWorkTimeRange;
+}
+
 using namespace Utilities;
 
 uint32_t Calculator::private_GetCostFromDuration(Configuration const* cfg,