diff --git a/navalplanner-webapp/src/main/java/org/navalplanner/web/montecarlo/MonteCarloController.java b/navalplanner-webapp/src/main/java/org/navalplanner/web/montecarlo/MonteCarloController.java
index 8b2a94261..648643eae 100644
--- a/navalplanner-webapp/src/main/java/org/navalplanner/web/montecarlo/MonteCarloController.java
+++ b/navalplanner-webapp/src/main/java/org/navalplanner/web/montecarlo/MonteCarloController.java
@@ -43,6 +43,7 @@ import org.zkoss.zk.ui.event.EventListener;
 import org.zkoss.zk.ui.event.Events;
 import org.zkoss.zk.ui.util.GenericForwardComposer;
 import org.zkoss.zul.Button;
+import org.zkoss.zul.Checkbox;
 import org.zkoss.zul.Decimalbox;
 import org.zkoss.zul.Grid;
 import org.zkoss.zul.Intbox;
@@ -78,6 +79,8 @@ public class MonteCarloController extends GenericForwardComposer {
 
     private Button btnRunMonteCarlo;
 
+    private Checkbox cbGroupByWeeks;
+
     private Window monteCarloChartWindow;
 
     public MonteCarloController() {
@@ -157,8 +160,10 @@ public class MonteCarloController extends GenericForwardComposer {
                         "/planner/montecarlo_function.zul", self, args);
                 MonteCarloGraphController controller = (MonteCarloGraphController) result
                         .getVariable("monteCarloGraphController", true);
+
                 final String orderName = monteCarloModel.getOrderName();
-                controller.generateMonteCarloGraph(orderName, data);
+                final boolean groupByWeeks = cbGroupByWeeks.isChecked();
+                controller.generateMonteCarloGraph(orderName, data, groupByWeeks);
 
                 return result;
             }
diff --git a/navalplanner-webapp/src/main/java/org/navalplanner/web/montecarlo/MonteCarloGraphController.java b/navalplanner-webapp/src/main/java/org/navalplanner/web/montecarlo/MonteCarloGraphController.java
index 23dfee694..fe1258240 100644
--- a/navalplanner-webapp/src/main/java/org/navalplanner/web/montecarlo/MonteCarloGraphController.java
+++ b/navalplanner-webapp/src/main/java/org/navalplanner/web/montecarlo/MonteCarloGraphController.java
@@ -3,11 +3,9 @@ package org.navalplanner.web.montecarlo;
 import java.math.BigDecimal;
 import java.util.ArrayList;
 import java.util.Collections;
-import java.util.Comparator;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
-import java.util.Set;
 
 import org.joda.time.LocalDate;
 import org.springframework.beans.factory.config.BeanDefinition;
@@ -47,16 +45,58 @@ public class MonteCarloGraphController extends GenericForwardComposer {
         self.setVisible(false);
     }
 
-    public void generateMonteCarloGraph(String orderName, Map<LocalDate, BigDecimal> data) {
-        CategoryModel xymodel = new SimpleCategoryModel();
-
-        List<LocalDate> dates = new ArrayList(data.keySet());
-        Collections.sort(dates);
-        for (LocalDate each: dates) {
-            String labelDate = each.toString();
-            xymodel.setValue(orderName, labelDate, data.get(each));
+    public void generateMonteCarloGraph(String orderName, Map<LocalDate, BigDecimal> data, boolean byWeek) {
+        CategoryModel xymodel;
+        if (byWeek) {
+            xymodel = generateMonteCarloGraphByWeek(orderName, groupByWeek(data));
+        } else {
+            xymodel = generateMonteCarloGraphByDay(orderName, data);
         }
         monteCarloChart.setModel(xymodel);
     }
 
+    private CategoryModel generateMonteCarloGraphByDay(String orderName, Map<LocalDate, BigDecimal> data) {
+        CategoryModel result = new SimpleCategoryModel();
+
+        List<LocalDate> dates = new ArrayList(data.keySet());
+        Collections.sort(dates);
+        for (LocalDate date: dates) {
+            String labelDate = date.toString();
+            result.setValue(orderName, labelDate, data.get(date));
+        }
+        return result;
+    }
+
+    private CategoryModel generateMonteCarloGraphByWeek(String orderName, Map<Integer, BigDecimal> data) {
+        CategoryModel result = new SimpleCategoryModel();
+
+        List<Integer> weeks = new ArrayList(data.keySet());
+        Collections.sort(weeks);
+        Integer first = weeks.get(0);
+        Integer last = weeks.get(weeks.size() - 1);
+        for (Integer i = first; i <= last; i = i + 1) {
+            String labelDate = "W" + i;
+            BigDecimal probability = data.get(i);
+            if (probability == null) {
+                probability = BigDecimal.ZERO;
+            }
+            result.setValue(orderName, labelDate, probability);
+        }
+
+        return result;
+    }
+
+    private Map<Integer, BigDecimal> groupByWeek(Map<LocalDate, BigDecimal> data) {
+        Map<Integer, BigDecimal> result = new HashMap<Integer, BigDecimal>();
+
+        // Group values of each date by week
+        for (LocalDate date: data.keySet()) {
+            Integer week = Integer.valueOf(date.getWeekOfWeekyear());
+            BigDecimal value = result.get(week);
+            value = (value != null) ? value.add(data.get(date)) : data.get(date);
+            result.put(week, value);
+        }
+        return result;
+    }
+
 }
diff --git a/navalplanner-webapp/src/main/webapp/montecarlo/_montecarlo.zul b/navalplanner-webapp/src/main/webapp/montecarlo/_montecarlo.zul
index 2a8af53cc..44a6fa66a 100644
--- a/navalplanner-webapp/src/main/webapp/montecarlo/_montecarlo.zul
+++ b/navalplanner-webapp/src/main/webapp/montecarlo/_montecarlo.zul
@@ -61,17 +61,24 @@
                     <columns>
                         <column width="200px" />
                         <column />
+                        <column />
                     </columns>
                     <rows>
+                        <row>
+                            <label value="${i18n:_('Group by weeks')}" />
+                            <checkbox id="cbGroupByWeeks"
+                                width="200px" />
+                            <label value="" />
+                        </row>
                         <row>
                             <label value="${i18n:_('Number of iterations')}" />
                             <intbox id="ibIterations"
                                 width="200px"
                                 constraint="no empty:${i18n:_('cannot be null or empty')}" />
+                            <button id="btnRunMonteCarlo" label="${i18n:_('Go!')}" />
                         </row>
                     </rows>
                 </grid>
-                <button id="btnRunMonteCarlo" label="${i18n:_('Go!')}" />
             </hbox>
 
         </window>