diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/calendars/entities/BaseCalendar.java b/navalplanner-business/src/main/java/org/navalplanner/business/calendars/entities/BaseCalendar.java
index 35345c736..3ca65c21a 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/calendars/entities/BaseCalendar.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/calendars/entities/BaseCalendar.java
@@ -891,10 +891,17 @@ public class BaseCalendar extends IntegrationEntity implements ICalendar {
     @Override
     public EffortDuration asDurationOn(LocalDate day,
             ResourcesPerDay resourcesPerDay) {
-        final EffortDuration workableHours = getWorkableTimeAt(day);
-        return limitOverAssignability(day,
-                resourcesPerDay.asDurationGivenWorkingDayOf(workableHours),
-                workableHours);
+        return asDurationOn(PartialDay.wholeDay(day), resourcesPerDay);
+    }
+
+    @Override
+    public EffortDuration asDurationOn(PartialDay day, ResourcesPerDay amount) {
+        EffortDuration workableDuration = day
+                .limitDuration(getWorkableTimeAt(day.getDate()));
+        EffortDuration asDuration = amount
+                .asDurationGivenWorkingDayOf(workableDuration);
+        return limitOverAssignability(day.getDate(), asDuration,
+                workableDuration);
     }
 
     private EffortDuration limitOverAssignability(LocalDate day,
diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/calendars/entities/CombinedWorkHours.java b/navalplanner-business/src/main/java/org/navalplanner/business/calendars/entities/CombinedWorkHours.java
index aa87a4df2..5f5c340d6 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/calendars/entities/CombinedWorkHours.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/calendars/entities/CombinedWorkHours.java
@@ -90,6 +90,11 @@ public abstract class CombinedWorkHours implements ICalendar {
 
     @Override
     public EffortDuration asDurationOn(LocalDate day, ResourcesPerDay amount) {
+        return asDurationOn(PartialDay.wholeDay(day), amount);
+    }
+
+    @Override
+    public EffortDuration asDurationOn(PartialDay day, ResourcesPerDay amount) {
         EffortDuration result = null;
         for (ICalendar each : calendars) {
             result = result == null ? each.asDurationOn(day, amount)
diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/calendars/entities/ICalendar.java b/navalplanner-business/src/main/java/org/navalplanner/business/calendars/entities/ICalendar.java
index 78a286f80..578642ada 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/calendars/entities/ICalendar.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/calendars/entities/ICalendar.java
@@ -37,6 +37,16 @@ public interface ICalendar {
      */
     public EffortDuration asDurationOn(LocalDate day, ResourcesPerDay amount);
 
+    /**
+     * Translates the received amount into the corresponding duration at the
+     * given date. It takes into account the partial capacity of the day.
+     *
+     * @param day
+     * @param amount
+     * @return
+     */
+    public EffortDuration asDurationOn(PartialDay day, ResourcesPerDay amount);
+
     /**
      * Calculates the capacity duration at a given date. It means all the time
      * that could be worked without having overtime
diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/calendars/entities/SameWorkHoursEveryDay.java b/navalplanner-business/src/main/java/org/navalplanner/business/calendars/entities/SameWorkHoursEveryDay.java
index c6ca312d3..ad6a331ac 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/calendars/entities/SameWorkHoursEveryDay.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/calendars/entities/SameWorkHoursEveryDay.java
@@ -54,6 +54,11 @@ public class SameWorkHoursEveryDay implements ICalendar {
 
     @Override
     public EffortDuration asDurationOn(LocalDate day, ResourcesPerDay amount) {
+        return asDurationOn(PartialDay.wholeDay(day), amount);
+    }
+
+    @Override
+    public EffortDuration asDurationOn(PartialDay day, ResourcesPerDay amount) {
         return amount.asDurationGivenWorkingDayOf(getCapacityOn(day));
     }
 
diff --git a/navalplanner-business/src/test/java/org/navalplanner/business/test/planner/entities/SpecificResourceAllocationTest.java b/navalplanner-business/src/test/java/org/navalplanner/business/test/planner/entities/SpecificResourceAllocationTest.java
index afca7ad1e..ee4f82e59 100644
--- a/navalplanner-business/src/test/java/org/navalplanner/business/test/planner/entities/SpecificResourceAllocationTest.java
+++ b/navalplanner-business/src/test/java/org/navalplanner/business/test/planner/entities/SpecificResourceAllocationTest.java
@@ -57,6 +57,7 @@ import org.navalplanner.business.planner.entities.Task;
 import org.navalplanner.business.resources.entities.Worker;
 import org.navalplanner.business.workingday.EffortDuration;
 import org.navalplanner.business.workingday.IntraDayDate;
+import org.navalplanner.business.workingday.IntraDayDate.PartialDay;
 import org.navalplanner.business.workingday.ResourcesPerDay;
 
 public class SpecificResourceAllocationTest {
@@ -81,10 +82,15 @@ public class SpecificResourceAllocationTest {
         this.calendar = createNiceMock(ResourceCalendar.class);
         expect(this.calendar.getCapacityOn(isA(LocalDate.class)))
                 .andReturn(EffortDuration.hours(hours)).anyTimes();
+        IAnswer<? extends EffortDuration> asDurationAnswer = asDurationOnAnswer(hours(hours));
         expect(
                 this.calendar.asDurationOn(isA(LocalDate.class),
-                        isA(ResourcesPerDay.class))).andAnswer(
-                asDurationOnAnswer(hours(hours))).anyTimes();
+                        isA(ResourcesPerDay.class)))
+                .andAnswer(asDurationAnswer).anyTimes();
+        expect(
+                this.calendar.asDurationOn(isA(PartialDay.class),
+                        isA(ResourcesPerDay.class)))
+                .andAnswer(asDurationAnswer).anyTimes();
         expect(this.calendar.getAvailability()).andReturn(
                 AvailabilityTimeLine.allValid()).anyTimes();
         replay(this.calendar);
@@ -134,8 +140,14 @@ public class SpecificResourceAllocationTest {
 
             @Override
             public Integer answer() throws Throwable {
-                LocalDate date = (LocalDate) EasyMock
+                Object argument = EasyMock
                         .getCurrentArguments()[0];
+                LocalDate date;
+                if (argument instanceof LocalDate) {
+                    date = (LocalDate) argument;
+                }else{
+                    date = ((PartialDay) argument).getDate();
+                }
                 int hours;
                 if (answersForDates.containsKey(date)) {
                     hours = answersForDates.get(date);
@@ -155,6 +167,10 @@ public class SpecificResourceAllocationTest {
                 this.calendar.asDurationOn(isA(LocalDate.class),
                         isA(ResourcesPerDay.class))).andAnswer(
                 effortAnswer).anyTimes();
+        expect(
+                this.calendar.asDurationOn(isA(PartialDay.class),
+                        isA(ResourcesPerDay.class))).andAnswer(effortAnswer)
+                .anyTimes();
         expect(this.calendar.getAvailability()).andReturn(
                 AvailabilityTimeLine.allValid()).anyTimes();
         replay(this.calendar);