diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/planner/entities/GenericResourceAllocation.java b/navalplanner-business/src/main/java/org/navalplanner/business/planner/entities/GenericResourceAllocation.java
index beff50a2e..fbaff12b9 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/planner/entities/GenericResourceAllocation.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/planner/entities/GenericResourceAllocation.java
@@ -391,9 +391,9 @@ public class GenericResourceAllocation extends
     }
 
     @Override
-    public int getAssignedHours(ICriterion criterion, LocalDate start,
-            LocalDate endExclusive) {
-        return super.getAssignedHours(start, endExclusive);
+    public EffortDuration getAssignedEffort(ICriterion criterion,
+            LocalDate start, LocalDate endExclusive) {
+        return super.getAssignedDuration(start, endExclusive);
     }
 
 }
diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/planner/entities/ResourceAllocation.java b/navalplanner-business/src/main/java/org/navalplanner/business/planner/entities/ResourceAllocation.java
index e1544bd4d..f917fd4a3 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/planner/entities/ResourceAllocation.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/planner/entities/ResourceAllocation.java
@@ -1660,14 +1660,20 @@ public abstract class ResourceAllocation<T extends DayAssignment> extends
 
     public int getAssignedHours(final Resource resource, LocalDate start,
             LocalDate endExclusive) {
-        return getAssignedDuration(filter(getAssignments(start, endExclusive),
-                new PredicateOnDayAssignment() {
+        return getAssignedEffort(resource, start, endExclusive).roundToHours();
+    }
+
+    public EffortDuration getAssignedEffort(final Resource resource,
+            LocalDate start, LocalDate endExclusive) {
+        return getAssignedDuration(
+                filter(getAssignments(start, endExclusive),
+                        new PredicateOnDayAssignment() {
                             @Override
                             public boolean satisfiedBy(
                                     DayAssignment dayAssignment) {
                                 return dayAssignment.isAssignedTo(resource);
                             }
-                        })).roundToHours();
+                }));
     }
 
     public List<DayAssignment> getAssignments(LocalDate start,
@@ -1680,7 +1686,7 @@ public abstract class ResourceAllocation<T extends DayAssignment> extends
         return getAssignedDuration(start, endExclusive).roundToHours();
     }
 
-    public abstract int getAssignedHours(ICriterion criterion, LocalDate start,
+    public abstract EffortDuration getAssignedEffort(ICriterion criterion, LocalDate start,
             LocalDate endExclusive);
 
     private List<DayAssignment> filter(List<DayAssignment> assignments,
diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/planner/entities/SpecificResourceAllocation.java b/navalplanner-business/src/main/java/org/navalplanner/business/planner/entities/SpecificResourceAllocation.java
index 174ad4c62..b819f54b6 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/planner/entities/SpecificResourceAllocation.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/planner/entities/SpecificResourceAllocation.java
@@ -358,7 +358,7 @@ public class SpecificResourceAllocation extends
     }
 
     @Override
-    public int getAssignedHours(ICriterion criterion, LocalDate startInclusive,
+    public EffortDuration getAssignedEffort(ICriterion criterion, LocalDate startInclusive,
             LocalDate endExclusive) {
         EffortDuration result = EffortDuration.zero();
         for (Interval each : getIntervalsRelatedWith(criterion, startInclusive,
@@ -369,7 +369,7 @@ public class SpecificResourceAllocation extends
             result = result.plus(getAssignedDuration(intervalStart.getDate(),
                     intervalEnd.getDate()));
         }
-        return result.roundToHours();
+        return result;
     }
 
     private List<Interval> getIntervalsRelatedWith(ICriterion criterion,
diff --git a/navalplanner-business/src/main/java/org/navalplanner/business/workingday/EffortDuration.java b/navalplanner-business/src/main/java/org/navalplanner/business/workingday/EffortDuration.java
index 6c3c31373..3950e4b1b 100644
--- a/navalplanner-business/src/main/java/org/navalplanner/business/workingday/EffortDuration.java
+++ b/navalplanner-business/src/main/java/org/navalplanner/business/workingday/EffortDuration.java
@@ -28,6 +28,7 @@ import java.util.EnumMap;
 import java.util.Map.Entry;
 
 import org.apache.commons.lang.Validate;
+import org.apache.commons.lang.math.Fraction;
 
 /**
  * <p>
@@ -184,6 +185,10 @@ public class EffortDuration implements Comparable<EffortDuration> {
         return seconds / other.seconds;
     }
 
+    public Fraction divivedBy(EffortDuration effortAssigned) {
+        return Fraction.getFraction(this.seconds, effortAssigned.seconds);
+    }
+
     /**
      * Calculates the remainder resulting of doing the integer division of both
      * durations
diff --git a/navalplanner-webapp/src/main/java/org/navalplanner/web/resourceload/LoadPeriodGenerator.java b/navalplanner-webapp/src/main/java/org/navalplanner/web/resourceload/LoadPeriodGenerator.java
index 61e3627fe..e2957e1bc 100644
--- a/navalplanner-webapp/src/main/java/org/navalplanner/web/resourceload/LoadPeriodGenerator.java
+++ b/navalplanner-webapp/src/main/java/org/navalplanner/web/resourceload/LoadPeriodGenerator.java
@@ -24,7 +24,6 @@ package org.navalplanner.web.resourceload;
 import static org.navalplanner.business.workingday.IntraDayDate.max;
 import static org.navalplanner.business.workingday.IntraDayDate.min;
 
-import java.math.BigDecimal;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
@@ -34,6 +33,7 @@ import java.util.List;
 import java.util.Map;
 
 import org.apache.commons.lang.Validate;
+import org.apache.commons.lang.math.Fraction;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.navalplanner.business.planner.entities.ResourceAllocation;
@@ -200,36 +200,37 @@ abstract class LoadPeriodGenerator {
                             + allocationsOnInterval + ". LoadPeriod ignored");
             return null;
         }
-        int totalWorkHours = getTotalWorkHours();
-        int hoursAssigned = getHoursAssigned();
+        EffortDuration totalEffort = getTotalAvailableEffort();
+        EffortDuration effortAssigned = getEffortAssigned();
         return new LoadPeriod(start.getDate(), end.asExclusiveEnd(),
-                totalWorkHours, hoursAssigned,
-                new LoadLevel(calculateLoadPercentage(totalWorkHours,
-                        hoursAssigned)));
+                totalEffort.roundToHours(), effortAssigned.roundToHours(),
+                new LoadLevel(calculateLoadPercentage(totalEffort,
+                        effortAssigned)));
     }
 
-    protected abstract int getTotalWorkHours();
+    protected abstract EffortDuration getTotalAvailableEffort();
 
-    private static int calculateLoadPercentage(int totalWorkHours,
-            int hoursAssigned) {
-        if (totalWorkHours == 0) {
-            return hoursAssigned == 0 ? 0 : Integer.MAX_VALUE;
+    private static int calculateLoadPercentage(EffortDuration totalEffort,
+            EffortDuration effortAssigned) {
+        if (totalEffort.isZero()) {
+            return effortAssigned.isZero() ? 0 : Integer.MAX_VALUE;
         }
-        double proportion = hoursAssigned / (double) totalWorkHours;
-        return new BigDecimal(proportion).scaleByPowerOfTen(2).intValue();
+        Fraction fraction = totalEffort.divivedBy(effortAssigned);
+        Fraction percentage = fraction.multiplyBy(Fraction.getFraction(100, 1));
+        return percentage.intValue();
     }
 
-    protected abstract int getHoursAssigned();
+    protected abstract EffortDuration getEffortAssigned();
 
-    protected final int sumAllocations() {
-        int sum = 0;
+    protected final EffortDuration sumAllocations() {
+        EffortDuration sum = EffortDuration.zero();
         for (ResourceAllocation<?> resourceAllocation : allocationsOnInterval) {
-            sum += getAssignedHoursFor(resourceAllocation);
+            sum = sum.plus(getAssignedEffortFor(resourceAllocation));
         }
         return sum;
     }
 
-    protected abstract int getAssignedHoursFor(
+    protected abstract EffortDuration getAssignedEffortFor(
             ResourceAllocation<?> resourceAllocation);
 
     public IntraDayDate getStart() {
@@ -272,18 +273,19 @@ class LoadPeriodGeneratorOnResource extends LoadPeriodGenerator {
     }
 
     @Override
-    protected int getTotalWorkHours() {
-        return resource.getTotalEffortFor(start, end, criterion).roundToHours();
+    protected EffortDuration getTotalAvailableEffort() {
+        return resource.getTotalEffortFor(start, end, criterion);
     }
 
     @Override
-    protected int getAssignedHoursFor(ResourceAllocation<?> resourceAllocation) {
-        return resourceAllocation.getAssignedHours(resource, start.getDate(),
+    protected EffortDuration getAssignedEffortFor(
+            ResourceAllocation<?> resourceAllocation) {
+        return resourceAllocation.getAssignedEffort(resource, start.getDate(),
                 end.asExclusiveEnd());
     }
 
     @Override
-    protected int getHoursAssigned() {
+    protected EffortDuration getEffortAssigned() {
         return sumAllocations();
     }
 
@@ -323,22 +325,23 @@ class LoadPeriodGeneratorOnCriterion extends LoadPeriodGenerator {
     }
 
     @Override
-    protected int getAssignedHoursFor(ResourceAllocation<?> resourceAllocation) {
-        return resourceAllocation.getAssignedHours(criterion, start.getDate(),
+    protected EffortDuration getAssignedEffortFor(
+            ResourceAllocation<?> resourceAllocation) {
+        return resourceAllocation.getAssignedEffort(criterion, start.getDate(),
                 end.asExclusiveEnd());
     }
 
     @Override
-    protected int getTotalWorkHours() {
+    protected EffortDuration getTotalAvailableEffort() {
         EffortDuration sum = EffortDuration.zero();
         for (Resource resource : resourcesSatisfyingCriterionAtSomePoint) {
             sum = sum.plus(resource.getTotalEffortFor(start, end, criterion));
         }
-        return sum.roundToHours();
+        return sum;
     }
 
     @Override
-    protected int getHoursAssigned() {
+    protected EffortDuration getEffortAssigned() {
         return sumAllocations();
     }