diff --git a/pom.xml b/pom.xml
index 8c879de44..3f565c3c6 100755
--- a/pom.xml
+++ b/pom.xml
@@ -212,6 +212,7 @@
             <version>1.5.0</version>
             <scope>test</scope>
         </dependency>
+
     </dependencies>
 
     <build>
diff --git a/src/main/java/net/openhft/chronicle/map/ChronicleMap.java b/src/main/java/net/openhft/chronicle/map/ChronicleMap.java
index 6618dc2ac..f1d42cdbf 100755
--- a/src/main/java/net/openhft/chronicle/map/ChronicleMap.java
+++ b/src/main/java/net/openhft/chronicle/map/ChronicleMap.java
@@ -213,5 +213,36 @@ public interface ChronicleMap<K, V> extends ConcurrentMap<K, V>,
      * @return the value Class or UnresolvedType if unknown.
      */
     Type valueType();
-}
 
+    /**
+     * @return the amount of free space in the map as  a percentage.
+     * When the free space gets low ( around 5% ) the map will automatically expand. The
+     * number of times it can automatically expand is based on the
+     * {@code net.openhft.chronicle.map.ChronicleMapBuilder#maxBloatFactor}. If the map
+     * expands you will see an increase in the available free space. It is not possible to
+     * expand the chronicle map manually.
+     *
+     * see also {@see net.openhft.chronicle.map.ChronicleMap#remainingAutoResizes} as these operations are related.
+     */
+    default short percentageFreeSpace() {
+        throw new UnsupportedOperationException("todo");
+    }
+
+    /**
+     * @return the number of times in the future the map can expand its capacity
+     * ( by expending capacity we mean the number of possible entries that
+     * Can be stored into the map), the map will expand automatically, however, there is an upper limit to the
+     * number of times the map can expand.
+     * This limit is set via the {@code net.openhft.chronicle.map.ChronicleMapBuilder#maxBloatFactor} if
+     * the {@code remainingResizes} drops to zero,
+     * then the map is no longer able to resize, if subsequently, the free space
+     * ( see  {@link net.openhft.chronicle.map.ChronicleMap#percentageFreeSpace}) if the map becomes low ( around 5% ),
+     * the map will not be able to take more entries and will fail with an {@code
+     * java.lang.IllegalStateException} for production systems it is recommended you periodically monitor this result and the both the
+     * {@link net.openhft.chronicle.map.ChronicleMap#percentageFreeSpace}.
+     */
+    default int remainingAutoResizes() {
+        throw new UnsupportedOperationException("todo");
+    }
+
+}
\ No newline at end of file
diff --git a/src/main/java/net/openhft/chronicle/map/ChronicleMapBuilder.java b/src/main/java/net/openhft/chronicle/map/ChronicleMapBuilder.java
index 7c3927b25..98b3d004a 100755
--- a/src/main/java/net/openhft/chronicle/map/ChronicleMapBuilder.java
+++ b/src/main/java/net/openhft/chronicle/map/ChronicleMapBuilder.java
@@ -204,7 +204,7 @@ public final class ChronicleMapBuilder<K, V> implements
     private int maxChunksPerEntry = -1;
     private int alignment = UNDEFINED_ALIGNMENT_CONFIG;
     private long entries = -1L;
-    private double maxBloatFactor = 1.0;
+    double maxBloatFactor = 1.0;
     private boolean allowSegmentTiering = true;
     private double nonTieredSegmentsPercentile = 0.99999;
     private boolean aligned64BitMemoryOperationsAtomic = OS.is64Bit();
diff --git a/src/main/java/net/openhft/chronicle/map/VanillaChronicleMap.java b/src/main/java/net/openhft/chronicle/map/VanillaChronicleMap.java
index 78d93b377..d385f8cc6 100755
--- a/src/main/java/net/openhft/chronicle/map/VanillaChronicleMap.java
+++ b/src/main/java/net/openhft/chronicle/map/VanillaChronicleMap.java
@@ -16,6 +16,9 @@
 
 package net.openhft.chronicle.map;
 
+import impl.CompiledMapIterationContext;
+import impl.CompiledMapQueryContext;
+import net.openhft.chronicle.algo.bitset.ReusableBitSet;
 import net.openhft.chronicle.algo.hashing.LongHashFunction;
 import net.openhft.chronicle.bytes.Bytes;
 import net.openhft.chronicle.bytes.BytesStore;
@@ -34,7 +37,9 @@ import net.openhft.chronicle.hash.serialization.DataAccess;
 import net.openhft.chronicle.hash.serialization.SizeMarshaller;
 import net.openhft.chronicle.hash.serialization.SizedReader;
 import net.openhft.chronicle.hash.serialization.impl.SerializationBuilder;
-import net.openhft.chronicle.map.impl.*;
+import net.openhft.chronicle.map.impl.IterationContext;
+import net.openhft.chronicle.map.impl.NullReturnValue;
+import net.openhft.chronicle.map.impl.QueryContextInterface;
 import net.openhft.chronicle.map.impl.ret.InstanceReturnValue;
 import net.openhft.chronicle.set.ChronicleSet;
 import net.openhft.chronicle.wire.WireIn;
@@ -51,11 +56,14 @@ import java.util.function.Function;
 
 import static net.openhft.chronicle.map.ChronicleMapBuilder.greatestCommonDivisor;
 
+@SuppressWarnings("JavadocReference")
 public class VanillaChronicleMap<K, V, R>
         extends VanillaChronicleHash<K, MapEntry<K, V>, MapSegmentContext<K, V, ?>,
         ExternalMapQueryContext<K, V, ?>>
         implements AbstractChronicleMap<K, V> {
 
+    private final double maxBloatFactor;
+
     public SizeMarshaller valueSizeMarshaller;
     public SizedReader<V> valueReader;
     public DataAccess<V> valueDataAccess;
@@ -98,6 +106,7 @@ public class VanillaChronicleMap<K, V, R>
         valueSizeMarshaller = valueBuilder.sizeMarshaller();
         valueReader = valueBuilder.reader();
         valueDataAccess = valueBuilder.dataAccess();
+        maxBloatFactor = builder.maxBloatFactor;
 
         constantlySizedEntry = builder.constantlySizedEntries();
 
@@ -226,6 +235,51 @@ public class VanillaChronicleMap<K, V, R>
         return valueClass;
     }
 
+    private long tiersUsed() {
+        return globalMutableState().getExtraTiersInUse();
+    }
+
+    private long maxTiers() {
+        return (long) (maxBloatFactor * actualSegments);
+    }
+
+    @Override
+    public int remainingAutoResizes() {
+        return (int) (maxTiers() - tiersUsed());
+    }
+
+    @Override
+    public short percentageFreeSpace() {
+
+        double totalUsed = 0;
+        double totalSize = 0;
+
+        try (IterationContext<K, V, ?> c = iterationContext()) {
+            for (int segmentIndex = 0; segmentIndex < segments(); segmentIndex++) {
+                c.initSegmentIndex(segmentIndex);
+
+                if (!(c instanceof CompiledMapIterationContext))
+                    continue;
+                CompiledMapIterationContext c1 = (CompiledMapIterationContext) c;
+
+                c1.goToFirstTier();
+                ReusableBitSet freeList = c1.freeList();
+                totalUsed += freeList.cardinality();
+                totalSize += freeList.logicalSize();
+
+                while (c1.hasNextTier()) {
+                    c1.nextTier();
+                    ReusableBitSet freeList0 = c1.freeList();
+                    totalUsed += freeList0.cardinality();
+                    totalSize += freeList.logicalSize();
+                }
+
+            }
+        }
+
+        return (short) (100 - (int) (100 * totalUsed / totalSize));
+    }
+
     @NotNull
     @Override
     public final Closeable acquireContext(K key, V usingValue) {
diff --git a/src/test/java/net/openhft/chronicle/map/jsr166/map/ChronicleMapTest.java b/src/test/java/net/openhft/chronicle/map/jsr166/map/ChronicleMapTest.java
index 02a71c560..8ce65c4ba 100644
--- a/src/test/java/net/openhft/chronicle/map/jsr166/map/ChronicleMapTest.java
+++ b/src/test/java/net/openhft/chronicle/map/jsr166/map/ChronicleMapTest.java
@@ -19,6 +19,7 @@ package net.openhft.chronicle.map.jsr166.map;
 import net.openhft.chronicle.map.ChronicleMap;
 import net.openhft.chronicle.map.ChronicleMapBuilder;
 import net.openhft.chronicle.map.jsr166.JSR166TestCase;
+import org.junit.Assert;
 import org.junit.Test;
 
 import java.io.IOException;
@@ -670,40 +671,37 @@ public class ChronicleMapTest extends JSR166TestCase {
         }
     }
 
-    /**
-     * A deserialized map equals original
-     */
-  /*  @Test public void testSerialization()   {
-        Map x = map5();
-        Map y = serialClone(x);
+    @Test
+    public void testPercentageComplete() {
 
-        assertNotSame(x, y);
-        assertEquals(x.size(), y.size());
-        assertEquals(x, y);
-        assertEquals(y, x);
-    }*/
+        try (ChronicleMap<Integer, Integer> map = ChronicleMap
+                .of(Integer.class, Integer.class)
+                .entries(1600)
+                .actualSegments(3)
+                .maxBloatFactor(2)
+                .create()) {
+
+            long remainingAutoResizes = 0;
+            short percentageFreeSpace = 0;
+            try {
+                for (int i = 0; ; i++) {
+
+                    map.put(i, 0);
+                    remainingAutoResizes = map.remainingAutoResizes();
+                    percentageFreeSpace = map.percentageFreeSpace();
+
+                }
+            } catch (IllegalStateException e) {
+                if (e.getMessage().contains("Attempt to allocate")) {
+                    Assert.assertEquals(0, (int) remainingAutoResizes);
+                    Assert.assertTrue(percentageFreeSpace < 6);
+                    return;
+                }
+                Assert.fail();
+            }
 
-    /**
-     * TODO : SetValue of an EntrySet entry sets value in the map.
-     */
-    /*@Test public void testSetValueWriteThrough() {
-        // Adapted from a bug report by Eric Zoerner
-        ChronicleMap map = newShmIntString(2, 5.0f, 1);
-        assertTrue(map.isEmpty());
-        for (int i = 0; i < 20; i++)
-            map.put(new Integer(i), new Integer(i));
-        assertFalse(map.isEmpty());
-        Map.Entry entry1 = (Map.Entry) map.entrySet().iterator().next();
-        // Unless it happens to be first (in which case remainder of
-        // test is skipped), remove a possibly-colliding key from map
-        // which, under some implementations, may cause entry1 to be
-        // cloned in map
-        if (!entry1.getKey().equals(new Integer(16))) {
-            map.remove(new Integer(16));
-            entry1.setValue("XYZ");
-            assertTrue(map.containsValue("XYZ")); // fails if write-through broken
         }
-    }*/
+    }
 
 }