diff --git a/hbase-common/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileContext.java b/hbase-common/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileContext.java
index b5ccda21a44..6074f10df26 100644
--- a/hbase-common/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileContext.java
+++ b/hbase-common/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileContext.java
@@ -34,6 +34,11 @@ import org.apache.yetus.audience.InterfaceAudience;
  */
 @InterfaceAudience.Private
 public class HFileContext implements HeapSize, Cloneable {
+  public static final int FIXED_OVERHEAD = ClassSize.align(ClassSize.OBJECT +
+      // Algorithm, checksumType, encoding, Encryption.Context, hfileName reference
+      5 * ClassSize.REFERENCE + 2 * Bytes.SIZEOF_INT +
+      // usesHBaseChecksum, includesMvcc, includesTags and compressTags
+      4 * Bytes.SIZEOF_BOOLEAN + Bytes.SIZEOF_LONG);
 
   public static final int DEFAULT_BYTES_PER_CHECKSUM = 16 * 1024;
 
@@ -188,19 +193,13 @@ public class HFileContext implements HeapSize, Cloneable {
   }
 
   /**
-   * HeapSize implementation
-   * NOTE : The heapsize should be altered as and when new state variable are added
+   * HeapSize implementation. NOTE : The heapsize should be altered as and when new state variable
+   * are added
    * @return heap size of the HFileContext
    */
   @Override
   public long heapSize() {
-    long size = ClassSize.align(ClassSize.OBJECT +
-        // Algorithm reference, encodingon, checksumtype, Encryption.Context reference
-        5 * ClassSize.REFERENCE +
-        2 * Bytes.SIZEOF_INT +
-        // usesHBaseChecksum, includesMvcc, includesTags and compressTags
-        4 * Bytes.SIZEOF_BOOLEAN +
-        Bytes.SIZEOF_LONG);
+    long size = FIXED_OVERHEAD;
     if (this.hfileName != null) {
       size += ClassSize.STRING + this.hfileName.length();
     }
diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java
index 8ab5649735f..c1a071bf27f 100644
--- a/hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java
+++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileBlock.java
@@ -113,6 +113,14 @@ import org.apache.hbase.thirdparty.com.google.common.base.Preconditions;
 @InterfaceAudience.Private
 public class HFileBlock implements Cacheable {
   private static final Logger LOG = LoggerFactory.getLogger(HFileBlock.class);
+  public static final int FIXED_OVERHEAD = ClassSize.align(ClassSize.OBJECT +
+     // BlockType, ByteBuff, MemoryType, HFileContext, ByteBuffAllocator
+      5 * ClassSize.REFERENCE +
+      // On-disk size, uncompressed size, and next block's on-disk size
+      // bytePerChecksum and onDiskDataSize
+      4 * Bytes.SIZEOF_INT +
+      // This and previous block offset
+      2 * Bytes.SIZEOF_LONG);
 
   // Block Header fields.
 
@@ -740,24 +748,12 @@ public class HFileBlock implements Cacheable {
 
   @Override
   public long heapSize() {
-    long size = ClassSize.align(
-        ClassSize.OBJECT +
-        // Block type, multi byte buffer, MemoryType and meta references
-        4 * ClassSize.REFERENCE +
-        // On-disk size, uncompressed size, and next block's on-disk size
-        // bytePerChecksum and onDiskDataSize
-        4 * Bytes.SIZEOF_INT +
-        // This and previous block offset
-        2 * Bytes.SIZEOF_LONG +
-        // Heap size of the meta object. meta will be always not null.
-        fileContext.heapSize()
-    );
-
+    long size = FIXED_OVERHEAD;
+    size += fileContext.heapSize();
     if (buf != null) {
       // Deep overhead of the byte buffer. Needs to be aligned separately.
       size += ClassSize.align(buf.capacity() + MULTI_BYTE_BUFFER_HEAP_SIZE);
     }
-
     return ClassSize.align(size);
   }
 
diff --git a/hbase-server/src/test/java/org/apache/hadoop/hbase/io/TestHeapSize.java b/hbase-server/src/test/java/org/apache/hadoop/hbase/io/TestHeapSize.java
index 993503d567b..71ffb87c266 100644
--- a/hbase-server/src/test/java/org/apache/hadoop/hbase/io/TestHeapSize.java
+++ b/hbase-server/src/test/java/org/apache/hadoop/hbase/io/TestHeapSize.java
@@ -43,6 +43,8 @@ import org.apache.hadoop.hbase.client.Delete;
 import org.apache.hadoop.hbase.client.Mutation;
 import org.apache.hadoop.hbase.client.Put;
 import org.apache.hadoop.hbase.io.hfile.BlockCacheKey;
+import org.apache.hadoop.hbase.io.hfile.HFileBlock;
+import org.apache.hadoop.hbase.io.hfile.HFileContext;
 import org.apache.hadoop.hbase.io.hfile.LruBlockCache;
 import org.apache.hadoop.hbase.io.hfile.LruCachedBlock;
 import org.apache.hadoop.hbase.regionserver.CSLMImmutableSegment;
@@ -515,6 +517,20 @@ public class TestHeapSize  {
     // any of these classes are modified without updating overhead sizes.
   }
 
+  @Test
+  public void testHFileBlockSize() throws IOException {
+    long expected;
+    long actual;
+
+    actual = HFileContext.FIXED_OVERHEAD;
+    expected = ClassSize.estimateBase(HFileContext.class, false);
+    assertEquals(expected, actual);
+
+    actual = HFileBlock.FIXED_OVERHEAD;
+    expected = ClassSize.estimateBase(HFileBlock.class, false);
+    assertEquals(expected, actual);
+  }
+
   @Test
   public void testMutations(){
     Class<?> cl;