diff --git a/google-cloud-clients/google-cloud-datastore/src/main/java/com/google/cloud/datastore/Entity.java b/google-cloud-clients/google-cloud-datastore/src/main/java/com/google/cloud/datastore/Entity.java
index 69d230179b5a..9d3a0c84510e 100644
--- a/google-cloud-clients/google-cloud-datastore/src/main/java/com/google/cloud/datastore/Entity.java
+++ b/google-cloud-clients/google-cloud-datastore/src/main/java/com/google/cloud/datastore/Entity.java
@@ -89,4 +89,14 @@ public static Builder newBuilder(Key key, FullEntity<?> copyFrom) {
   public static Entity fromPb(com.google.datastore.v1.Entity entityPb) {
     return new Builder().fill(entityPb).build();
   }
+
+  /**
+   * Returns the size in bytes of the protobuf form of the provided entity.
+   *
+   * @param entity object whose size is measured.
+   */
+  public static int calculateSerializedSize(BaseEntity<? extends IncompleteKey> entity) {
+    checkNotNull(entity);
+    return entity.toPb().getSerializedSize();
+  }
 }
diff --git a/google-cloud-clients/google-cloud-datastore/src/test/java/com/google/cloud/datastore/EntityTest.java b/google-cloud-clients/google-cloud-datastore/src/test/java/com/google/cloud/datastore/EntityTest.java
index a4ffe8a2c88b..31baa87fe379 100644
--- a/google-cloud-clients/google-cloud-datastore/src/test/java/com/google/cloud/datastore/EntityTest.java
+++ b/google-cloud-clients/google-cloud-datastore/src/test/java/com/google/cloud/datastore/EntityTest.java
@@ -55,4 +55,9 @@ public void testCopyFromIncompleteEntity() throws Exception {
     assertNotEquals(INCOMPLETE_ENTITY, entity);
     assertEquals(INCOMPLETE_ENTITY.getProperties(), entity.getProperties());
   }
+
+  @Test
+  public void testEntitySize() {
+    assertEquals(ENTITY.toPb().getSerializedSize(), Entity.calculateSerializedSize(ENTITY));
+  }
 }