diff --git lucene/suggest/src/java/org/apache/lucene/search/suggest/Lookup.java lucene/suggest/src/java/org/apache/lucene/search/suggest/Lookup.java
index dd35d85..3b4e09c 100644
--- lucene/suggest/src/java/org/apache/lucene/search/suggest/Lookup.java
+++ lucene/suggest/src/java/org/apache/lucene/search/suggest/Lookup.java
@@ -201,4 +201,9 @@ public abstract class Lookup {
    */
   public abstract boolean load(InputStream input) throws IOException;
   
+  /**
+   * Get the size of the underlying lookup implementation in memory
+   * @return ram size of the lookup implementation in bytes
+   */
+  public abstract long sizeInBytes();
 }
diff --git lucene/suggest/src/java/org/apache/lucene/search/suggest/analyzing/AnalyzingInfixSuggester.java lucene/suggest/src/java/org/apache/lucene/search/suggest/analyzing/AnalyzingInfixSuggester.java
index 7d388aa..5d4dc52 100644
--- lucene/suggest/src/java/org/apache/lucene/search/suggest/analyzing/AnalyzingInfixSuggester.java
+++ lucene/suggest/src/java/org/apache/lucene/search/suggest/analyzing/AnalyzingInfixSuggester.java
@@ -72,6 +72,7 @@ import org.apache.lucene.store.Directory;
 import org.apache.lucene.store.FSDirectory;
 import org.apache.lucene.util.BytesRef;
 import org.apache.lucene.util.IOUtils;
+import org.apache.lucene.util.RamUsageEstimator;
 import org.apache.lucene.util.Version;
 
 // TODO:
@@ -599,4 +600,9 @@ public class AnalyzingInfixSuggester extends Lookup implements Closeable {
       dir = null;
     }
   }
+
+  @Override
+  public long sizeInBytes() {
+    return RamUsageEstimator.sizeOf(this);
+  }
 };
diff --git lucene/suggest/src/java/org/apache/lucene/search/suggest/analyzing/AnalyzingSuggester.java lucene/suggest/src/java/org/apache/lucene/search/suggest/analyzing/AnalyzingSuggester.java
index 3187845..4278440 100644
--- lucene/suggest/src/java/org/apache/lucene/search/suggest/analyzing/AnalyzingSuggester.java
+++ lucene/suggest/src/java/org/apache/lucene/search/suggest/analyzing/AnalyzingSuggester.java
@@ -250,6 +250,7 @@ public class AnalyzingSuggester extends Lookup {
   }
 
   /** Returns byte size of the underlying FST. */
+  @Override
   public long sizeInBytes() {
     return fst == null ? 0 : fst.sizeInBytes();
   }
diff --git lucene/suggest/src/java/org/apache/lucene/search/suggest/analyzing/FreeTextSuggester.java lucene/suggest/src/java/org/apache/lucene/search/suggest/analyzing/FreeTextSuggester.java
index 36c22a7..797acae 100644
--- lucene/suggest/src/java/org/apache/lucene/search/suggest/analyzing/FreeTextSuggester.java
+++ lucene/suggest/src/java/org/apache/lucene/search/suggest/analyzing/FreeTextSuggester.java
@@ -198,7 +198,8 @@ public class FreeTextSuggester extends Lookup {
     this.separator = separator;
   }
 
-  /** Returns byte size of the underlying FST. */
+  /** Returns byte size of the underlying FST. */ 
+  @Override
   public long sizeInBytes() {
     if (fst == null) {
       return 0;
diff --git lucene/suggest/src/java/org/apache/lucene/search/suggest/fst/FSTCompletionLookup.java lucene/suggest/src/java/org/apache/lucene/search/suggest/fst/FSTCompletionLookup.java
index 3dbf66d..7c88a3e 100644
--- lucene/suggest/src/java/org/apache/lucene/search/suggest/fst/FSTCompletionLookup.java
+++ lucene/suggest/src/java/org/apache/lucene/search/suggest/fst/FSTCompletionLookup.java
@@ -288,4 +288,9 @@ public class FSTCompletionLookup extends Lookup {
     }
     return true;
   }
+
+  @Override
+  public long sizeInBytes() {
+    return RamUsageEstimator.sizeOf(this);
+  }
 }
diff --git lucene/suggest/src/java/org/apache/lucene/search/suggest/fst/WFSTCompletionLookup.java lucene/suggest/src/java/org/apache/lucene/search/suggest/fst/WFSTCompletionLookup.java
index eb07356..eaff404 100644
--- lucene/suggest/src/java/org/apache/lucene/search/suggest/fst/WFSTCompletionLookup.java
+++ lucene/suggest/src/java/org/apache/lucene/search/suggest/fst/WFSTCompletionLookup.java
@@ -287,4 +287,10 @@ public class WFSTCompletionLookup extends Lookup {
       return left.compareTo(right);
     }  
   };
+
+  /** Returns byte size of the underlying FST. */
+  @Override
+  public long sizeInBytes() {
+    return (fst == null) ? 0 : fst.sizeInBytes();
+  }
 }
diff --git lucene/suggest/src/java/org/apache/lucene/search/suggest/jaspell/JaspellLookup.java lucene/suggest/src/java/org/apache/lucene/search/suggest/jaspell/JaspellLookup.java
index 0482e52..65c4532 100644
--- lucene/suggest/src/java/org/apache/lucene/search/suggest/jaspell/JaspellLookup.java
+++ lucene/suggest/src/java/org/apache/lucene/search/suggest/jaspell/JaspellLookup.java
@@ -31,6 +31,7 @@ import org.apache.lucene.search.suggest.jaspell.JaspellTernarySearchTrie.TSTNode
 import org.apache.lucene.util.BytesRef;
 import org.apache.lucene.util.CharsRef;
 import org.apache.lucene.util.IOUtils;
+import org.apache.lucene.util.RamUsageEstimator;
 import org.apache.lucene.util.UnicodeUtil;
 
 /**
@@ -200,4 +201,10 @@ public class JaspellLookup extends Lookup {
     }
     return true;
   }
+
+  /** Returns byte size of the underlying TST. */
+  @Override
+  public long sizeInBytes() {
+    return RamUsageEstimator.sizeOf(trie);
+  }
 }
diff --git lucene/suggest/src/java/org/apache/lucene/search/suggest/tst/TSTLookup.java lucene/suggest/src/java/org/apache/lucene/search/suggest/tst/TSTLookup.java
index 21ed3ad..59cd5f9 100644
--- lucene/suggest/src/java/org/apache/lucene/search/suggest/tst/TSTLookup.java
+++ lucene/suggest/src/java/org/apache/lucene/search/suggest/tst/TSTLookup.java
@@ -31,6 +31,7 @@ import org.apache.lucene.search.suggest.SortedInputIterator;
 import org.apache.lucene.util.BytesRef;
 import org.apache.lucene.util.CharsRef;
 import org.apache.lucene.util.IOUtils;
+import org.apache.lucene.util.RamUsageEstimator;
 import org.apache.lucene.util.UnicodeUtil;
 
 /**
@@ -219,5 +220,11 @@ public class TSTLookup extends Lookup {
     }
     return true;
   }
+
+  /** Returns byte size of the underlying TST */
+  @Override
+  public long sizeInBytes() {
+    return RamUsageEstimator.sizeOf(autocomplete);
+  }
   
 }
diff --git lucene/suggest/src/test/org/apache/lucene/search/suggest/LookupBenchmarkTest.java lucene/suggest/src/test/org/apache/lucene/search/suggest/LookupBenchmarkTest.java
index 7858a23..4874234 100644
--- lucene/suggest/src/test/org/apache/lucene/search/suggest/LookupBenchmarkTest.java
+++ lucene/suggest/src/test/org/apache/lucene/search/suggest/LookupBenchmarkTest.java
@@ -144,15 +144,7 @@ public class LookupBenchmarkTest extends LuceneTestCase {
     System.err.println("-- RAM consumption");
     for (Class<? extends Lookup> cls : benchmarkClasses) {
       Lookup lookup = buildLookup(cls, dictionaryInput);
-      long sizeInBytes;
-      if (lookup instanceof AnalyzingSuggester) {
-        // Just get size of FST: else we are also measuring
-        // size of MockAnalyzer which is non-trivial and
-        // varies depending on test seed:
-        sizeInBytes = ((AnalyzingSuggester) lookup).sizeInBytes();
-      } else {
-        sizeInBytes = RamUsageEstimator.sizeOf(lookup);
-      }
+      long sizeInBytes = lookup.sizeInBytes();
       System.err.println(
           String.format(Locale.ROOT, "%-15s size[B]:%,13d",
               lookup.getClass().getSimpleName(),