diff --git a/lucene/CHANGES.txt b/lucene/CHANGES.txt
index 979f742b3082..fe51f3e48680 100644
--- a/lucene/CHANGES.txt
+++ b/lucene/CHANGES.txt
@@ -386,6 +386,9 @@ Bug Fixes
 * GITHUB#16389: Fix double-counting of the underlying Automaton in
   AutomatonQuery#ramBytesUsed. (Sasilekha R)
 
+* GITHUB#16405: PointInSetQuery#ramBytesUsed now accounts for the retained
+  lowerPoint and upperPoint bounds arrays. (Sasilekha R)
+
 * GITHUB#16367: HNSW graph construction now periodically checks whether the surrounding merge has
   been aborted, so IndexWriter#rollback and abortMerges no longer block until the entire graph is
   built. (Jeho Jeong)
diff --git a/lucene/core/src/java/org/apache/lucene/search/PointInSetQuery.java b/lucene/core/src/java/org/apache/lucene/search/PointInSetQuery.java
index 431c5b87b25d..90bca4e8def7 100644
--- a/lucene/core/src/java/org/apache/lucene/search/PointInSetQuery.java
+++ b/lucene/core/src/java/org/apache/lucene/search/PointInSetQuery.java
@@ -136,7 +136,9 @@ protected PointInSetQuery(String field, int numDims, int bytesPerDim, Stream pac
     ramBytesUsed =
         BASE_RAM_BYTES
             + RamUsageEstimator.sizeOfObject(field)
-            + RamUsageEstimator.sizeOfObject(sortedPackedPoints);
+            + RamUsageEstimator.sizeOfObject(sortedPackedPoints)
+            + RamUsageEstimator.sizeOfObject(lowerPoint)
+            + RamUsageEstimator.sizeOfObject(upperPoint);
   }
 
   @Override
diff --git a/lucene/core/src/test/org/apache/lucene/search/TestPointQueries.java b/lucene/core/src/test/org/apache/lucene/search/TestPointQueries.java
index a61adf527fff..2b3a91b55bf7 100644
--- a/lucene/core/src/test/org/apache/lucene/search/TestPointQueries.java
+++ b/lucene/core/src/test/org/apache/lucene/search/TestPointQueries.java
@@ -62,11 +62,13 @@
 import org.apache.lucene.tests.index.RandomIndexWriter;
 import org.apache.lucene.tests.search.FixedBitSetCollector;
 import org.apache.lucene.tests.util.LuceneTestCase;
+import org.apache.lucene.tests.util.RamUsageTester;
 import org.apache.lucene.tests.util.TestUtil;
 import org.apache.lucene.util.BytesRef;
 import org.apache.lucene.util.FixedBitSet;
 import org.apache.lucene.util.IOUtils;
 import org.apache.lucene.util.NumericUtils;
+import org.apache.lucene.util.RamUsageEstimator;
 import org.apache.lucene.util.bkd.BKDConfig;
 import org.junit.BeforeClass;
 
@@ -2630,4 +2632,39 @@ protected String toString(byte[] point) {
             });
     assertEquals("values are out of order: saw [2] before [1]", expected.getMessage());
   }
+
+  public void testRamBytesUsedIncludesBoundsArrays() {
+    // The constructor allocates lowerPoint/upperPoint and retains them for the whole
+    // lifetime of the query (scorerSupplier uses them for a per-segment pre-check).
+    // Both must contribute to ramBytesUsed().
+    PointInSetQuery q =
+        (PointInSetQuery) BinaryPoint.newSetQuery("f", new byte[] {1, 2, 3, 4, 5, 6, 7, 8});
+    assertNotNull(q.lowerPoint);
+    assertNotNull(q.upperPoint);
+    long expected =
+        RamUsageEstimator.shallowSizeOfInstance(PointInSetQuery.class)
+            + RamUsageEstimator.sizeOfObject(q.field)
+            + RamUsageEstimator.sizeOfObject(q.sortedPackedPoints)
+            + RamUsageEstimator.sizeOfObject(q.lowerPoint)
+            + RamUsageEstimator.sizeOfObject(q.upperPoint);
+    assertEquals(expected, q.ramBytesUsed());
+  }
+
+  public void testRamBytesUsedMatchesActualWithinTolerance() {
+    // Independent cross-check against a full object-graph walk; guards against the
+    // case where the byte-exact test and the implementation drift together.
+    // Mirrors TestTermInSetQuery#testRamBytesUsed (many entries, 5% margin).
+    final int numPoints = 10000 + random().nextInt(1000);
+    final byte[][] values = new byte[numPoints][];
+    for (int i = 0; i < numPoints; i++) {
+      values[i] = new byte[8];
+      random().nextBytes(values[i]);
+    }
+    PointInSetQuery query = (PointInSetQuery) BinaryPoint.newSetQuery("f", values);
+    final long actualRamBytesUsed = RamUsageTester.ramUsed(query);
+    final long expectedRamBytesUsed = query.ramBytesUsed();
+    // error margin within 5%
+    assertEquals(
+        (double) expectedRamBytesUsed, (double) actualRamBytesUsed, actualRamBytesUsed / 20.d);
+  }
 }