diff --git a/htroot/PerformanceQueues_p.java b/htroot/PerformanceQueues_p.java
index a1741ba7e..e0bf584ac 100644
--- a/htroot/PerformanceQueues_p.java
+++ b/htroot/PerformanceQueues_p.java
@@ -289,7 +289,7 @@ public class PerformanceQueues_p {
 
         // table cache settings
         prop.putNum("wordCacheSize", indexSegment.RWIBufferCount());
-        prop.putNum("wordCacheSizeKBytes", rwi == null ? 0 : rwi.getBufferSizeBytes()/1024);
+        prop.putNum("wordCacheSizeKBytes", rwi == null ? 0 : rwi.getBufferSizeBytes() / 1024L);
         prop.putNum("maxURLinCache", rwi == null ? 0 : rwi.getBufferMaxReferences());
         prop.putNum("maxAgeOfCache", rwi == null ? 0 : rwi.getBufferMaxAge() / 1000 / 60); // minutes
         prop.putNum("minAgeOfCache", rwi == null ? 0 : rwi.getBufferMinAge() / 1000 / 60); // minutes
diff --git a/source/net/yacy/cora/util/ByteArray.java b/source/net/yacy/cora/util/ByteArray.java
index e117e9670..f54b9e93a 100644
--- a/source/net/yacy/cora/util/ByteArray.java
+++ b/source/net/yacy/cora/util/ByteArray.java
@@ -44,6 +44,10 @@ public class ByteArray {
     public ByteArray(final byte[] bb) {
         this.buffer = bb;
     }
+    
+    public long usedMemory() {
+        return this.buffer.length;
+    }
 
     public byte[] asBytes() {
         return this.buffer;
diff --git a/source/net/yacy/kelondro/rwi/IndexCell.java b/source/net/yacy/kelondro/rwi/IndexCell.java
index f3ea810b2..7365813af 100644
--- a/source/net/yacy/kelondro/rwi/IndexCell.java
+++ b/source/net/yacy/kelondro/rwi/IndexCell.java
@@ -631,7 +631,7 @@ public final class IndexCell<ReferenceType extends Reference> extends AbstractBu
 
     @Override
     public long getBufferSizeBytes() {
-        return 10000 * this.ram.size(); // guessed; we don't know that exactly because there is no statistics here (expensive, not necessary)
+        return this.ram.usedMemory();
     }
 
     @Override
diff --git a/source/net/yacy/kelondro/rwi/ReferenceContainerCache.java b/source/net/yacy/kelondro/rwi/ReferenceContainerCache.java
index 478a133ce..b3809c1a7 100644
--- a/source/net/yacy/kelondro/rwi/ReferenceContainerCache.java
+++ b/source/net/yacy/kelondro/rwi/ReferenceContainerCache.java
@@ -201,6 +201,16 @@ public final class ReferenceContainerCache<ReferenceType extends Reference> exte
     public int size() {
         return (this.cache == null) ? 0 : this.cache.size();
     }
+    
+    public long usedMemory() {
+        if (this.cache == null) return 0;
+        long b = 0L;
+        for (Map.Entry<ByteArray, ReferenceContainer<ReferenceType>> e: this.cache.entrySet()) {
+            b += e.getKey().usedMemory();
+            b += e.getValue().mem();
+        }
+        return b;
+    }
 
     public boolean isEmpty() {
         if (this.cache == null) return true;