diff --git a/src/ooxml/java/org/apache/poi/openxml4j/opc/PackagePart.java b/src/ooxml/java/org/apache/poi/openxml4j/opc/PackagePart.java
index 6371c13ce5..56f6a66e91 100644
--- a/src/ooxml/java/org/apache/poi/openxml4j/opc/PackagePart.java
+++ b/src/ooxml/java/org/apache/poi/openxml4j/opc/PackagePart.java
@@ -624,6 +624,13 @@ public abstract class PackagePart implements RelationshipSource {
 	public void setDeleted(boolean isDeleted) {
 		this._isDeleted = isDeleted;
 	}
+	
+	/**
+	 * @return The length of the part in bytes, or -1 if not known
+	 */
+	public long getSize() {
+	   return -1;
+	}
 
 	@Override
 	public String toString() {
diff --git a/src/ooxml/java/org/apache/poi/openxml4j/opc/ZipPackagePart.java b/src/ooxml/java/org/apache/poi/openxml4j/opc/ZipPackagePart.java
index e20311787b..8c0e18502a 100644
--- a/src/ooxml/java/org/apache/poi/openxml4j/opc/ZipPackagePart.java
+++ b/src/ooxml/java/org/apache/poi/openxml4j/opc/ZipPackagePart.java
@@ -113,6 +113,11 @@ public class ZipPackagePart extends PackagePart {
 		return null;
 	}
 
+	@Override
+	public long getSize() {
+		return zipEntry.getSize();
+	}
+
 	@Override
 	public boolean save(OutputStream os) throws OpenXML4JException {
 		return new ZipPartMarshaller().marshall(this, os);
diff --git a/src/ooxml/java/org/apache/poi/openxml4j/opc/internal/MemoryPackagePart.java b/src/ooxml/java/org/apache/poi/openxml4j/opc/internal/MemoryPackagePart.java
index f950e2ca3b..b6c56949d4 100644
--- a/src/ooxml/java/org/apache/poi/openxml4j/opc/internal/MemoryPackagePart.java
+++ b/src/ooxml/java/org/apache/poi/openxml4j/opc/internal/MemoryPackagePart.java
@@ -102,6 +102,11 @@ public final class MemoryPackagePart extends PackagePart {
 		return new MemoryPackagePartOutputStream(this);
 	}
 
+	@Override
+	public long getSize() {
+		return length;
+	}
+
 	public void clear() {
 		data = null;
 		length = 0;
diff --git a/src/ooxml/testcases/org/apache/poi/openxml4j/opc/TestPackage.java b/src/ooxml/testcases/org/apache/poi/openxml4j/opc/TestPackage.java
index b6bc97c185..b4ac8bd7c6 100644
--- a/src/ooxml/testcases/org/apache/poi/openxml4j/opc/TestPackage.java
+++ b/src/ooxml/testcases/org/apache/poi/openxml4j/opc/TestPackage.java
@@ -30,6 +30,7 @@ import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
 import org.apache.poi.openxml4j.exceptions.InvalidOperationException;
 import org.apache.poi.openxml4j.opc.internal.ContentTypeManager;
 import org.apache.poi.openxml4j.opc.internal.FileHelper;
+import org.apache.poi.openxml4j.opc.internal.PackagePropertiesPart;
 import org.apache.poi.util.TempFile;
 import org.apache.poi.util.POILogger;
 import org.apache.poi.util.POILogFactory;
@@ -523,6 +524,35 @@ public final class TestPackage extends TestCase {
         assertTrue(selected.containsKey("/word/theme/theme1.xml"));
         assertTrue(selected.containsKey("/word/webSettings.xml"));
     }
+    
+    public void testGetPartSize() throws Exception {
+       String filepath =  OpenXML4JTestDataSamples.getSampleFileName("sample.docx");
+       OPCPackage pkg = OPCPackage.open(filepath, PackageAccess.READ);
+
+       int checked = 0;
+       for (PackagePart part : pkg.getParts()) {
+          // Can get the size of zip parts
+          if (part.getPartName().getName().equals("/word/document.xml")) {
+             checked++;
+             assertEquals(ZipPackagePart.class, part.getClass());
+             assertEquals(6031l, part.getSize());
+          }
+          if (part.getPartName().getName().equals("/word/fontTable.xml")) {
+             checked++;
+             assertEquals(ZipPackagePart.class, part.getClass());
+             assertEquals(1312l, part.getSize());
+          }
+          
+          // But not from the others
+          if (part.getPartName().getName().equals("/docProps/core.xml")) {
+             checked++;
+             assertEquals(PackagePropertiesPart.class, part.getClass());
+             assertEquals(-1, part.getSize());
+          }
+       }
+       // Ensure we actually found the parts we want to check
+       assertEquals(3, checked);
+    }
 
     public void testReplaceContentType() throws Exception {
         InputStream is = OpenXML4JTestDataSamples.openSampleStream("sample.xlsx");