diff --git a/Modules/Core/Common/include/itkImageConstIterator.h b/Modules/Core/Common/include/itkImageConstIterator.h
index ec5c9cca7dc..58723f1f47a 100644
--- a/Modules/Core/Common/include/itkImageConstIterator.h
+++ b/Modules/Core/Common/include/itkImageConstIterator.h
@@ -295,14 +295,22 @@ class ITK_TEMPLATE_EXPORT ImageConstIterator
     return (m_Buffer + m_Offset) > (it.m_Buffer + it.m_Offset);
   }
 
-  /** Get the index. This provides a read only reference to the index.
-   * This causes the index to be calculated from pointer arithmetic and is
-   * therefore an expensive operation.
+  /** Computes the index. Internally calls ImageBase::ComputeIndex, which may be a relatively expensive operation.
    * \sa SetIndex */
+  [[nodiscard]] IndexType
+  ComputeIndex() const
+  {
+    return m_Image->ComputeIndex(static_cast<OffsetValueType>(m_Offset));
+  }
+
+  /** Computes and returns the index. This may be a relatively expensive operation.
+   * \note It is often preferable for users to call ComputeIndex() directly, to make it more clear that this function
+   * may be expensive.
+   * \sa ComputeIndex */
   const IndexType
   GetIndex() const
   {
-    return m_Image->ComputeIndex(static_cast<OffsetValueType>(m_Offset));
+    return this->ComputeIndex();
   }
 
   /** Set the index. No bounds checking is performed.