diff --git a/capture/src/sink.rs b/capture/src/sink.rs
index 724f47c..c1d291a 100644
--- a/capture/src/sink.rs
+++ b/capture/src/sink.rs
@@ -240,6 +240,7 @@ impl EventSink for KafkaSink {
         let limited = self.partition.is_limited(&event.key());
         let ack =
             Self::kafka_send(self.producer.clone(), self.topic.clone(), event, limited).await?;
+        histogram!("capture_event_batch_size", 1.0);
         Self::process_ack(ack).await
     }