diff --git a/src/common/src/row/mod.rs b/src/common/src/row/mod.rs
index 6cd43e7d25b89..ce2f9e2744996 100644
--- a/src/common/src/row/mod.rs
+++ b/src/common/src/row/mod.rs
@@ -78,7 +78,11 @@ pub trait Row: Sized + std::fmt::Debug + PartialEq + Eq {
     /// Serializes the row with value encoding and returns the bytes.
     #[inline]
     fn value_serialize(&self) -> Vec<u8> {
-        let mut buf = Vec::with_capacity(self.len()); // each datum is at least 1 byte
+        let estimate_size = self
+            .iter()
+            .map(value_encoding::estimate_serialize_datum_size)
+            .sum();
+        let mut buf = Vec::with_capacity(estimate_size);
         self.value_serialize_into(&mut buf);
         buf
     }
@@ -86,7 +90,11 @@ pub trait Row: Sized + std::fmt::Debug + PartialEq + Eq {
     /// Serializes the row with value encoding and returns the bytes.
     #[inline]
     fn value_serialize_bytes(&self) -> Bytes {
-        let mut buf = BytesMut::with_capacity(self.len()); // each datum is at least 1 byte
+        let estimate_size = self
+            .iter()
+            .map(value_encoding::estimate_serialize_datum_size)
+            .sum();
+        let mut buf = BytesMut::with_capacity(estimate_size);
         self.value_serialize_into(&mut buf);
         buf.freeze()
     }