diff --git a/python/cudf_polars/cudf_polars/streaming/actor_graph/io.py b/python/cudf_polars/cudf_polars/streaming/actor_graph/io.py
index 822a84d38c75..5e5cf8ee12b1 100644
--- a/python/cudf_polars/cudf_polars/streaming/actor_graph/io.py
+++ b/python/cudf_polars/cudf_polars/streaming/actor_graph/io.py
@@ -606,7 +606,9 @@ def _(
                 rec.state["ir_context"],
                 ch_out,
                 num_producers=num_producers,
-                estimated_chunk_bytes=executor.target_partition_size,
+                estimated_chunk_bytes=(
+                    plan.estimated_chunk_bytes or executor.target_partition_size
+                ),
             )
         ]
     return nodes, channels
diff --git a/python/cudf_polars/cudf_polars/streaming/base.py b/python/cudf_polars/cudf_polars/streaming/base.py
index 9415c1d245a1..880393f08619 100644
--- a/python/cudf_polars/cudf_polars/streaming/base.py
+++ b/python/cudf_polars/cudf_polars/streaming/base.py
@@ -166,12 +166,21 @@ class IOPartitionPlan:
       - SINGLE_READ: `factor` is the total number of files.
     """
 
-    __slots__ = ("factor", "flavor")
+    __slots__ = ("estimated_chunk_bytes", "factor", "flavor")
     factor: int
     flavor: IOPartitionFlavor
+    estimated_chunk_bytes: int | None
+    """Estimated decompressed bytes per chunk (Scan nodes only)."""
 
-    def __init__(self, factor: int, flavor: IOPartitionFlavor) -> None:
+    def __init__(
+        self,
+        factor: int,
+        flavor: IOPartitionFlavor,
+        *,
+        estimated_chunk_bytes: int | None = None,
+    ) -> None:
         if flavor == IOPartitionFlavor.SINGLE_FILE and factor != 1:  # pragma: no cover
             raise ValueError(f"Expected factor == 1 for {flavor}, got: {factor}")
         self.factor = factor
         self.flavor = flavor
+        self.estimated_chunk_bytes = estimated_chunk_bytes
diff --git a/python/cudf_polars/cudf_polars/streaming/io.py b/python/cudf_polars/cudf_polars/streaming/io.py
index d56c31ce379b..da781fbd8051 100644
--- a/python/cudf_polars/cudf_polars/streaming/io.py
+++ b/python/cudf_polars/cudf_polars/streaming/io.py
@@ -90,15 +90,19 @@ def scan_partition_plan(
             if (file_size := sum(column_sizes)) > 0:
                 if file_size > blocksize:
                     # Split large files
+                    factor = math.ceil(file_size / blocksize)
                     return IOPartitionPlan(
-                        math.ceil(file_size / blocksize),
+                        factor,
                         IOPartitionFlavor.SPLIT_FILES,
+                        estimated_chunk_bytes=file_size // factor,
                     )
                 else:
                     # Fuse small files
+                    factor = max(blocksize // int(file_size), 1)
                     return IOPartitionPlan(
-                        max(blocksize // int(file_size), 1),
+                        factor,
                         IOPartitionFlavor.FUSED_FILES,
+                        estimated_chunk_bytes=file_size * factor,
                     )
 
     # TODO: Use file sizes for csv and json