diff --git a/fs/zfs/stats.go b/fs/zfs/stats.go
index b41a9f82e7..a2a2d5454a 100644
--- a/fs/zfs/stats.go
+++ b/fs/zfs/stats.go
@@ -25,7 +25,11 @@ func GetZfsStats(poolName string) (uint64, uint64, uint64, error) {
 		return 0, 0, 0, err
 	}
 
-	total := dataset.Used + dataset.Avail + dataset.Usedbydataset
+	total := zfsCapacity(dataset)
 
 	return total, dataset.Avail, dataset.Avail, nil
 }
+
+func zfsCapacity(dataset *zfslib.Dataset) uint64 {
+	return dataset.Used + dataset.Avail
+}
diff --git a/fs/zfs/stats_test.go b/fs/zfs/stats_test.go
new file mode 100644
index 0000000000..56df274a2c
--- /dev/null
+++ b/fs/zfs/stats_test.go
@@ -0,0 +1,33 @@
+// Copyright 2026 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package zfs
+
+import (
+	"testing"
+
+	zfslib "github.com/mistifyio/go-zfs"
+)
+
+func TestZfsCapacityDoesNotDoubleCountUsedbydataset(t *testing.T) {
+	dataset := &zfslib.Dataset{
+		Used:          25,
+		Avail:         75,
+		Usedbydataset: 10,
+	}
+
+	if got, want := zfsCapacity(dataset), uint64(100); got != want {
+		t.Fatalf("zfsCapacity() = %d, want %d", got, want)
+	}
+}