diff --git a/weed/server/master_grpc_server_volume.go b/weed/server/master_grpc_server_volume.go
index 184a6c214..287706821 100644
--- a/weed/server/master_grpc_server_volume.go
+++ b/weed/server/master_grpc_server_volume.go
@@ -204,20 +204,9 @@ func (ms *MasterServer) Statistics(ctx context.Context, req *master_pb.Statistic
 		return nil, raft.NotLeaderError
 	}
 
-	if req.Replication == "" {
-		req.Replication = ms.option.DefaultReplicaPlacement
-	}
-	replicaPlacement, err := super_block.NewReplicaPlacementFromString(req.Replication)
-	if err != nil {
-		return nil, err
-	}
-	ttl, err := needle.ReadTTL(req.Ttl)
-	if err != nil {
-		return nil, err
-	}
-
-	volumeLayout := ms.Topo.GetVolumeLayout(req.Collection, replicaPlacement, ttl, types.ToDiskType(req.DiskType))
-	stats := volumeLayout.Stats()
+	// an empty collection means all collections, and a named collection covers
+	// all its layouts, so used size matches the topology-wide total size below
+	stats := ms.Topo.CollectionVolumeStats(req.Collection)
 	totalSize := ms.Topo.GetDiskUsages().GetMaxVolumeCount() * int64(ms.option.VolumeSizeLimitMB) * 1024 * 1024
 	resp := &master_pb.StatisticsResponse{
 		TotalSize: uint64(totalSize),
diff --git a/weed/topology/topology.go b/weed/topology/topology.go
index ddba44d2d..4b2adb988 100644
--- a/weed/topology/topology.go
+++ b/weed/topology/topology.go
@@ -431,6 +431,29 @@ func (t *Topology) GetVolumeLayout(collectionName string, rp *super_block.Replic
 	}).(*Collection).GetOrCreateVolumeLayout(rp, ttl, diskType)
 }
 
+// CollectionVolumeStats aggregates stats across all volume layouts of one
+// collection, or across every collection when collectionName is empty.
+func (t *Topology) CollectionVolumeStats(collectionName string) *VolumeLayoutStats {
+	ret := &VolumeLayoutStats{}
+	var collections []*Collection
+	if collectionName == "" {
+		for _, c := range t.collectionMap.Items() {
+			collections = append(collections, c.(*Collection))
+		}
+	} else if c, found := t.FindCollection(collectionName); found {
+		collections = append(collections, c)
+	}
+	for _, c := range collections {
+		for _, vl := range c.GetAllVolumeLayouts() {
+			stats := vl.Stats()
+			ret.TotalSize += stats.TotalSize
+			ret.UsedSize += stats.UsedSize
+			ret.FileCount += stats.FileCount
+		}
+	}
+	return ret
+}
+
 func (t *Topology) ListCollections(includeNormalVolumes, includeEcVolumes bool) (ret []string) {
 	found := make(map[string]bool)
 
diff --git a/weed/topology/topology_stats_test.go b/weed/topology/topology_stats_test.go
new file mode 100644
index 000000000..2c17ab684
--- /dev/null
+++ b/weed/topology/topology_stats_test.go
@@ -0,0 +1,47 @@
+package topology
+
+import (
+	"testing"
+	"time"
+
+	"github.com/seaweedfs/seaweedfs/weed/pb/master_pb"
+	"github.com/seaweedfs/seaweedfs/weed/sequence"
+	"github.com/seaweedfs/seaweedfs/weed/storage/needle"
+)
+
+func TestCollectionVolumeStats(t *testing.T) {
+	topo := NewTopology("weedfs", sequence.NewMemorySequencer(), 32*1024, 5, false)
+
+	dc := topo.GetOrCreateDataCenter("dc1")
+	rack := dc.GetOrCreateRack("rack1")
+	maxVolumeCounts := map[string]uint32{"": 25, "ssd": 12}
+	dn := rack.GetOrCreateDataNode("127.0.0.1", 34534, 0, "127.0.0.1", "", maxVolumeCounts)
+
+	volumeMessages := []*master_pb.VolumeInformationMessage{
+		{Id: 1, Size: 1000, Collection: "", FileCount: 10, ReplicaPlacement: 0, Version: uint32(needle.GetCurrentVersion())},
+		{Id: 2, Size: 2000, Collection: "c1", FileCount: 20, ReplicaPlacement: 0, Version: uint32(needle.GetCurrentVersion())},
+		{Id: 3, Size: 3000, Collection: "c1", FileCount: 30, ReplicaPlacement: 0, Version: uint32(needle.GetCurrentVersion()), DiskType: "ssd"},
+		{Id: 4, Size: 4000, Collection: "c2", FileCount: 40, ReplicaPlacement: 1, Version: uint32(needle.GetCurrentVersion())},
+	}
+	topo.SyncDataNodeRegistration(volumeMessages, dn)
+
+	// VolumeLocationList.Stats only counts nodes connected for over a minute
+	dn.LastSeen = time.Now().Unix() - 61
+
+	allStats := topo.CollectionVolumeStats("")
+	assert(t, "all collections used size", int(allStats.UsedSize), 10000)
+	assert(t, "all collections file count", int(allStats.FileCount), 100)
+
+	c1Stats := topo.CollectionVolumeStats("c1")
+	assert(t, "c1 used size across disk types", int(c1Stats.UsedSize), 5000)
+	assert(t, "c1 file count", int(c1Stats.FileCount), 50)
+
+	c2Stats := topo.CollectionVolumeStats("c2")
+	assert(t, "c2 used size", int(c2Stats.UsedSize), 4000)
+
+	missingStats := topo.CollectionVolumeStats("no-such-collection")
+	assert(t, "missing collection used size", int(missingStats.UsedSize), 0)
+	if _, found := topo.FindCollection("no-such-collection"); found {
+		t.Errorf("stats query should not create a phantom collection")
+	}
+}