diff --git a/db/helpers.go b/db/helpers.go
index 7c2237d..05edd65 100644
--- a/db/helpers.go
+++ b/db/helpers.go
@@ -507,6 +507,7 @@ WITH daily AS (
 ), totals AS (
   SELECT COALESCE(SUM(total_samples_day), 0) AS total_samples FROM enriched
 )
+-- monthly averages are weighted by the implied sample counts per day (SamplesPresent / AvgIsPresent)
 INSERT INTO %s (
   "InventoryId", "Name", "Vcenter", "VmId", "EventKey", "CloudId", "CreationTime", "DeletionTime",
   "ResourcePool", "Datacenter", "Cluster", "Folder", "ProvisionedDisk", "VcpuCount",
diff --git a/internal/report/snapshots.go b/internal/report/snapshots.go
index ff23ad4..c0a7b21 100644
--- a/internal/report/snapshots.go
+++ b/internal/report/snapshots.go
@@ -760,7 +760,7 @@ func addTotalsChartSheet(logger *slog.Logger, database db.Database, ctx context.
 		if err != nil || len(records) == 0 {
 			return
 		}
-		points, err := buildDailyTotals(ctx, database.DB(), records)
+		points, err := buildDailyTotals(ctx, database.DB(), records, true)
 		if err != nil || len(points) == 0 {
 			return
 		}
@@ -1042,11 +1042,12 @@ WHERE %s
 			return nil, err
 		}
 		points = append(points, totalsPoint{
-			Label:         record.SnapshotTime.Local().Format("2006-01-02 15:04"),
-			VmCount:       row.VmCount,
-			VcpuTotal:     float64(row.VcpuTotal),
-			RamTotal:      float64(row.RamTotal),
-			PresenceRatio: row.PresenceRatio,
+			Label:     record.SnapshotTime.Local().Format("2006-01-02 15:04"),
+			VmCount:   row.VmCount,
+			VcpuTotal: float64(row.VcpuTotal),
+			RamTotal:  float64(row.RamTotal),
+			// For hourly snapshots, prorated VM count equals VM count (no finer granularity).
+			PresenceRatio: float64(row.VmCount),
 			TinTotal:      row.TinTotal,
 			BronzeTotal:   row.BronzeTotal,
 			SilverTotal:   row.SilverTotal,
@@ -1056,7 +1057,7 @@ WHERE %s
 	return points, nil
 }
 
-func buildDailyTotals(ctx context.Context, dbConn *sqlx.DB, records []SnapshotRecord) ([]totalsPoint, error) {
+func buildDailyTotals(ctx context.Context, dbConn *sqlx.DB, records []SnapshotRecord, prorateByAvg bool) ([]totalsPoint, error) {
 	points := make([]totalsPoint, 0, len(records))
 	for _, record := range records {
 		if err := db.ValidateTableName(record.TableName); err != nil {
@@ -1096,7 +1097,7 @@ WHERE %s
 			VmCount:       row.VmCount,
 			VcpuTotal:     row.VcpuTotal,
 			RamTotal:      row.RamTotal,
-			PresenceRatio: row.PresenceRatio,
+			PresenceRatio: computeProratedVmCount(row.PresenceRatio, row.VmCount, prorateByAvg),
 			TinTotal:      row.TinTotal,
 			BronzeTotal:   row.BronzeTotal,
 			SilverTotal:   row.SilverTotal,
@@ -1106,6 +1107,13 @@ WHERE %s
 	return points, nil
 }
 
+func computeProratedVmCount(presenceRatio float64, vmCount int64, prorate bool) float64 {
+	if !prorate {
+		return float64(vmCount)
+	}
+	return presenceRatio * float64(vmCount)
+}
+
 func writeTotalsChart(logger *slog.Logger, xlsx *excelize.File, sheetName string, points []totalsPoint) {
 	if len(points) == 0 {
 		return
@@ -1162,11 +1170,12 @@ func writeTotalsChart(logger *slog.Logger, xlsx *excelize.File, sheetName string
 			series = append(series, buildSeries(col))
 		}
 		chart := excelize.Chart{
-			Type:   excelize.Line,
-			Series: series,
-			Legend: excelize.ChartLegend{Position: "bottom"},
-			XAxis:  excelize.ChartAxis{MajorGridLines: true},
-			YAxis:  excelize.ChartAxis{MajorGridLines: true},
+			Type:      excelize.Line,
+			Series:    series,
+			Legend:    excelize.ChartLegend{Position: "bottom"},
+			XAxis:     excelize.ChartAxis{MajorGridLines: true},
+			YAxis:     excelize.ChartAxis{MajorGridLines: true},
+			Dimension: excelize.ChartDimension{Width: 960, Height: 480},
 		}
 		if err := xlsx.AddChart(sheetName, anchor, &chart); err != nil {
 			logger.Error("Error adding totals chart", "error", err, "anchor", anchor)
@@ -1174,8 +1183,8 @@ func writeTotalsChart(logger *slog.Logger, xlsx *excelize.File, sheetName string
 	}
 
 	makeChart("K2", "B", "E")
-	makeChart("K18", "C", "D")
-	makeChart("K34", "F", "G", "H", "I")
+	makeChart("K27", "C", "D")
+	makeChart("K52", "F", "G", "H", "I")
 }
 
 func formatEpochHuman(value interface{}) string {