diff --git a/tools/rw-heatmaps/pkg/chart/line_chart.go b/tools/rw-heatmaps/pkg/chart/line_chart.go
index 2415793e09c..a9964bfe21d 100644
--- a/tools/rw-heatmaps/pkg/chart/line_chart.go
+++ b/tools/rw-heatmaps/pkg/chart/line_chart.go
@@ -1,4 +1,4 @@
-// Copyright 2024 The etcd Authors
+// Copyright 2025 The etcd Authors
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -56,8 +56,9 @@ func plotLineChart(datasets []*dataset.DataSet, title string) *vgimg.Canvas {
 		return len(max.GetSortedRatios())
 	}()
 
-	// Make a nx1 grid of heatmaps.
-	rows, cols := ratiosLength, 1
+	// Make a nx1 grid of line charts.
+	const cols = 1
+	rows := ratiosLength
 
 	// Set the width and height of the canvas.
 	width, height := 30*vg.Centimeter, 15*font.Length(ratiosLength)*vg.Centimeter
@@ -78,10 +79,9 @@ func plotLineChart(datasets []*dataset.DataSet, title string) *vgimg.Canvas {
 	}
 
 	plots := make([][]*plot.Plot, rows)
-	legends := make([][]plot.Legend, rows)
+	legends := make([]plot.Legend, rows)
 	for i := range plots {
 		plots[i] = make([]*plot.Plot, cols)
-		legends[i] = make([]plot.Legend, cols)
 	}
 
 	// Load records into the grid.
@@ -89,8 +89,7 @@ func plotLineChart(datasets []*dataset.DataSet, title string) *vgimg.Canvas {
 		return cmp.Compare(len(a.GetSortedRatios()), len(b.GetSortedRatios()))
 	}).GetSortedRatios()
 
-	row, col := 0, 0
-	for _, ratio := range ratios {
+	for row, ratio := range ratios {
 		var records [][]dataset.DataRecord
 		var fileNames []string
 		for _, d := range datasets {
@@ -98,34 +97,27 @@ func plotLineChart(datasets []*dataset.DataSet, title string) *vgimg.Canvas {
 			fileNames = append(fileNames, d.FileName)
 		}
 		p, l := plotIndividualLineChart(fmt.Sprintf("R/W Ratio %0.04f", ratio), records, fileNames)
-		plots[row][col] = p
-		legends[row][col] = l
-
-		if col++; col == cols {
-			col = 0
-			row++
-		}
+		plots[row] = []*plot.Plot{p}
+		legends[row] = l
 	}
 
 	// Fill the canvas with the plots and legends.
 	canvases := plot.Align(plots, t, dc)
 	for i := 0; i < rows; i++ {
-		for j := 0; j < cols; j++ {
-			// Continue if there is no plot in the current cell (incomplete data).
-			if plots[i][j] == nil {
-				continue
-			}
-
-			l := legends[i][j]
-			r := l.Rectangle(canvases[i][j])
-			legendWidth := r.Max.X - r.Min.X
-			// Adjust the legend down a little.
-			l.YOffs = plots[i][j].Title.TextStyle.FontExtents().Height * 3
-			l.Draw(canvases[i][j])
-
-			c := draw.Crop(canvases[i][j], 0, -legendWidth-vg.Millimeter, 0, 0)
-			plots[i][j].Draw(c)
+		// Continue if there is no plot in the current cell (incomplete data).
+		if plots[i][0] == nil {
+			continue
 		}
+
+		l := legends[i]
+		r := l.Rectangle(canvases[i][cols])
+		legendWidth := r.Max.X - r.Min.X
+		// Adjust the legend down a little.
+		l.YOffs = plots[i][0].Title.TextStyle.FontExtents().Height * 3
+		l.Draw(canvases[i][0])
+
+		c := draw.Crop(canvases[i][cols], 0, -legendWidth-vg.Millimeter, 0, 0)
+		plots[i][0].Draw(c)
 	}
 
 	// Add the title and parameter legend.