diff --git a/software/gui.py b/software/gui.py
index c4e21c9..2566aac 100644
--- a/software/gui.py
+++ b/software/gui.py
@@ -641,7 +641,7 @@ class MainWindow(QMainWindow):
     def setup_graph(self):
         self.graph_widget = pg.PlotWidget()
         self.graph_widget.setLabel("left", "ADC value")
-        self.graph_widget.setLabel("bottom", "Sample")
+        self.graph_widget.setLabel("bottom", "Distance", units="km")
         self.graph_widget.showGrid(x=True, y=True)
 
         self.graph_curve = self.graph_widget.plot(
@@ -784,7 +784,18 @@ class MainWindow(QMainWindow):
             self.graph_curve.setData([])
             return
 
-        x = list(range(len(self.data)))
+        LS = 200000  # km/s
+
+        period_us = self.pulse_period / self.dac_clk
+        max_distance_km = LS * period_us / 10e6
+
+        sample_count = len(self.data)
+
+        x = [
+            i * max_distance_km / sample_count
+            for i in range(sample_count)
+        ]
+
         self.graph_curve.setData(x, self.data)
 
     def update_reference_graph(self):