diff --git a/src/dial.c b/src/dial.c
index 05c1e62..08e5cdc 100644
--- a/src/dial.c
+++ b/src/dial.c
@@ -6,13 +6,15 @@
 #define RAD          (M_PI / 180.0)
 #define ANGLE_OFFSET (M_PI / 2.0)
 
-#define DIAL_MAIN_BEZEL_WIDTH 16
+#define DIAL_MAIN_BEZEL_WIDTH (16.0 / 240.0)
 
 #define DIAL_RADIUS_LEGEND_MAIN   0.69
 #define DIAL_RADIUS_LEGEND_BOTTOM 0.725
 
-#define DIAL_RADIUS_NEEDLE_MAIN_MIN 0.51
-#define DIAL_RADIUS_NEEDLE_MAIN_MAX 0.89
+#define DIAL_NEEDLE_WIDTH (8.0 / 240.0)
+
+#define DIAL_RADIUS_NEEDLE_MAIN_MIN  0.51
+#define DIAL_RADIUS_NEEDLE_MAIN_MAX  0.89
 
 #define DIAL_RADIUS_NEEDLE_BOTTOM_MIN 0.8
 #define DIAL_RADIUS_NEEDLE_BOTTOM_MAX 0.9
@@ -68,7 +70,7 @@ static int main_draw_bg(hexagram_gauge *gauge, cairo_t *cr) {
     double arc[5] = {
         dial->gauge.x,
         dial->gauge.y,
-        dial->radius - DIAL_MAIN_BEZEL_WIDTH,
+        dial->radius - (dial->radius * DIAL_MAIN_BEZEL_WIDTH),
         0,
         2.0 * M_PI
     };
@@ -80,13 +82,13 @@ static int main_draw_bg(hexagram_gauge *gauge, cairo_t *cr) {
 
     /* Gauge bezel */
     cairo_set_source(cr, dial->gradient);
-    cairo_set_line_width(cr, DIAL_MAIN_BEZEL_WIDTH);
+    cairo_set_line_width(cr, dial->radius * DIAL_MAIN_BEZEL_WIDTH);
     cairo_arc(cr, arc[0], arc[1], arc[2], arc[3], arc[4]);
     cairo_stroke(cr);
 
     /* Gauge centre bezel */
     cairo_set_source_rgba(cr, 1, 1, 1, gauge->alpha);
-    cairo_set_line_width(cr, DIAL_MAIN_BEZEL_WIDTH / 3.0);
+    cairo_set_line_width(cr, dial->radius * DIAL_MAIN_BEZEL_WIDTH / 3.0);
     cairo_arc(cr, dial->gauge.x, dial->gauge.y, dial->radius / 2, 0, 2.0 * M_PI);
     cairo_stroke(cr);
 
@@ -117,7 +119,7 @@ static int main_draw_fg(hexagram_gauge *gauge, cairo_t *cr) {
 static int bottom_draw_bg(hexagram_gauge *gauge, cairo_t *cr) {
     hexagram_dial *dial = (hexagram_dial *)gauge;
 
-    cairo_set_line_width(cr, 24);
+    cairo_set_line_width(cr, dial->radius * (24 / 240.0));
     cairo_set_source_rgba(cr, 0.2, 0.2, 0.2, gauge->alpha);
 
     cairo_arc(cr,
@@ -281,7 +283,7 @@ int hexagram_dial_draw_needle(hexagram_dial *dial, cairo_t *cr, double value) {
     }
 
     cairo_set_source_rgba(cr, 1, 0.4, 1, 0.75 * dial->gauge.alpha);
-    cairo_set_line_width(cr, 8);
+    cairo_set_line_width(cr, dial->radius * DIAL_NEEDLE_WIDTH);
 
     cairo_move_to(cr,
                   dial->gauge.x + min_radius * dial->radius * cos(angle),
diff --git a/src/fuel.c b/src/fuel.c
index 345f20e..8e6700d 100644
--- a/src/fuel.c
+++ b/src/fuel.c
@@ -4,6 +4,8 @@
 #include <hexagram/gauge.h>
 #include <hexagram/fuel.h>
 
+#define MARK_WIDTH (6.0 / 240.0)
+
 #define RAD (M_PI / 180.0)
 
 #define LEVEL_MIN   0
@@ -36,7 +38,7 @@ static int draw_bg(hexagram_gauge *gauge, cairo_t *cr) {
     cairo_set_source_rgba(cr, 1, 1, 1, gauge->alpha);
     hexagram_dial_draw_legend(&fuel->dial, cr, fuel->dial.max_value, "1");
 
-    cairo_set_line_width(cr, 6.0);
+    cairo_set_line_width(cr, fuel->dial.radius * MARK_WIDTH);
 
     for (level=0; level<=LEVEL_MAX; level++) {
         int large = 0;
diff --git a/src/speedo.c b/src/speedo.c
index 5ebd278..45dfada 100644
--- a/src/speedo.c
+++ b/src/speedo.c
@@ -6,6 +6,9 @@
 
 #define SPEED_FACTOR_MPH 0.621371
 
+#define MARK_WIDTH_LARGE (6.0 / 240.0)
+#define MARK_WIDTH       (2.0 / 240.0)
+
 #define ANGLE_MIN 232.0 * (M_PI / 180.0)
 #define ANGLE_MAX 488.0 * (M_PI / 180.0)
 
@@ -64,7 +67,7 @@ static int draw_bg(hexagram_gauge *gauge, cairo_t *cr) {
     for (speed=0; speed<=max; speed += 5) {
         int large = speed % 10 == 0? 1: 0;
 
-        cairo_set_line_width(cr, large? 6.0: 2.0);
+        cairo_set_line_width(cr, speedo->dial.radius * (large? MARK_WIDTH_LARGE: MARK_WIDTH));
         hexagram_dial_draw_mark(&speedo->dial, cr, (double)speed / factor, large);
     }
 
diff --git a/src/tacho.c b/src/tacho.c
index 59f8f8f..c753dd3 100644
--- a/src/tacho.c
+++ b/src/tacho.c
@@ -4,6 +4,9 @@
 #include <hexagram/gauge.h>
 #include <hexagram/tacho.h>
 
+#define MARK_WIDTH_LARGE (6.0 / 240.0)
+#define MARK_WIDTH       (2.0 / 240.0)
+
 #define ANGLE_MIN (232.0 * (M_PI / 180.0))
 #define ANGLE_MAX (488.0 * (M_PI / 180.0))
 
@@ -36,7 +39,7 @@ static int draw_bg(hexagram_gauge *gauge, cairo_t *cr) {
             cairo_set_source_rgba(cr, 0.6, 0.1, 0.1, gauge->alpha);
         }
 
-        cairo_set_line_width(cr, large? 6.0: 2.0);
+        cairo_set_line_width(cr, tacho->dial.radius * (large? MARK_WIDTH_LARGE: MARK_WIDTH));
 
         hexagram_dial_draw_mark(&tacho->dial, cr, rpm, large);
     }
diff --git a/src/thermo.c b/src/thermo.c
index 899f247..93fa2f4 100644
--- a/src/thermo.c
+++ b/src/thermo.c
@@ -3,6 +3,8 @@
 #include <hexagram/gauge.h>
 #include <hexagram/thermo.h>
 
+#define MARK_WIDTH (6.0 / 240.0)
+
 #define RAD (M_PI / 180.0)
 
 #define ANGLE_MIN (144.0 * RAD)
@@ -36,7 +38,7 @@ static int draw_bg(hexagram_gauge *gauge, cairo_t *cr) {
     cairo_set_source_rgba(cr, 1, 0, 0, gauge->alpha);
     hexagram_dial_draw_legend(&thermo->dial, cr, thermo->dial.max_value, "H");
 
-    cairo_set_line_width(cr, 6.0);
+    cairo_set_line_width(cr, thermo->dial.radius * MARK_WIDTH);
 
     incr = (thermo->dial.max_value - thermo->dial.min_value) / 8.0;