diff --git a/src/kiri/print.js b/src/kiri/print.js
index 5688c2b3..969ddb04 100644
--- a/src/kiri/print.js
+++ b/src/kiri/print.js
@@ -114,6 +114,7 @@
             seq = [],
             abs = true,
             move = false,
+            factor = 1,
             tool = 0,
             E0G0 = false,
             G0 = function() {
@@ -154,6 +155,12 @@
                 }
             }
             switch (cmd) {
+                case 'G20':
+                    factor = 25.4;
+                    break;
+                case 'G21':
+                    factor = 1;
+                    break;
                 case 'G90':
                     // absolute positioning
                     abs = true;
@@ -168,12 +175,12 @@
                     line.forEach(function(tok) {
                         pos[tok.charAt(0)] = parseFloat(tok.substring(1));
                     });
-                    if (pos.X) bounds.min.x = Math.min(bounds.min.x, pos.X);
-                    if (pos.X) bounds.max.x = Math.max(bounds.max.x, pos.X);
-                    if (pos.Y) bounds.min.y = Math.min(bounds.min.y, pos.Y);
-                    if (pos.Y) bounds.max.y = Math.max(bounds.max.y, pos.Y);
-                    if (pos.Z) bounds.min.z = Math.min(bounds.min.z, pos.Z);
-                    if (pos.Z) bounds.max.z = Math.max(bounds.max.z, pos.Z);
+                    if (pos.X) bounds.min.x = Math.min(bounds.min.x, pos.X * factor);
+                    if (pos.X) bounds.max.x = Math.max(bounds.max.x, pos.X * factor);
+                    if (pos.Y) bounds.min.y = Math.min(bounds.min.y, pos.Y * factor);
+                    if (pos.Y) bounds.max.y = Math.max(bounds.max.y, pos.Y * factor);
+                    if (pos.Z) bounds.min.z = Math.min(bounds.min.z, pos.Z * factor);
+                    if (pos.Z) bounds.max.z = Math.max(bounds.max.z, pos.Z * factor);
                     if (pos.E) E0G0 = true;
                     if (E0G0 && pos.E === 0.0) {
                         if (LZ != pos.Z) G0();
@@ -182,9 +189,9 @@
                     addOutput(
                         seq,
                         {
-                            x:pos.X + off.X + xoff.X,
-                            y:pos.Y + off.Y + xoff.Y,
-                            z:pos.Z + off.Z + xoff.Z
+                            x:(factor * pos.X + off.X + xoff.X),
+                            y:(factor * pos.Y + off.Y + xoff.Y),
+                            z:(factor * pos.Z + off.Z + xoff.Z)
                         },
                         !move,
                         pos.F,
diff --git a/src/mode/cam/driver.js b/src/mode/cam/driver.js
index 4a91ea57..a66c15d8 100644
--- a/src/mode/cam/driver.js
+++ b/src/mode/cam/driver.js
@@ -1834,6 +1834,7 @@
             time = 0,
             lines = 0,
             bytes = 0,
+            factor = 1,
             output = [],
             spindle = 0,
             modes = CPRO,
@@ -1911,6 +1912,11 @@
                     line = line.substring(0, cidx).trim();
                     if (line.length === 0) continue;
                 }
+                if (line.indexOf('G20') === 0) {
+                    factor = 1/25.4;
+                } else if (line.indexOf('G21') === 0) {
+                    factor = 1;
+                }
                 append(line);
             }
         }
@@ -1921,7 +1927,7 @@
             if (d < 0) {
                 return s + '.0';
             } else {
-                return s;
+                return val.toFixed(decimals);
             }
         }
 
@@ -2000,19 +2006,19 @@
                 pos.x = newpos.x;
                 runbox.min.x = Math.min(runbox.min.x, pos.x);
                 runbox.max.x = Math.max(runbox.max.x, pos.x);
-                nl.append(space).append("X").append(add0(pos.x));
+                nl.append(space).append("X").append(add0(pos.x * factor));
             }
             if (newpos.y !== pos.y) {
                 pos.y = newpos.y;
                 runbox.min.y = Math.min(runbox.min.y, pos.y);
                 runbox.max.y = Math.max(runbox.max.y, pos.y);
-                nl.append(space).append("Y").append(add0(pos.y));
+                nl.append(space).append("Y").append(add0(pos.y * factor));
             }
             if (newpos.z !== pos.z) {
                 pos.z = newpos.z;
                 runbox.min.z = Math.min(runbox.min.z, pos.z);
                 runbox.max.z = Math.max(runbox.max.z, pos.z);
-                nl.append(space).append("Z").append(add0(pos.z));
+                nl.append(space).append("Z").append(add0(pos.z * factor));
             }
             if (feed && feed !== pos.f) {
                 pos.f = feed;