diff --git a/urdf/inertial_macros.xacro b/urdf/inertial_macros.xacro
index e69de29..5cf1cac 100644
--- a/urdf/inertial_macros.xacro
+++ b/urdf/inertial_macros.xacro
@@ -0,0 +1,40 @@
+<?xml version="1.0"?>
+<robot xmlns:xacro="http://www.ros.org/wiki/xacro" >
+
+    <!-- Specify some standard inertial calculations https://en.wikipedia.org/wiki/List_of_moments_of_inertia -->
+    <!-- These make use of xacro's mathematical functionality -->
+
+    <xacro:macro name="inertial_sphere" params="mass radius *origin">
+        <inertial>
+            <xacro:insert_block name="origin"/>
+            <mass value="${mass}" />
+            <inertia ixx="${(2/5) * mass * (radius*radius)}" ixy="0.0" ixz="0.0"
+                    iyy="${(2/5) * mass * (radius*radius)}" iyz="0.0"
+                    izz="${(2/5) * mass * (radius*radius)}" />
+        </inertial>
+    </xacro:macro>  
+
+
+    <xacro:macro name="inertial_box" params="mass x y z *origin">
+        <inertial>
+            <xacro:insert_block name="origin"/>
+            <mass value="${mass}" />
+            <inertia ixx="${(1/12) * mass * (y*y+z*z)}" ixy="0.0" ixz="0.0"
+                    iyy="${(1/12) * mass * (x*x+z*z)}" iyz="0.0"
+                    izz="${(1/12) * mass * (x*x+y*y)}" />
+        </inertial>
+    </xacro:macro>
+
+
+    <xacro:macro name="inertial_cylinder" params="mass length radius *origin">
+        <inertial>
+            <xacro:insert_block name="origin"/>
+            <mass value="${mass}" />
+            <inertia ixx="${(1/12) * mass * (3*radius*radius + length*length)}" ixy="0.0" ixz="0.0"
+                    iyy="${(1/12) * mass * (3*radius*radius + length*length)}" iyz="0.0"
+                    izz="${(1/2) * mass * (radius*radius)}" />
+        </inertial>
+    </xacro:macro>
+
+
+</robot>
\ No newline at end of file