To begin this section, we want to first define measurement and what exactly we will measure in the context of Unreal Engine 4. In a general sense, the definition of measurement is determining the size, length, or the amount of something (such as distance), the length/width/height of an object, or the volume of a particular space. In the context of Unreal Engine 4, we will measure the lengths of each component of a 3D vector in the 3D space and the *X*, *Y*, and *Z* dimensions. For the 2D game world, we will measure the *X* and *Y* axes. In the real world, we can use the U.S. Standard and the European Standard units of measurement to measure distance.

In the U.S., we can use the standard of lengths that involve the use of **inches** (**in**), **feet** (**ft**), **yards** (**yd**), and miles, whereas in Europe, there is the standard of lengths in place that includes **millimeters** (**mm**), **centimeters** (**cm**), **meters** (**m**), and **kilometer** (**km**). For our convenience and as a point of reference, here are a set of conversion charts between the U.S. and the European units of measurements. For more conversions, refer to this free conversion website at http://converter.eu/length/.

The following table shows the U.S. Conversions:

1 ft |
12 in |

1 in |
0.0833333 ft |

1 yd |
3 ft |

1 yd |
36 in |

1 Mile |
1,760 yd |

1 Mile |
5,280 ft |

1 Mile |
63359.999 in |

The following table shows the European Conversions:

1 mm |
0.1 cm |

1 cm |
10 mm |

1 cm |
0.0099999 m |

1 m |
100 cm |

1 m |
1000 mm |

1 mm |
0.000999999 m |

1 km |
1000000 mm |

1 km |
100000 cm |

1 km |
1000 m |

The following table shows U.S. to European Conversions:

1 in |
25.4 mm |

1 in |
2.54 cm |

1 in |
0.0254 m |

1 in |
0.0000254 km |

1 ft |
304.8 mm |

1 ft |
30.48 cm |

1 ft |
0.3048 m |

1 ft |
0.0003048 km |

1 yd |
914.4 mm |

1 yd |
91.44 cm |

1 yd |
0.9144 m |

1 yd |
0.0009144 km |

1 Mile |
1609344 mm |

1 Mile |
160934.4 cm |

1 Mile |
1609.3439999999998 m |

1 Mile |
1.609344 km |

Now that we have a strong understanding of the real-world units of measurement, we are now ready to discuss how Unreal Engine 4 uses these units of measurement to determine distances and sizes of objects.