There are an incredibly large number of millimeters in one light-year, far too many to easily comprehend. 5 million millimeters is only 0.0000 light-years.

This is because a light-year is a measure of astronomical distance, covering trillions of kilometers, while 5 million millimeters is only 5 kilometers, a very short distance in comparison.

5,000,000 millimeters is equal to 5 kilometers.

While not for direct practical calculations in everyday life, the conversion is useful for understanding and emphasizing the immense scale of space compared to human-sized measurements.