Neptune is approximately 4.5 billion kilometers (about 2.8 billion miles) away from the Sun on average. This distance is about 30 astronomical units (AU), where 1 AU is the average distance from the Earth to the Sun (about 149.6 million kilometers)

. Because Neptune's orbit is elliptical, its distance from the Sun varies slightly:

• At its closest (perihelion), Neptune is about 4.46 billion km (2.77 billion miles) from the Sun.
• At its farthest (aphelion), it is about 4.54 billion km (2.82 billion miles) away

Neptune takes about 165 Earth years to complete one orbit around the Sun at this distance