165 Earth years, or roughly 60,266 Earth days.

hmm...precisley...1/2 days.... any of u begg to differ? i dont think so.

According to NASA it takes 60,190 Earth days to complete one orbit. http://solarsystem.nasa.gov/planets/profile.cfm?Object=Neptune&Display=Facts

164.8 Years* (60,189 Days) * The approximation of 365.256 days per year is used. http://library.thinkquest.org/C005921/Neptune/neptLocOrb.htm Neptune is about 30 times farther from the sun than the Earth is; it averages 30.06 A.U. from the sun. Occasionally, Neptune's orbit is actually outside that of Pluto; this is because of Pluto's highly eccentric (non-circular) orbit. During this time (20 years out of every 248 Earth years), Neptune is actually the farthest planet from the Sun (and not Pluto). From January 21, 1979 until February 11, 1999, Pluto was inside the orbit of Neptune. Now and until September 2226, Pluto is outside the orbit of Neptune. http://www.enchantedlearning.com/subjects/astronomy/planets/neptune/ Neptune is the eighth planet from the Sun; the only planet farther from the Sun is Pluto. Every 248 years, Pluto travels inside Neptune's orbit for about a 20 year period, during which it is nearer the Sun than Neptune. Pluto entered Neptune's orbit in January, 1979, and stayed there until March, 1999. The orbit of Neptune, called the blue planet, is 4,504,000,000 kilometers from the the Sun, about 30 times as far from the Sun as the Earth. Neptune's rotation period as it spins on its axis, in earth hours, is 16.11 hours, compared to our 24 hour rotation periods. Neptune's axis is tilted 30 degrees to the Sun's orbit. Neptune moves around the Sun in an elliptical or oval-shaped orbit; its orbit period in earth years is 163.72 years. One season on Neptune lasts for forty years; its south pole is in darkness for forty years, while the north pole is in sunlight for forty years. Being the smallest gas planet, Neptune's diameter of 49,500 km is smaller than Jupiter's and Uranus', but is larger than the Earth's (almost 4 times the Earth's). http://www.edu.pe.ca/southernkings/Neptune.htm