A day on Neptune is about 16 hours long, a bit under three-quarters of an Earth day.

Quick Scoop

  • Most sources put a Neptunian day at roughly 16 hours.
  • A more precise modern measurement is about 15 hours 57 minutes 59 seconds for one full rotation.
  • Neptune is a gaseous ice giant, so different latitudes spin at slightly different speeds (the equator vs. the poles), which is why you may see small variations around that 16‑hour figure.

In everyday terms: if you spent one “day” on Neptune, sunrise-to-sunrise would finish in about two-thirds of the time it takes on Earth.

Information gathered from public forums or data available on the internet and portrayed here.