A full moon occurs about once every 29.5 days , which is the length of the lunar (synodic) month.

Quick Scoop

  • On average, you see 12 full moons per year , spaced roughly 29–30 days apart.
  • Roughly every 2–3 years , a year has 13 full moons , and the extra one is often called a “blue moon.”

Why every ~29.5 days?

The Moon orbits Earth and cycles through all its phases (new → full → new again) in about 29.5 days , which is why full moons repeat on a monthly rhythm , not on a strict calendar‑month pattern.

  • That 0.5‑day “leftover” is why the full‑moon date shifts earlier in the calendar each month.
  • Because Earth’s year is 365.25 days , the mismatch between the lunar cycle and our calendar is what creates occasional 13‑full‑moon years.

How many full moons in a year?

Most years have 12 full moons , but some have 13 , depending on how the 29.5‑day cycle lines up with the calendar.

Situation| Approximate frequency
---|---
12 full moons in a year| Most common; happens in many years (e.g., 2025). 78
13 full moons in a year| Roughly every 2–3 years ; the extra one is a “blue moon.” 1710

What it looks like in practice

To your eyes, the Moon often appears full for about 2–3 days around the exact full‑moon instant, even though the precise “full” moment is just a single point in time.

  • In 2026 , for example, full moons fall on dates like February 1, March 3, April 1, May 1, May 31 (blue moon), June 29 , and so on, spaced about 29–30 days apart.

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