When is the next full moon?

UmbraLux calculates every date and time on this page itself, with the astronomy library astronomy-engine – the same calculation the UmbraLux app uses for its charts. As usual in astrology, positions are measured in the tropical zodiac: the signs start at the vernal equinox and span 30° each.

New moon, first quarter, full moon and last quarter are the moments when the Moon stands 0°, 90°, 180° or 270° east of the Sun, measured by the apparent positions of Sun and Moon – as the astronomical almanacs define them. The Moon changes sign when it crosses into the next zodiac sign, about every two and a half days.

An automated test compares our times for 2026 and 2027 with published values: all 99 moon phases lie within one minute of NASA JPL Horizons, and it checks them against the US Naval Observatory's tables too. The 24 moon sign changes it checks (one a month) lie within one minute of JPL Horizons.

On average the full moon returns every 29.5 days (a synodic month). Because the Moon's orbit is an ellipse, the gap varies: between the full moons of 2026 and 2027 there are 29.4 to 29.7 days.

So a calendar year holds twelve or thirteen full moons: 2026 has 13, 2027 has 12.

At full moon the Moon stands exactly opposite the Sun, so always in the sign opposite the current Sun sign: with the Sun in Libra, the full moon is in Aries. Astrology reads the full moon as the peak of a lunar cycle, a time when what began at the new moon shows itself.