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MOON & BIRTH CHARTS

Birth Moon Phase Calculator

Enter the recorded local birth date and clock time with the UTC offset that applied then. The browser calculates the Moon’s angle from the Sun and places it in an eight-part cycle.

STAR & SIGIL

Your birth chart awaits

Open Birth Chart

Find the phase at birth

Use the local clock date from the birth record. The offset must match that date and place; an atlas can help you check older time-zone rules.

The fixed UTC offset is used across the entire entered local date; check dates when a civil clock changed. Exact phase boundaries can occur between the two date-only endpoint samples.

How to read the answer

The angle begins at zero when the Sun and Moon have the same geocentric tropical ecliptic longitude. It grows toward 90° at the first quarter, 180° at full, and 270° at the last quarter. Subtracting the Sun's longitude from the Moon's and wrapping the result into 0°–360° gives the displayed angle. Each of the eight labels covers a 45° interval.

This angular definition lets a birth chart answer a focused question. A full Moon need not look exactly full from every place at the very same local clock time; the astronomical event is defined independently of local horizon visibility. A phase label alone is also a narrow astrological reading. The Moon's sign, houses, aspects, and the quality of the birth record change the wider chart context.

Read the eight-phase guide and the birth-time caveats, or use the Moon phase calendar for the next exact new, quarter, and full Moon events.