On average, 29 1/2 days.
7 days
The full lunar cycle is roughly 4 weeks, and from full-moon to new-moon is half the cycle, so it would take (roughly) 2 weeks to go from full to new moon.
The cycle of the moon's phases runs 29.53 days.
A full cycle is about 29.5 days, so a quarter cycle will be 1/4 of this, on average (divide 29.5 by 4). This is just an average; since the Moon's orbit is not a perfect circle, it may vary a bit.
Whatever moon phase you're looking at, it was the same 29.53 days ago, and it'll be the same again after another 29.53 days.
7 days
7 days
29.5 days
1 month.
29.53 days
29.5 days
29.5 days from new moon to new moon.
The full lunar cycle is roughly 4 weeks, and from full-moon to new-moon is half the cycle, so it would take (roughly) 2 weeks to go from full to new moon.
29.53 days after the last one.
It takes about 29.5 days for the moon to complete one full phase cycle, from new moon to full moon and back to new moon again.
14-365 days holla
It takes about 29.5 days for the moon to go from one new moon phase to the next new moon phase.