The Encarta encyclopedia tells us how long this takes: For the moon to go from one phase to the next similar phase, or one lunar month, requires 29 days, 12 hr, 44 min, and 2.8 sec [1] .
(the moon; to go; from one phase; to the next similar phase, or one lunar month)
the moon
to go
from one phase to the next similar phase, or one lunar month