How man days does it take for the moon to go through all its phases?

The moon revolves around its axis and orbits Earth in exactly the same time of about 27.32 days, relative to the Sun. This causes the moon to be constantly presenting the same face to the earth.

Just like any other sphere illuminated by any other flashlight, 50% of the moon's surface is always illuminated by the sun. But because the relative positions are always changing, we see different amounts of the lighted portion from earth. The complete cycle of 'phases' as seen from earth repeats with a mean (average) interval of 29.530589 days (29 days, 12 hours, 44 minutes, 02.9 seconds).