A lunation is the time interval between two similar lunar phases (from New Moon to New Moon or from Full Moon to Full Moon). For this table I used from New Moon to New Moon, when the apparent geocentric ecliptical longitudes of the Moon and the Sun are equal. The mean duration of the lunation is 29d 12h 44m, but it is variable...
www.pierpaoloricci.it/dati/lunazioni_eng.htm