(According to tradition, Brahm Muhoort is 3 Naadee - appx 1.5 hours,  before Sun rise. When the devotee rises in this way, they are joined by other devotees, in stillness and silence. In this way, the atmosphere about you becomes sacred, congenial and supportive. The grace of early morning is Brahm Muhoort, meaning, "Time of God". This is a favorable time for Saadhanaa, when most the world is in deep sleep. According to Aayur Ved, the early morning is Sattwa, during the day is Rajas, and Tamas prevails at night. It is traditional to rise early, before the Sun rises, to bathe and begin your morning meditation, all in the sacred atmosphere of Brahm Muhoort. Before the Sun rises the earth is still, the vibrations of many minds in turmoil have yet to be stirred, so that a pure mental ray pervades your surroundings.

How Long is Brahm Muhoort?
Brahm Muhoort is good for spiritual pursuits and it is more important in Yaugik, Taantrik and Vaidik learning and its spiritual practices, it is last Yaam of the night, so it may start from almost 3 to 4.30 am - one Yaam is approximately of 3 hrs duration). Some says it is the last part of Yaamaardh (1/2 Yaam means 1.30 hours before sunrise). A day is made up of 24 hours or 8 Yaam. It means that 1 Yaam is of 3 hours.

1 Day  =  8 Yaam (Pahar or Prahar) - 3 hours  or 
1 Day  =  30 Muhoort  = 48 minutes x 30 = 1440 minutes = 60 minutes x 24 = 1440 minutes

1 Ghadee  =  24 minutes
2 Ghadee  =  48 minutes
1 Muhoort  =  48 minutes = 2 Ghadee
1 Yaam  =  3 hours (there are 8 Yaam in a day, so 24 hours / 8 = 3 hours

A Muhoort consists of 2 Ghatee. Thus,  span for the Brahm Muhoort is of 1 and 1/2 hours (or more specifically 1 hour and 36 minutes). Brahm Muhoort is that time which is just 1 and 1/2 hour before local sunrise time. Find out the local sunrise time on the selected day and minus 1 and 1/2 hrs from that to begin the Brahm Muhoort of that day.

It is stated in Manu Sanhitaa that 18 Nimesh (twinkling of the eye) are 1 Kshan, 30 Kshan are 1 Kalaa, 30 Kalaa are one Muhoort, and as many (Muhoort) one day and night - 30 Muhoort

Muhoort (48 minutes) the word attached to "Brahm" should not be confused on other Muhoort we take for selection for auspicious pursuits. In teaching students for the first time, many astrological Guru select this Muhoort but not in other cases, not even in Vidyaa Aarambh Muhoort.

Though in past, Vaidik Muhoort was the last 29th Muhoort time was called Brahm Muhoort (15 Muhoort on day and 15 Muhoort in night) so the 29th Muhoort is called Brahm Muhoort, so it starts 96 minutes before sunrise - almost 1 and 1/2 hour time), if someone takes it this way it comes around 4.30 to 6 am (assuming that sunrise is at 6 am and it is safe to take this way if the person is living near equator, but if somebody is living in far Northern places, one must check the sunrise and sunset time.