Hindu time measurement:
• a Lipta (लिप्ता) is approximately 0.4 seconds
• a Vighati (विघटि) is 60 Liptas, or approximately 24 seconds
• a Ghadika (घटि) is 60 Vighatis, or approximately 24 minutes
• a Muhurta is equal to 2 Ghadikas, or approximately 48 minutes
• a Nakshatra ahoratram (नक्षत्र अहोरत्रम्) or sidereal day is exactly equal to 30 Muhurtas (Note: A day is considered to begin and end at sunrise, not midnight.)
An alternate system described in the Vishnu Purana Time measurement section of the Vishnu Purana Book I Chapter III is as follows:
100 Truti = 1 Tatpara
30 Tatpara = 1 Nimesha
15 Nimeshas = 1 Káshthá
30 Káshthás = 1 Kalá
30 Kalás = 1 Kṣaṇa
12 Kṣaṇa = 1 Muhúrtta
30 Muhúrttas = 1 day (24 hours)
30 days = 1 month
6 months = 1 Ayana
2 Ayanas = 1 year or one day (day + night) of the gods
Small units of time used in the Vedas
• a Trasarenu is the combination of 6 celestial atoms.
• a Truti is the time needed to integrate 3 Trasarenus, or 1/1687.5th of a second.
• a Vedha is 100 Trutis.
• a Lava is 3 Vedhas.
• a Nimesha is 3 Lavas, or a blink.
• a Kshanas is 3 Nimeshas.
• a Kashthas is 5 Kshanas, or about 8 seconds.
• a Laghu is 15 Kashthas, or about 2 minutes.
15 Laghus make one Nadika, which is also called a danda. This equals the time before water overflows in a six-pala-weight [fourteen ounce] pot of copper, in which a hole is bored with a gold probe weighing four masha and measuring four fingers long. The pot is then placed on water for calculation.
2 Dandas make one Muhurta.
6 or 7 Dandas make one Yamah, or 1/4th of a day or night.
4 Praharas or 4 Yamas are in each day or each night.
LUNAR METRICS
a tithi (also spelled thithi ) or lunar day is defined as the time it takes for the longitudinal angle between the moon and the sun to increase by 12°. Tithis begin at varying times of day and vary in duration from approximately 19 to approximately 26 hours.
a paksa (also paksha) or lunar fortnight consists of 15 tithis
a masa or lunar month (approximately 29.5 days) is divided into 2 pakshas: the one between new moon and full moon is called gaura (bright) or shukla paksha; the one between full moon and new moon krishna paksha
a ritu is 2 masa
an ayanam is 3 rituhs
a year is 2 Aayanas
TROPICAL METRICS
a Yaama (याम) = 1/4th of a day(light) or night [ = 7½ Ghatis (घटि) = 3¾ Muhurtas (मुहूर्त) = 3 Horas (होरा) ]
4 Yaamas 1 half of the day (either day or night)
8 Yaamas 1 day (day + night)
an Ahoratram is a tropical day (Note: A day is considered to begin and end at sunrise, not midnight.)
Reckoning of time among other entities
Reckoning of time amongst the pitrs.
1 human day = 1/30 day of the pitrs
30 days of human is 1 month of human = 1 day of the pitrs
12 months of human = 1 year of the pitrs
The lifespan of the pitrs is 100 years of the pitrs (= 3,600 human years)
Reckoning of time amongst the Devas.
1 human year = 1 day of the Devas.
30 days of the Devas = 1 month of the Devas.
12 months of the Devas = 1 year of the Devas
The lifespan of the Devas is 100 years of the Devas (= 36,000 human years)
The Vishnu Purana Time measurement section of the Vishnu Purana Book I Chapter III explains the above as follows:
2 Ayanas (six month periods, see above) = 1 year or one day (day + night) of the devas
360 days of the devas = 1 year of the devas
12,000 years of the devas = 4 Yugas
Reckoning of time for Brahma.
12,000 years of the Devas = 1 day of Brahma (4320,000,000 human years). This day is divided into 10, 000 parts called charanas.
The charanas are divided as follows:
The Four Yugas
4 charanas (1,728,000 solar years)Satya Yuga
3 charanas(1,296,000 solar years)Treta Yuga
2 charanas(864,000 solar years)Dwapara Yuga
1 charanas(432,000 solar years)Kali Yuga
The cycle repeats itself so altogether there are 1000 cycles of yugas in one day of Brahma.
One cycle of the above four yugas is one mahayuga (4.32 billion solar years)
A manvantara consists of 71 mahayugas (306,720,000 solar years). Each Manvantara is ruled by a Manu.
After each manvantara follows one Sandhi Kala of the same duration as a Krita Yuga (1,728,000 = 4 Charana). (It is said that during a Sandhi Kala, the entire earth is submerged in water.)
A kalpa consists of a period of 1,728,000 solar years called Adi Sandhi, followed by 14 manvantaras and Sandhi Kalas.
A day of Brahma equals
(14 times 71 mahayugas) + (15 x 4 Charanas)
= 994 mahayugas + (60 Charanas)
= 994 mahayugas + (6 x 10) Charanas
= 994 mahayugas + 6 mahayugas
= 1000 mahayugas
as is confirmed by the Gita statement
"sahasra-yuga paryantam ahar-yad brahmano viduH",
meaning, a day of brahma is of 1000 (maha-)yugas. Thus a day of Brahma, kalpa, is of duration: 4.32 billion solar years. Two kalpas constitute a day and night of Brahma
30 days of Brahma = 1 month of Brahma (259,200,000,000 human years)
12 months of Brahma = 1 year of Brahma (3,110,400,000,000 human years)
25 years of Brahma = 1 kalpa (77,760,000,000,000 human years)
2 kalpas = 1 parardha (155,520,000,000,000 human years)
2 parardhas = 100 years of Brahma, the lifespan of Brahma (311,040,000,000,000 human years)
The Vishnu Purana Time measurement section of the Vishnu Purana Book I Chapter III explains the above as follows:
360 days of the gods = 1 year of the gods
12,000 years of the gods = 4 Yugas
1,000 sets of 4 Yugas = a day of Brahmá
50 years of Brahma = 1 Pararddham
100 years of Brahma = 1 Param
4,000 + 400 + 400 = 4,800 years = 1 Krita Yuga
3,000 + 300 + 300 = 3,600 years = 1 Tretá Yuga
2,000 + 200 + 200 = 2,400 years = 1 Dwápara Yuga
1,000 + 100 + 100 = 1,200 years = 1 Kali Yuga
Alternately, the reigns of 7 Rishis, Indra and Manu = 1 Manwantara = 71x12,000+A (A is not given) = 852,000 years of the gods+A (A is not given)
14 Manwantaras = a day of Brahmá
VEDIC TIME UNITS GREATER THAN A KALPA
Ancient vedic cosmology takes into account handful of time spans which are even greater than one Kalpa or a day of Brahma. One such unit is a "Maha-Kalpa" which is composed of 36000 such days of Brahma. One Maha-Kalpa is considered as the lifetime of Brahma. There are time units which are larger than one Maha-Kalpa. The largest of them has been calculated as several quadrillions of human years. This precise and massive calculations indicate one important aspect of vedic time system, that, whenever the term "Infinity" has been mentioned in Vedas, it does not indicate something very large. Instead, it appears that the term is meant to refer its literal synonym itself.
https://www.youtube.com/watch?v=1Pz9L7PDmg4https://www.youtube.com/watch?v=1Pz9L7PDmg4