Hindu units of time
Hindu units of time are described in Hindu texts ranging from microseconds to trillions of years, including cycles of cosmic time that repeat general events in Hindu cosmology. Time is described as eternal. Various fragments of time are described in the Vedas, Manusmriti, Bhagavata Purana, Vishnu Purana, Mahabharata, Surya Siddhanta etc.
Sidereal metrics
Sidereal astrology maintains the alignment between signs and constellations via corrective systems of Hindu -origin known as ayanamsas, to allow for the observed precession of equinoxes, whereas tropical astrology ignores precession. This has caused the two systems, which were aligned around 2,000 years ago, to drift apart over the centuries.Ayanamsa systems used in Hindu astrology include the Lahiriayanamsa and the Raman ayanamsa. The Fagan-Bradley ayanamsa is an example of an ayanamsa system used in Western sidereal astrology. As of 2020, zodiacal signs calculated using the Sri Yukteswar ayanamsa were around 23 degrees behind tropical zodiacal signs. Per these calculations, persons born between March 12 - April 12, for instance, would have the sun sign of Pisces. By contrast, persons born between March 21 - April 19 would have the sun sign of Aries per tropical calculations.
Sidereal Units:
| Unit | Definition | Value in SI units |
| truti | base unit | ≈ 308.6 ns |
| reṇu | 60 truti | ≈ 18.5 μs |
| lava | 60 renu | ≈ 1,111 μs |
| 60 lava | ≈ 66.66 ms | |
| 6 | ≈ 0.4 s | |
| vipala | 6 | ≈ 0.4 s |
| 10 | ≈ 4 s | |
| pala | 60 or 6 | ≈ 24 s |
| 60 or 6 | ≈ 24 s | |
| 60 or 6 | ≈ 24 s | |
| 60 | ≈ 1.44 ks | |
| 60 | ≈ 1.44 ks | |
| daṇḍa | 60 | ≈ 1.44 ks |
| 2 | ≈ 2.88 ks | |
| 60 | ≈ 86.4 ks | |
| 30 | ≈ 86.4 ks |
According to :
| Unit | Definition | Value in SI units |
| truti | base unit | ≈ 29.6 μs |
| tatpara | 100 truti | ≈ 2.96 ms |
| nimesha | 30 tatpara | ≈ 88.9 ms |
| 18 nimesha | ≈ 1.6 s | |
| 30 | ≈ 48 s | |
| ghatika | 30 | ≈ 1.44 ks |
| 2 ghatika | ≈ 2.88 ks | |
| 30 | ≈ 86.4 ks |
Small units of time used in the Vedas:
| Unit | Definition | Value in SI units |
| base unit | ≈ 26.3 μs | |
| 2 | ≈ 52.67 μs | |
| 3 | ≈ 158 μs | |
| 3 | ≈ 474 μs | |
| vedha | 100 | ≈ 47.4 ms |
| lava | 3 vedha | ≈ 0.14 s |
| 3 lava | ≈ 0.43 s | |
| 3 | ≈ 1.28 s | |
| 5 | ≈ 6.4 s | |
| laghu | 15 | ≈ 96 s |
| danda | 15 laghu | ≈ 1.44 ks |
| 2 danda | ≈ 2.88 ks | |
| 30 | ≈ 86.4 ks | |
| masa | 30 | ≈ 2,592 ks |
| ritu | 2 masa | ≈ 5,184 ks |
| ayana | 3 ritu | ≈ 15,552 ks |
| samvatsara | 2 ayana | ≈ 31,104 ks |
| of Deva | 2 ayana | ≈ 31,104 ks |
Lunar metrics
The traditional lunar calendar system measures time based on the Moon's phases and its relation to the Sun. Unlike solar calendars, it uses units such as tithi, pakṣa, māsa, ṛitu, ayanam, and varsha to structure the year. This system was integral to ancient cultures for tracking time, planning festivals, and guiding agricultural practices. The following section provides an overview of these key time units and their relationships:| Unit | Definition | Equivalence |
| tithi | Time for 12° increase of longitudinal angle between Moon and Sun | ≈ 1 day |
| [paksha|] | 15 tithis | ≈ 15 days |
| 2 : gaura or during waxing moon; during waning moon | ≈ 30 days | |
| [Ritu (Hindu calendar)|] | 2 | ≈ 60 days |
| ayanam | 3 | ≈ 180 days |
| varsha | 2 ayanams | ≈ 360 days |
Tropical metrics
Tropical metrics are time units used to measure intervals based on the tropical year and related cycles. This system includes units such as ghaṭi, yāma, and ahorātram. The following section explains these units and their approximate durations, offering insight into how time is organized in relation to the tropical year:| Unit | Definition | Equivalence |
| base unit | ≈ 24 minutes | |
| 7.5 | ≈ 3 hours | |
| 8 | ≈ 24 hours |
Cosmic metrics
The table below contains calculations of cosmic Hindu units of time as experienced by different entities, namely humans, Pitris, Devas, Manu, and Brahma. Calculations use a traditional 360-day year and a standard 24-hour day for all entities.Lifespans
define lifespans differently for humans, Pitris, Devas, Manus, and Brahma. The division of a year for each is twelve 30-day months or 360 days, where a day is divided into a 12-hour day proper and 12-hour night. A 30-day month amounts to four 7-day weeks with an extra 8th day every two weeks. A traditional human year is measured by the sun's northern and southern movements in the sky, where the new year commences only when the sun returns to the same starting point and a pause on the commencement otherwise. Ebenezer Burgess postulates an intercalary month was inserted every five years to anciently maintain the correspondence of the 360-day years with the true solar years. For this reason, a traditional 360-day year is equivalent to a modern ~365.24-day solar or tropical year.| Unit | Human | Pitri | Deva | Manu | Brahma |
| Brahma year | 3,110,400,000,000 yr | 103,680,000,000 yr | 8,640,000,000 yr | ~ | 1 yr |
| Manu year | 3,067,200 yr | 102,240 yr | 8,520 yr | 1 yr | |
| Deva year | 360 yr | 12 yr | 1 yr | ~ | |
| Pitri year | 30 yr | 1 yr | ~ | ||
| Human year | 1 yr | ~ |
Cosmic date
According to Puranic sources, Krishna's departure marks the end of the human age of Dvapara-yuga and the start of Kali-yuga, which is dated to midnight on 17/18 February 3102BCE of the proleptic Julian calendar. We are currently halfway through Brahma's life, whose lifespan is equal to the duration of the manifested material elements, from which Brahma manifests his universe in kalpa cycles:- 51st year of 100
- 1st month of 12
- 1st kalpa of 30
- 7th manvantara of 14
- 28th chatur-yuga of 71
- 4th yuga of 4
Hindu texts specify that the start and end of each of the yugas are marked by astronomical alignments. This cycle's Treta-yuga began with 5 planets residing in the "Aries" constellation. This cycle's Dvapara-yuga ended with the "Saptarshi" constellation residing in the "Magha" constellation. The current Kali-yuga will end with the Sun, Moon and Jupiter residing in the "Pushya" sector.
Human
The history of humanity is divided up into four yugas —, [Treta Yuga|], [Dvapara Yuga|] and Kali-yuga—each with a 25% decline in dharmic practices and length, giving proportions of 4:3:2:1, indicating a de-evolution in spiritual consciousness and an evolution in material consciousness. Kali-yuga is followed by Satya-yuga of the next cycle, where a cycle is called a [Yuga Cycle|]. Each yuga is divided into a main period and two yuga-sandhis — and —where each yuga-sandhi lasts for 10% of the main period. Lengths are given in divine years, where a divine year lasts for 360 solar years. A chatur-yuga lasts for 4.32 million solar years with 1,728,000 years of Krita-yuga, 1,296,000 years of Treta-yuga, 864,000 years of Dvapara-yuga, and 432,000 years of Kali-yuga.Current ''yuga''
Kali-yuga lasts for 432,000 years and is the 4th of 4 yugas in a cycle as well as the current yuga, with two sandhyas, each lasting for 36,000 years:Kali-yuga started in 3102BCE:Kali-yuga-sandhya ends in CE:Kali-yuga-sandhyamsa starts in CE:Kali-yuga ends in CE:Current ''chatur yuga''
A chatur-yuga lasts for 4.32million years, where the current is the 28th of 71:- Started in BCE:
- Ends in CE:
Pitri
The lifespan of the Pitris lasts for 100 of their years.- 24 hours of Pitris = 1 solar month
- 30 days of Pitris = 30 solar months
- 12 months of Pitris = 30 solar years
- 100 years of Pitris = 3,000 solar years
Deva
The lifespan of the Devas lasts for 100 of their years.- 24 hours of Devas = 1 solar year
- 30 days of Devas = 30 solar years
- 12 months of Devas = 360 solar years
- 100 years of Devas = 36,000 solar years
Manu
The lifespan of the Manus lasts for 100 of their years. Each Manu reigns over a period called a manvantara, each lasting for 71 chatur-yugas. A total of 14 Manus reign successively in one kalpa. Preceding the first and following each manvantara is a ', each lasting the duration of Satya-yuga. During each ', Earth is submerged in water.- 24 hours of Manu = 8,520 solar years
- 30 days of Manu = 255,600 solar years
- 12 months of Manu = 3,067,200 solar years
- 100 years of Manu = 306,720,000 solar years
Current ''manvantara''
A manvantara lasts for 306.72million years, where the current is the 7th of 14:- Started in the past:
- Ends in the future:
Brahma
The lifespan of Brahma lasts for 100 of his years. His 12-hour day or kalpa is followed by a 12-hour night or pralaya of equal length, each lasting for 4.32 billion years. A kalpa lasts for 1,000 chatur-yugas and has 14 manvantaras and 15 manvantara-sandhyas occurring in it. At the start of Brahma's days, he is re-born and creates the planets and the first living entities. At the end of his days, he and his creations are unmanifest. His 100-year life is called a, which is followed by a of equal length, where the bases of the universe, prakriti, is manifest at the start and unmanifest at the end of a maha-kalpa. His 100-year life is divided into two 50-year periods, each called a. In 100 360-day years, there are a total of 36,000 full days: 36,000 kalpas and 36,000 pralayas.- 12 hours of Brahma = 4.32 billion solar years
- 24 hours of Brahma = 8.64 billion solar years
- 30 days of Brahma = 259.2 billion solar years
- 12 months of Brahma = 3.1104 trillion solar years
- 50 years of Brahma = 155.52 trillion solar years
- 100 years of Brahma = 311.04 trillion solar years
Current ''kalpa''
A kalpa lasts for 4.32billion years, where the current is the 1st of 30 in his 1st month of his 51st year:- Started in the past:
- Ends in the future:
Current ''maha kalpa''
A maha-kalpa lasts for 311.04trillion years:- Started in the past:
- Ends in the future:
Hindu texts
''Mahabharata''
The Mahabharata describes units of time from a wink of the eye up to the days and nights of Brahma.''Manusmriti''
The Manusmriti describes units of time from a twinkling of the eye up to the days and nights of Brahma.According to Patrick Olivelle, most scholars take the table of contents to be an addition, but for him the account of time and cosmology to the aforementioned are out of place redactions. He feels the narrative should have ended when the initial command to "listen" was repeated, then transition to "learn".
Georg Bühler, whose translation has remained the standard for over a century according to Olivelle, translated 1.71 as 12,000 years in a four-aged period, same as Sir William Jones's translation, both based on Kulluka Bhatta's commentary. Medhatithi translated it as 12,000 four-aged periods in an age of the gods. Kulluka and Olivelle reject Medhatithi's interpretation based on 1.79 mentioning 12,000 without a qualifier and must be assumed as years.