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 (Vedic)-origin known as ayanamsas (Sanskrit: 'ayana' "movement" + 'aṃśa''' "component"), 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 (also known as Vedic 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 ≈ 29.6 μs reṇu () 60 truti ≈ 18.5 μs lava () 60 renu ≈ 1,111 μs () 60 lava ≈ 66.66 ms () 6 ≈ 0.4 s vipala () Length of breath in Sukhasana of healthy person () 10 ≈ 4 s pala () 60 or 6 ≈ 24 s () () () 60 ≈ 1.44 ks (24 min) () daṇḍa () () 2 ≈ 2.88 ks (48 min) (sidereal day; ) 60 ≈ 86.4 ks (24 h) 30
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 (24 min) () 2 ghatika ≈ 2.88 ks (48 min) (sidereal day) 30 ≈ 86.4 ks (24 h)
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 (lunar day), pakṣa (lunar fortnight), māsa (lunar month), ṛitu (season), ayanam (half-year), and varsha (lunar year) 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 (lunar day) Time for 12° increase of longitudinal angle between Moon and Sun ≈ 1 day (varies 19–26 hours) (lunar fortnight) 15 tithis ≈ 15 days (lunar month) 2 : gaura (bright) or during waxing moon; (dark) during waning moon ≈ 30 days (29.5 days) (season) 2 ≈ 60 days ayanam 3 ≈ 180 days varsha (lunar year) 2 ayanams ≈ 360 days (354.36707 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 (base unit), yāma (a period of 7.5 ghaṭis), and ahorātram (a full day comprising 8 yāmas). 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 (tropical day starting at sunrise)
Cosmic metrics The table below contains calculations of cosmic Hindu units of time as experienced by different entities, namely humans, Pitris (forefathers), Devas (gods), Manu (progenitor of humanity), and Brahma (creator god). Calculations use a traditional 360-day year (twelve 30-day months) and a standard 24-hour day for all entities.
+ Cosmic units of time Unit Definition Human Pitri Deva Manu Brahma 36,000 kalpa & pralaya 311,040,000,000,000 yr 10,368,000,000,000 yr 864,000,000,000 yr ~ 100 yr length 155,520,000,000,000 yr 5,184,000,000,000 yr 432,000,000,000 yr ~ 50 yr kalpa 14 m + 15 ms; 1,000 cy 4,320,000,000 yr 144,000,000 yr 12,000,000 yr ~ 12 h pralaya kalpa length manvantara [m] 71 306,720,000 yr 10,224,000 yr 852,000 yr 100 yr [ms] length 1,728,000 yr 57,600 yr 4,800 yr ~ 17.28 s [cy] , , & Kali-yugas 4,320,000 yr 144,000 yr 12,000 yr ~ 43.20 s sum total 1,728,000 yr 57,600 yr 4,800 yr ~ 17.28 s length 144,000 yr 4,800 yr 400 yr ~ 1.44 s 4 Kali-yuga lengths 1,440,000 yr 48,000 yr 4,000 yr ~ 14.40 s sum total 1,296,000 yr 43,200 yr 3,600 yr ~ 12.96 s length 108,000 yr 3,600 yr 300 yr ~ 1.08 s 3 Kali-yuga lengths 1,080,000 yr 36,000 yr 3,000 yr ~ 10.80 s sum total 864,000 yr 28,800 yr 2,400 yr ~ 8.64 s length 72,000 yr 2,400 yr 200 yr ~ 0.72 s 2 Kali-yuga lengths 720,000 yr 24,000 yr 2,000 yr ~ 7.20 s Kali-yuga sum total 432,000 yr 14,400 yr 1,200 yr ~ 4.32 s Kali-yuga length 36,000 yr 1,200 yr 100 yr ~ 0.36 s Kali-yuga 1,000 Deva years 360,000 yr 12,000 yr 1,000 yr ~ 3.60 s
Lifespans Hindu texts define lifespans differently for humans, Pitris (forefathers), Devas (gods), Manus (progenitors of mankind), and Brahma (creator god). 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 (48-week year). A traditional human year is measured by the sun's northern (uttarayana) and southern (dakshinayana) 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 (~365.24-day 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 (Ujjain meridian) 17/18 February 3102BCE (proleptic Julian), corresponding to 22/23 January (proleptic Gregorian). We are currently halfway through Brahma's life (maha-kalpa), 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 (2nd half or parardha) 1st month of 12 1st kalpa (Shveta-Varaha Kalpa) of 30 7th manvantara (Vaivasvatha Manu) of 14 28th chatur-yuga of 71 4th yuga (Kali-yuga) of 4
A maha-kalpa is followed by a maha-pralaya (full dissolution) of equal length. Each kalpa (day of Brahma) is followed by a pralaya (night of Brahma or partial dissolution) of equal length. Preceding the first and following each manvantara is a manvantara-sandhya (connection period), each with a length of Krita-yuga ( Satya-yuga).
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 (Ursa major) residing in the "Magha" constellation. The current Kali-yuga will end with the Sun, Moon and Jupiter residing in the "Pushya" sector.Bharatbarsha – A Living Legend.
Human
The history of humanity is divided up into four yugas ( dharmic ages or world ages)— (pronounced Krita-yuga; Satya-yuga), , and Kali-yuga—each with a decline in dharmic practices and length, giving proportions (; pronounced charanas) of 4:3:2:1 (e.g. Satya: 100% start; Kali: 25% start, 0% end), 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 (pronounced chatur-yuga; mahā-yuga). Each yuga is divided into a main period ( yuga proper) and two yuga-sandhis ( ; connecting periods)— (dawn) and ( ; dusk)—where each yuga-sandhi lasts for 10% of the main period. Lengths are given in divine years ( celestial or Deva years), where a divine year lasts for 360 solar (human) years. A chatur-yuga lasts for 4.32 million solar (12,000 divine) 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 yugaKali-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: = (current year + Kali-yuga start year) − year zero = ( + 3102) − 1 = years ago
Kali-yuga-sandhya (dawn) ends in CE: = Kali-yuga-sandhya − elapsed Kali-yuga = 36,000 − = years from now
Kali-yuga-sandhyamsa (dusk) starts in CE: = (Kali-yuga − Kali-yuga-sandhyamsa) − elapsed Kali-yuga = (432,000 − 36,000) − = years from now
Kali-yuga ends in CE: = Kali-yuga − elapsed Kali-yuga = 432,000 − = years from now
+ Current Kali Yuga Part Start (– End) Length Kali-yuga-sandhya (dawn)* 3102BCE 36,000 (100) Kali-yuga (proper) 32,899CE 360,000 (1,000) Kali-yuga-sandhyamsa (dusk) 392,899–428,899CE 36,000 (100) Years: 432,000 solar (1,200 divine)
Current chatur yuga
A chatur-yuga lasts for 4.32million years, where the current is the 28th of 71:
Started in BCE: = (chatur-yuga − Kali-yuga) + elapsed Kali-yuga = (4,320,000 − 432,000) + = years ago ≈ million years ago
Ends in CE: = Kali-yuga − elapsed Kali-yuga = 432,000 − = years from now
+ 28th chatur-yuga Yuga Start (– End) Length Krita (Satya) 3,891,102BCE 1,728,000 (4,800) Treta 2,163,102BCE 1,296,000 (3,600) Dvapara 867,102BCE 864,000 (2,400) Kali* 3102BCE428,899CE 432,000 (1,200) Years: 4,320,000 solar (12,000 divine)
Pitri The lifespan of the Pitris (forefathers) lasts for 100 of their years. 24 hours (1 day & night) of Pitris = 1 solar month (masa; Moon's two 15-day fortnights: bright and dark) 30 days (1 month) of Pitris = 30 solar months (2.5 solar years) 12 months (1 year) of Pitris = 30 solar years (1 month of Devas) 100 years (lifespan) of Pitris = 3,000 solar years
Deva The lifespan of the Devas (gods) lasts for 100 of their years. 24 hours (1 day & night) of Devas = 1 solar year (Sun's two 180-day motions: northern and southern) 30 days (1 month) of Devas = 30 solar years (1 year of Pitris) 12 months (1 year) of Devas = 360 solar years 100 years (lifespan) of Devas = 36,000 solar years
Manu
The lifespan of the Manus (progenitors of mankind) lasts for 100 of their years. Each Manu reigns over a period called a manvantara, each lasting for 71 chatur-yugas (306.72 million years). A total of 14 Manus reign successively in one kalpa (day of Brahma). Preceding the first and following each manvantara is a (connection period), each lasting the duration of Satya-yuga (1.728 million years). During each ( manvantara-sandhi), Earth (Bhu-loka) is submerged in water. 24 hours (1 day & night) of Manu = 8,520 solar years 30 days (1 month) of Manu = 255,600 solar years 12 months (1 year) of Manu = 3,067,200 solar years 100 years (lifespan) of Manu = 306,720,000 solar years (71 chatur-yugas)
Current manvantara A manvantara lasts for 306.72million years, where the current (ruled by Vaivasvatha Manu) is the 7th of 14: Started in the past: = elapsed 28th chatur-yuga + 27 chatur-yugas = (chatur-yuga − Kali-yuga) + elapsed Kali-yuga + 27 chatur-yugas = (4,320,000 − 432,000) + + (27 × 4,320,000) = years ago ≈ million years ago
Ends in the future: = remaining 28th chatur-yuga + 43 chatur-yugas = (Kali-yuga − elapsed Kali-yuga) + 43 chatur-yugas = (432,000 − ) + (43 × 4,320,000) = years from now ≈ million years from now
Brahma