Vedic Time Units
| Prāṇa | Vinādī | Nādī | Ahorātra | Māsa | Saṃvatsara | Caturyuga | Manvantara | |
|---|---|---|---|---|---|---|---|---|
| Prāṇa | 1 | 6 | 360 | 21600 | 648000 | 7.78 × 106 | 3.36 × 1013 | 2.39 × 1015 |
| Vinādī | 0.166667 | 1 | 60 | 3600 | 108000 | 1.3 × 106 | 5.6 × 1012 | 3.98 × 1014 |
| Nādī | 0.00277778 | 0.0166667 | 1 | 60 | 1800 | 21600 | 9.33 × 1010 | 6.63 × 1012 |
| Ahorātra | 4.62963e-05 | 0.000277778 | 0.0166667 | 1 | 30 | 360 | 1.56 × 109 | 1.1 × 1011 |
| Māsa | 1.54321e-06 | 9.25926e-06 | 0.000555556 | 0.0333333 | 1 | 12 | 5.18 × 107 | 3.68 × 109 |
| Saṃvatsara | 1.29 × 10-7 | 7.72 × 10-7 | 4.62963e-05 | 0.00277778 | 0.0833333 | 1 | 4.32 × 106 | 3.07 × 108 |
| Caturyuga | 2.98 × 10-14 | 1.79 × 10-13 | 1.07 × 10-11 | 6.43 × 10-10 | 1.93 × 10-8 | 2.31 × 10-7 | 1 | 71 |
| Manvantara | 4.19 × 10-16 | 2.52 × 10-15 | 1.51 × 10-13 | 9.06 × 10-12 | 2.72 × 10-10 | 3.26 × 10-9 | 0.0140845 | 1 |
Prāṇa
The word Prāṇa is Sanskrit for breath — the same word used in yoga and Vedic philosophy to mean vital life force. There are 21,600 Prāṇas in one Ahorātra (sidereal day). If we divide 21,600 by 24 hours, then divide again by 60 minutes, we get 15 — the number of breaths per minute. Modern medical literature widely cites the normal adult respiratory rate as 12–20 breaths per minute, with 15 as the midpoint. Those living by Vedic principles sought to live in harmony with nature, and using the breath as a unit of time is another expression of that principle in practice.
To find the length of a Prāṇa in seconds, we start with the number of seconds in a civil day.
24 hours × 60 minutes × 60 seconds = 86,400 seconds ÷ 21,600 = 4 seconds per Prāṇa
Vinādī & Nādī
One Vinādī is six Prāṇas. Sixty Vinādīs make one Nādī, which is 1/60 of a sidereal day (SS 1.11).
4 seconds/Prāṇa × 6 Prāṇas = 24 seconds per Vinādī
24 seconds/Vinādī × 60 Vinādīs = 1,440 seconds per Nādī (24 minutes)
Ahorātra
The word Ahorātra is composed of two Sanskrit words — Aho, meaning day, and Rātra, meaning night. Sixty Nādīs constitute one Ahorātra, one full day (SS 1.12).
60 Nādīs × 1,440 seconds/Nādī = 86,400 seconds = 1,440 minutes = 24 hours exactly.
Civil Day
The civil day — called the Sāvana day in the Surya Siddhanta — is what we commonly refer to as a day, measured from sunrise to sunrise (SS 1.12). Each civil day corresponds to approximately 0.9856° of solar movement — slightly less than the full 1° of a solar day.
360° ÷ 365.2588 civil days per year = 0.9856° per civil day
The derivation of 365.2588 is covered in the Saṃvatsara section. The count of civil days elapsed since a fixed reference point — called an epoch — is known as the Ahargana, the fundamental unit through which planetary positions are calculated in the Surya Siddhanta, covered in a dedicated section.
Lunar Day
A lunar day is known as a tithi. One tithi is defined as each successive 12° of separation between the Sun and Moon, accumulating up to 360° for the 30th tithi, giving 30 tithis per lunar month. Tithis are covered in detail in the Māsa section.
Māsa
A Māsa (month) consists of thirty days. Days may be defined as civil days, solar days, or tithis (lunar days).
Solar Month
A solar month is the period of the Sun's transit through one zodiac sign (SS 1.13). There are twelve zodiac signs spanning the full 360° ecliptic — dividing by 12 gives 30° per sign, so each solar month is exactly 30° of solar movement. Unlike the lunar month, the solar month has no individual names — it exists purely as a measure of the Sun's progress through the ecliptic.
Lunar Month
A new lunar month begins at the new moon (Amāvasyā). A tithi is determined by dividing the full 360° of the Moon's path through the ecliptic by 30, giving 12° per tithi. The Moon begins each tithi 12° further ahead of the Sun than the last. Tithi 1 begins at 0° separation and tithi 30 ends at 360°. Tithis are counted in two fortnights of fifteen: śukla pakṣa (waxing fortnight), beginning at the new moon and ending at the full moon (Pūrṇimā), and kṛṣṇa pakṣa (waning fortnight), beginning at the full moon and ending at the new moon.
A lunar month is approximately 29.5306 civil days in length. This is derived from the values given in the Surya Siddhanta:
12 months × 4,320,000 solar years + 1,593,336 Adhikamāsas (SS 1.38) = 53,433,336 lunar months per Caturyuga
1,577,917,828 civil days (SS 1.37) ÷ 53,433,336 lunar months = 29.5306 civil days per lunar month
Note: Adhikamāsa is an intercalary month periodically inserted to synchronize the lunar and solar calendars. It is covered in detail in the Saṃvatsara section.
| # | Name | Śukla Pakṣa | Kṛṣṇa Pakṣa |
|---|---|---|---|
| 1 | Pratipadā | 12° | 192° |
| 2 | Dvitīyā | 24° | 204° |
| 3 | Tṛtīyā | 36° | 216° |
| 4 | Caturthī | 48° | 228° |
| 5 | Pañcamī | 60° | 240° |
| 6 | Ṣaṣṭhī | 72° | 252° |
| 7 | Saptamī | 84° | 264° |
| 8 | Aṣṭamī | 96° | 276° |
| 9 | Navamī | 108° | 288° |
| 10 | Daśamī | 120° | 300° |
| 11 | Ekādaśī | 132° | 312° |
| 12 | Dvādaśī | 144° | 324° |
| 13 | Trayodaśī | 156° | 336° |
| 14 | Caturdaśī | 168° | 348° |
| 15 | Pūrṇimā (Śukla Pakṣa) Amāvasyā (Kṛṣṇa Pakṣa) | 180° | 360° |
Saṃvatsara
Saṃvatsara is one solar year — 12 Māsas, or the Sun completing one full revolution through all 12 rāśis.
Solar Year
One solar year is measured by one revolution of the Sun through the ecliptic. There are twelve rāśis that the Sun traverses in one year. Their degree ranges are listed below.
| # | Rāśi | Western Name | Degrees |
|---|---|---|---|
| 1 | Meṣa | Aries | 0°–30° |
| 2 | Vṛṣabha | Taurus | 30°–60° |
| 3 | Mithuna | Gemini | 60°–90° |
| 4 | Karka | Cancer | 90°–120° |
| 5 | Siṃha | Leo | 120°–150° |
| 6 | Kanyā | Virgo | 150°–180° |
| 7 | Tulā | Libra | 180°–210° |
| 8 | Vṛścika | Scorpio | 210°–240° |
| 9 | Dhanu | Sagittarius | 240°–270° |
| 10 | Makara | Capricorn | 270°–300° |
| 11 | Kumbha | Aquarius | 300°–330° |
| 12 | Mīna | Pisces | 330°–360° |
Civil Days per Solar Year
The following calculation derives the number of civil days per solar year from values given in the Surya Siddhanta.
Star revolutions (SS 1.34) − Sun revolutions (SS 1.29) = Sun risings per Caturyuga (civil days)
1,582,237,828 − 4,320,000 = 1,577,917,828 (SS 1.37)
÷ 4,320,000 solar years (SS 1.15) = 365.258757 civil days per solar year
The twelve months of the Vedic calendar are listed below.
| Presiding Name of Viṣṇu | Vedic Month | Approximate Gregorian Range |
|---|---|---|
| Mādhava | Caitra | March 22 – April 20 |
| Madhusūdana | Vaiśākha | April 21 – May 21 |
| Trivikrama | Jyeṣṭha | May 22 – June 21 |
| Vāmana | Āṣāḍha | June 22 – July 21 |
| Śrīdhara | Śrāvaṇa | July 23 – August 22 |
| Hṛṣīkeśa | Bhādrapada | August 23 – September 21 |
| Padmanābha | Āśvina | September 22 – October 21 |
| Dāmodara | Kārtika | October 22 – November 19 |
| Keśava | Mārgaśīrṣa | November 20 – December 18 |
| Nārāyaṇa | Pauṣa | December 19 – January 16 |
| Govinda | Māgha | January 17 – February 14 |
| Viṣṇu | Phālguna | February 15 – March 20 |
The association of each Vedic month with a name of Viṣṇu is a Gauḍīya Vaiṣṇava tradition.
Adhikamāsa
Adhikamāsa is an extra month that appears roughly every three years, due to the accumulating difference between the solar and lunar years. The lunar year falls short of the solar year by 0.3687 months each year. The calculation uses two values from the Surya Siddhanta:
- Adhikamāsa per Caturyuga: 1,593,336 (SS 1.38)
- Solar years per Caturyuga: 4,320,000 (SS 1.15)
1,593,336 ÷ 4,320,000 = 0.3687 Adhikamāsas per year
As the Vedic calendar is based on the lunar year, an additional month is periodically inserted to synchronize the two.
1 ÷ 0.3687 = 2.7158 years, or roughly every 32.5 months.
Caturyuga
The word Caturyuga means four (catur) ages (yuga) — Kṛta (also known as Satya Yuga), Tretā, Dvāpara, and Kali — one complete cycle of cosmic time as described in the Surya Siddhanta. All astronomical constants in the SS are given per Caturyuga — this is why 4,320,000 has appeared throughout our calculations, and why it serves as the natural unit of the Vedic astronomical framework.
According to the Surya Siddhanta (SS 1.17), the length of each age is calculated by taking one tenth of the total Caturyuga and multiplying by 4, 3, 2, and 1 respectively. Each age also has a transitional period at its beginning and end, called Sandhyā and Sandhyāṃśa respectively, each 1/6th the length of its age (SS 1.17).
4,320,000 ÷ 10 = 432,000 years (base unit)
| Age | Multiplier | Length (years) | Transition (years) |
|---|---|---|---|
| Kṛta Yuga | 4 | 1,728,000 | 288,000 |
| Tretā Yuga | 3 | 1,296,000 | 216,000 |
| Dvāpara Yuga | 2 | 864,000 | 144,000 |
| Kali Yuga | 1 | 432,000 | 72,000 |
| Total | 10 | 4,320,000 |
It should be noted that the four Yuga cycles do not affect the entire middle planetary realm. Śrīla Viśvanātha Cakravartī Ṭhākura, in his purport to Śrīmad Bhāgavatam 5.19.19, quotes the Viṣṇu Purāṇa on this point:
catvāri bhārate varṣe yugānyatra mahāmune
kṛtaṃ tretādvāparaśca kaliścānyatra na kvacit
"O great sage! In Bhārata-varṣa there are Satya, Tretā, Dvāpara and Kali Yugas, which do not exist elsewhere."
Note: Our Earth planet is situated within Bhārata-varṣa.
Manvantara
In Vedic theology a Manvantara is ruled by a celestial being with the title Manu. He is said to rule over the middle realm we call Bhu-Maṇḍala, of which our Earth globe is a part. It consists of 71 Caturyuga cycles. After the last yuga cycle completes, a deluge the length of one Kṛta Yuga floods this middle realm.
71 × 4,320,000 = 306,720,000 years per Manvantara
Kalpa
A Kalpa is not a unit of time but a period consisting of 14 Manvantaras, each accompanied by a deluge (Pralaya) upon completion. There is also a deluge at the beginning of a Kalpa before the first Manvantara begins, making it a total of 15 deluges. Each deluge is the size of one Kṛta Yuga.
Both the Manvantaras and the deluges can be expressed in Caturyugas to find the total.
14 Manvantaras × 71 Caturyugas = 994 Caturyugas
15 deluges × 1,728,000 years (Kṛta Yuga) ÷ 4,320,000 = 6 Caturyugas
994 + 6 = 1,000 Caturyugas per Kalpa
Kalpa as a Unit
A Kalpa can be expressed as a unit of time with one restriction: it cannot be converted to Manvantaras. As a Kalpa is composed of both Manvantaras and deluges, a direct conversion to Manvantaras is not possible. Taking one Kalpa to be 1,000 Caturyugas, conversion between the two is straightforward.
Divine Time
In Vedic cosmology, creation is split into three realms: the upper realm, middle realm, and lower realm. The time scale of these realms functions at a different rate than our own.
| Unit | Equivalent |
|---|---|
| 1 Divine day | 1 solar year (SS 1.13) |
| 1 Divine year | 360 divine days = 360 solar years (SS 1.14) |
| 1 Caturyuga | 12,000 divine years = 4,320,000 solar years (SS 1.15) |
Lord Brahma's Time Scale
Lord Brahma's time scale is even higher than that of the upper realms. One Kalpa is the length of one day in Brahma's life. His night is equal in length.
1 Brahma day = 1 Kalpa
1 Brahma night = 1 Kalpa
1 Brahma Ahorātra = 2 Kalpas
In divine years:
2 Kalpas × 12,000,000 divine years = 24,000,000 divine years per Ahorātra
24,000,000 × 360 = 8,640,000,000 divine years per Brahma year
8,640,000,000 × 100 = 864,000,000,000 divine years — Brahma's lifespan
In Caturyugas and solar years:
2 Kalpas × 1,000 Caturyugas = 2,000 Caturyugas per Ahorātra
2,000 × 360 = 720,000 Caturyugas per Brahma year
720,000 × 100 = 72,000,000 Caturyugas — Brahma's lifespan
72,000,000 × 4,320,000 = 311,040,000,000,000 solar years
Based on this scale, the higher one goes the faster time moves for the lower realms. One day of Brahma consists of millions of years.