Time - As defined by Vedas

 The world exists in one form for a fixed period and then for that very period, it exists only in its material cause. The former is called "Brahma Din" and the latter " Brahma Ratri".

As the Atharva Veda sats, the Brahma Din is equal to  4320,000,000 years.

The Brahma Din is made up of 1000 Chaturyugins (4 Yugs) or Dibyayugs. 

Manu says - A Chaturyugins or Dibyayugs means a period of four yus - Satyug, Treta, Dwapar and Kaliyug and consists of 12,000 Dibya years - Satyug consits of 4800, Treta of 3600, Dwapar of 2400 and Kaliyug of 1200 Dibya years.

Now a Dibya year is equal to 360 ordinary years.

Thus,

Satyug = 4800 x 360 = 1,728,000 years

Treta = 3600 x 360 = 1,296,000 years

Dwapur = 2400 x 360 = 864,000 years

Kaliyug = 1200 x 360 =  432,000 years

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A Chaturyugi =. 4,320,000 years

Brahma Din =1000 Chaturyugi = 4,320,000,000 years.

This is the period for which the world will remain in its present form.

According to the Sankalp (from Surya Siddhanta), 6 Manwantras have passed and 7th Manwantras is passing and remaining 7 have still to come.

1 Brahma Din = 14 Manwantras

1 Manwantra = 71 Chaturyugins = 4,320,000 x 71 = 306,720,000 

As of this year (2021) :

Total 14 Manwantras

• 6 Manwantras have passed  = 306,720,000 * 6 = 1,840,320,000
• 7th Manwantra is active = 306,720,000
• 7 Manwantras are remaining = 306,720,000 * 7 = 2,147,040,000

Present Kaliyug is 28th Chaturyugi. Of this Chaturyugi (28th), 5,006 years of Kaliyug (the present sambat being 1963 Vicrama)* have passed.

Years passed in present Kaliyug = 5006 years have passed and remaining years in Kaliyug = 4,320,000 - 5006 = 426,004 years remaining

Thus of 7th Manwantra

• Total 71 Chaturyugins = 306,720,000 
• 27 Chaturyugi (already passed) = 4,320,000 * 27 = 116,640,000 years
• 28th Chaturyugi ( passed ) = Satyug + Treta +. Dwapar + 5006 years of Kaliyug
• 1,728,000 + 1,296,000 + 864,000 + 5006 = 3,893,006 years have passed
• Total number of years passed in 7th Manwantra = 116,640,000 + 3,893,006  = 120,533,006 years have passed
• 28th Chaturyugi ( still remaining ) = 4,320,000 -  3,893,006 =  426,994 years
• 43 Chaturyugi ( still remaining ) = 4,320,000 * 43 = 1,85,760,000 years
• Total remaining years in 7th Manwantra = 426,994 + 1,85,760,000   = 186,186,994 years

Total remaining days before the day of Final Dissolution = Remaining days of 7th Manwantras  + 7 pending Manwantras  = 186,186,994 + 2,147,040,000  =  2,333,226,994 years remaining

Taking current Smavat as 2077, so remaining years  =  2,333,226,994 - (2077 -1963) = 2,333,226,880 years remaining = 233 Crore years pending.