What is Kalpa, Manvantara, and Yuga in Vedic Dharma ? 
The Universe which we live in starts with the origin of Brahma Dev. It runs till Brahma’s life and after His death another cycle starts with the creation of next Brahma by Sri Vishnu.Brahma’s lifespan extends to 100 years.His 1 day consists of a day and a night.During day Universe runs and during night everything dissolves and nothing left and Sri Vishnu goes to sleep on Sheshnag.Universe again starts on the second day at daytime and this cycle goes on till Brahma’s lifespan.A daytime of Brahma consists of a duration of 1 Kalpa and night time is also of same duration.1 Kalpa equals 14 Manvantaras.1 Manvantara consists of 71 Mahayugas.1 Mahayuga consists of 4 Yugas called Chaturyuga and they are in the ratio of 4:3:2:1.Kaliyuga age is 1200 divine years or 432000 human years.1 divine year is equal to 360 human years.Satyuga is 4 times Kaliyuga ie 4800 divine years or 1728000 human years.Tretayuga is 3 times Kaliyuga ie 3600 divine years or 1296000 human years.Dwaparyuga is 2 times Kaliyuga ie 2400 divine years or 864000 human years.1 Mahayuga is 12000 divine years or 4,320,000 human years.1 Manvantara is 852,000 divine years or 306,720,000 human years.Before first Manvantara and after last Manvantara and between each Manvantara there exists Sandhikalas, a transitional period equals to 1 Satyuga ie 4800 divine years in which Earth is submerged in Garbodhaka ocean for cleansing purpose.So there are 15 Sandhikalas and 14 Manvantaras adding upto 12,000,000 divine years ie the age of 1 Kalpa.1 day of Brahma equals to 2 Kalpas ie 24,000,000 divine years.So Brahma’s 100 years lifespan is equal to 864,000,000,000 divine years or 311.04 trillion human years.Brahma is in his 51st year and first day.So currently the ongoing Kalpa name is Sweta Kalpa, ongoing Manvantara is the seventh one called Vaivasvata Manvantara and the current Mahayuga is the 28th one out of 71 in which we are in Kaliyuga which has been started in 3102 BC and 5121 human years has been elapsed in this Kaliyuga.
