Kalpa is a Sanskrit term meaning eon or long period and is used mainly in Buddhist and Hindu cosmology.
In Buddhism there are four different types of kalpas: The most commonly used kalpa lasts about 16 million years. A short-lived kalpa lasts about 1000 common kalpas or 16 billion years.
A medium-sized kalpa lasts about 320 billion years, equivalent to about 20 short kalpas. A large kalpa lasts about 4 medium-sized kalpas, about 1.28 billion years.
Gautama Buddha did not talk about the exact duration of a kalpa in years, but he offered several analogies for calculating it:
Imagine a huge empty cube at the beginning of a kalpa, with an edge length of about 25.6 km; once every hundred years, we insert a mustard seed into the cube. When the bucket is filled, the kalpa will end.
Imagine a rock mountain measuring 26x26x26 km (width, length, height). We take a small piece of cloth and rub it with it once every 100 years. When the mountain disappears worn out, the kalpa will end.
On one occasion, several monks wanted to know how many kalpas had elapsed to date. Buddha gave them a surprising analogy:
If you count the total number of grains of sand in the depths of the Ganges River, from where it begins to where it flows into the sea, even that number will be less than the number of kalpas that have already elapsed.
In Hinduism, one kalpa is equivalent to 4.32 billion years; a single Brahma day, or one thousand mahayugas, measures the length of the world. (Today, science estimates the age of the universe at about 13.8 billion years.) Each kalpa is divided into 14 kalpa's, each of which is divided into 14 kalpa's, each of which is divided into 14 kalpa's, each of which is divided into 14 kalpas.
Each kalpa is divided into 14 manvantara (each 306,720,000 years). Two kalpas constitute one Brahma day and one Brahma night. A Brahma month contains 30 of these days including nights or 259.2 billion years.
According to the Mahabharata, 12 months of Brahma constitute one of his years and 100 of those years, the life cycle of the universe. Assume that 50 years of Brahmā have already elapsed and we are now in the shvetavaraha kalpa, which is number 51. At the end of a kalpa, the world disappears.
Raja yoga of the Brahma Kumaris world spiritual university.
For the raja yoga of Brahma Kumaris, the kalpa, the cycle of the world (non-linear) lasts 5000 years, that is, the history of the life of the soul on Earth is 5000 years, not a day more or a day less.
As souls that we are, and not bodies with souls, our Home is the Supreme Abode, Paramdham or Nirvana, there we reside with God, our Supreme Father Shiva, and then each one in his time descends to Earth to take a body, reincarnate, and thus populate this material world.
The Kalpa, the Cycle of the world lasts 5000 years tells us Shiva, our Supreme Spiritual Teacher, and is divided into 4 equal parts:
The golden age, the silver age (Satyuga or paradise both), with 2500 years of duration, and then comes the copper age (the time of the body religions, where the founders of the main body religions appear:
Muslim (by Mohamed), Buddhism (by Buddha), Jewish (by Abraham) and Christian by Christ, and the Iron Age, which is when the world reaches its maximum degradation at all levels.
It is at the end of the iron age, where The Supreme Soul, Shiva, descends to this corporeal world, taking a body incognito to many and gives all the knowledge of the true Raja yoga, The True Gita, so that before the destruction of the world His devotees (the whole world) will be nourished by Him and return to the forgotten Home, Paramdham or the Home of the souls, Nirvana.
The Guinness Book of Records lists the Kalpa of 4.32 billion years as the longest time measurement on record.