Logarithmic scale: each step up is ten times longer. Indian units are on the left, familiar durations on the right. Click or tab to a unit to read about it. Numbers between units show how many of one make the next.
Each unit is defined in the texts as a multiple of a smaller one. To give it a value in seconds, a chain has to be tied to a known length. For the small units of the Bhagavata Purana (3.11) the tie is the nadika: 60 of them make a day and night, so one nadika is 24 minutes, and every unit below it follows by division. The Surya Siddhanta (chapter 1) starts instead from the prana, the time of one breath or of ten long syllables, and builds up to the day; it then uses the day of the gods (one human year) to reach the yugas, the kalpa and the life of Brahma.
Values are shown as the texts' arithmetic gives them, rounded for display. They describe a traditional scheme of time, not measurements. The modern comparisons are approximate and are only there to give a feel for the size of each unit.
Sources: Bhagavata Purana, book 3, chapter 11; Vishnu Purana, book 1, chapter 3; Manusmriti, chapter 1 (verses 64–80); Surya Siddhanta, chapter 1 (verses 11–21), as translated by E. Burgess (1860). Spellings are simplified Roman with the Devanagari in brackets.