jain dharm ke anusar kalchakra ya kaal‑chakra ka badlav ek nishchit tithi par nahi hota. Yeh anek saalon, hazaron-pardon ya aur bahut bade samay ke baad hota hai — yani har kalchakra ke do arhon (utsarpini aur avasarpini) ke ant par. In donon half‑cycles ke ant par hi kalchakra ki navin gati shuru hoti hai.

• vartaman me hum avasarpini ke 5th arc (Duṣamā) mein hain, aur jab yeh avasarpini samapti hogi, tab phir se utsarpini (uttarārdh) shuru hoga. isliye kalchakra ki parivartan ki tithi ko ghatnaon ya samay‑sankhya ke roop mein kisi nishchit tareekh se jodna mushkil ya asambhav hai.
• Digambar aur Shwetambar dono paramparaon me is mool adhikar ko sweekar kiya gaya hai; dono hi is kaalchakra ki do padio ki awastha ko mante hain, halanki kuch granthiyon me ar ki sankhya ya vivaran thode se alag mil sakte hain.

Aap chahein to is vishay ki adhik saaf samajh ke liye yeh sthal padh sakte hain jahan Kalchakra ke vyakhya ka saransh milta hai: Understanding Jain Kalchakra (Time Cycle). You can read more here

Note: Agar aap chahen to main is topic se judi aur Jain shastriya vyakhya ke hisaab se aur vistrit points de sakta/ sakti hoon.