SB 3.11.7
nimesas tri-lavo jñeya
amnatas te trayah ksanah
ksanan pañca viduh kastham
laghu ta dasa pañca ca
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The duration of time of three lavas is equal to one nimesa, the combination of three nimesas makes one ksana, five ksanas combined together make one kastha, and fifteen kasthas make one laghu.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
By calculation it is found that one laghu is equal to two minutes. The atomic calculation of time in terms of Vedic wisdom may be converted into present time with this understanding.