Srimad-Bhagavatam: Canto 3 - Chapter 1 - Verse 7

Sanskrit:

निमेषस्त्रिलवो ज्ञेय आम्नातस्ते त्रय: क्षण: ।क्षणान् पञ्च विदु: काष्ठां लघु ता दश पञ्च च ॥ ७ ॥

ITRANS:

nimeṣas tri-lavo jñeyaāmnātas te trayaḥ kṣaṇaḥkṣaṇān pañca viduḥ kāṣṭhāṁlaghu tā daśa pañca ca

Translation:

The duration of time of three lavas is equal to one nimeṣa, the combination of three nimeṣas makes one kṣaṇa, five kṣaṇas combined together make one kāṣṭhā, and fifteen kāṣṭhās make one laghu.

Purport:

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.