Let \(K=\mathbb {Q}(\theta )\) be a number field generated by a root \(\theta \) of a monic irreducible polynomial \(g(x) \in \mathbb {Z}[x]\) of degree n. We study the index of a number field, denoted by I(K), with a particular focus on its p-adic valuation \(\nu _p(I(K))\) . We construct infinite families of number fields for which the p-adic valuation of the index is explicitly determined. In particular, we demonstrate that for both \(p=2\) and odd primes, the value of \(\nu _p(I(K))\) can be arbitrarily large, irrespective of the degree n. Furthermore, we provide several examples to illustrate the results.