This work looks at the box-counting dimension of sets related to subordinators (non-decreasing Lévy processes). It was recently shown in Savov (Electron Commun Probab 19:1-10, 2014) that almost surely lim δ→0 U (δ)N (t, δ) = t, where N (t, δ) is the minimal number of boxes of size at most δ needed to cover a subordinator's range up to time t, and U (δ) is the subordinator's renewal function. Our main result is a central limit theorem (CLT) for N (t, δ), complementing and refining work in Savov (2014). Box-counting dimension is defined in terms of N (t, δ), but for subordinators we prove that it can also be defined using a new process obtained by shortening the original subordinator's jumps of size greater than δ. This new process can be manipulated with remarkable ease in comparison with N (t, δ), and allows better understanding of the box-counting dimension of a subordinator's range in terms of its Lévy measure, improving upon Savov (2014, Corollary 1). Further, we shall prove corresponding CLT and almost sure convergence results for the new process.