A Hom-Lie algebra pL, α L q is said to be capable if there exists a Hom-Lie algebra pH, α H q such that L -H{ZpHq. We obtain a characterisation of capable Hom-Lie algebras involving its epicentre and we use this theory to further study the six-term exact sequence in homology and to obtain a Hopf-type formulae of the second homology of perfect Hom-Lie algebras.