I don’t think current understanding of things is that the universe is infinite. We can estimate the size of the universe we know, because we know how fast it is spreading and for how long. Wiki says: "Some disputed estimates for the total size of the universe, if finite, reach as high as 10 10 10 122 10^{10^{10^{122}}} megaparsecs. We don’t know whether that’s all there is though. We don’t even know whether the universe has the same properties everywhere, which complicates things.