A bstract By applying the Covariant Entropy Bound (CEB) to an EFT in a box of size 1 / ΛIR one obtains that UV and IR cut-offs are necessarily correlated. We argue theory Quantum Gravity (QG) should identify cutoff with ‘species scale’, give general algorithm calculate it case multiple towers becoming light. One then upper bound on characteristic mass scale tower terms cut-off, given by M ≲ $$ ...