This study begins with a review of existing emissions prediction methodologies for Rich-burn Quick-quench Lean-burn combustors. The need for a simple and adaptable NOx emissions correlation for such combustor designs as used in state-of-the-art civil turbofan engines is discussed. The derivation of a new correlation is consequently presented. The proposed model is computationally inexpensive and sufficiently accurate for use in aero-engine multi-disciplinary conceptual design tools. Furthermore, it is possible to adapt the correlation to model the NOx emissions of combustors designed for very aggressive future cycles. A case study is presented focusing on the NOx performance of advanced future cycles relative to current and future certification limits.