New correlations for the air-side pressure drop and heat transfer coefficient (HTC) of slit and louver fin heat exchangers with 3-5 mm outer diameter tubes were developed based on Computational Fluid Dynamics (CFD) simulations of small, symmetric fin sections using Design of Experiments (DOE) techniques. The prediction accuracy of these CFD-based correlations was validated by experimental testing of 16 unique 5 mm slit and louver fin heat exchangers under a range of air velocities. The experimental results indicate that the proposed CFD-based correlation with correction factors for air-side pressure drop can predict 100% of the experimental observations with 20% error or less. After a new data reduction procedure accounting for fin conduction was implemented and a single correction factor applied, the HTC correlations could predict 98% of accepted test data with 20% error or less regardless of fin type.