The goal of this study is to produce precise correlations for computing the Colburn 'j' factor and fanning friction factor 'f' for plain triangular fins used in compact heat exchanger. Colburn 'j' factor is used for calculating heat transfer coefficient whereas fanning friction factor 'f' is used for calculating pressure drop across fin. Both are important to know while doing rating and sizing of a compact heat exchanger. Compact heat exchangers are known for having heat transfer area per unit volume greater than 700 (m²/m³). The numerical model chosen for this investigation is a plain triangular fin composed of 'aluminum' with 'air' as the fluid medium. For the purpose of creating the correlation, 1024 cases are run on 'Ansys Fluent' by altering fin height 'h', fin spacing 's', and fin thickness 't'. Sweep method is used for meshing the geometry and Realizable k epsilon model is used for turbulent region. The analysis covers both the laminar region (300 <= Re <= 2000) and the turbulent region (3000 <= Re <= 12000) over a wide range of Reynolds Numbers 'Re'. The correlations presented in this paper can be used to calculate the Colburn 'j' factor and fanning friction factor 'f' for any practical applications as it has a coefficient of determination around 95%. With the help of experimental data available in Kays & London [1] the correlations have been verified and validated. The correlations available in open literature for triangular fin are having huge differences compared with experimental results available in Kays & London [1]. This work is an attempt to make accurate correlations. Since experimental results are available for standard dimensions only, it is important to make accurate correlations for designing entire range of applications and as it would save lots of time and money.