The escalating global population has spurred a significant surge in energy demand. While developed nations pivot towards renewable energy sources, many developing countries rely heavily on fossil fuels. Understanding these fuels' higher heating value and chemical exergy is crucial for energy analysis, second law analysis, optimal energy generation, and resource conservation.This study introduces an adaptable analytical method for calculating the higher heating value and chemical exergy of fossil fuels (coal, oil, natural gas). It demonstrates minimal error, with approximately a 3.5 % deviation for higher heating value and 8 % for chemical exergy compared to empirical relations.Novel relationships, developed through linear regression and computer programming, address research gaps and exhibit a maximum 2.6 % difference for higher heating value and 5.4 % for chemical exergy compared to existing empirical references. These contributions will greatly benefit energy professionals and engineers.This research addresses critical gaps in current methodologies for estimating higher heating value and exergy by offering a compact form for calculating various fossil fuels within a wide range of Carbon-to-Hydrogen ratios (3–105). Additionally, it provides specific equations applicable to both mole and mass fractions for natural gases, primarily composed of methane, with mole fractions ranging from 55 % to 99 %.