Understanding the effects of blending biodiesel and diesel and predicting the density of the final blending fuel are key factors in selecting the appropriate blend for the final product. Additionally, the blending ratio has a significant role in determining the economic viability of the final fuel [16; 22]. As a result, knowing fuel density as well as other parameters under different circumstances is crucial for forecasting and enhancing engine performance [23]. It should also be noted that modelling is a powerful tool that allows for the prediction, optimization, and management of complex systems and processes in a wide range of applications. Through the creation of models, we can analyze the individual parts of a system and understand how they interact with each other. Furthermore, models are used to predict the behaviour of systems under different conditions. This is useful for predicting the effects of changes and evaluating different scenarios. Moreover, modelling enables hypothesis testing and experimentation without the need for expensive or risky real-world trials. Ultimately, models contribute to process and system optimization, facilitating more informed and effective decision-making. Based on the above, in recent years, research activity in the direction of the theoretical calculation and/or estimation of diesel/biodiesel blend properties has significantly developed. As an eco-friendlier option, the growing demand for biodiesel drives up the need for even higher fuel quality. [PERSON] et al. [24], in order to estimate combustion engine performance, determined some key fuel properties under various pressure and temperature conditions, with a particular focus on the density and viscosity of the mixtures. Their experimental data on density were obtained by blending diesel with 10% and 20% biodiesel (sunflower), with a temperature range of 293-413 K and a pressure of 0.1-60 MPa. In addition, [PERSON] et al. [18] studied whether the physicochemical properties, such as density and temperature, of blending diesel with vegetable biodiesel (corn) affect the fuel properties. The blends (5% to 75% biodiesel) were prepared on a volume basis, and the densities were measured in the temperature range of 10-40 \({}^{\circ}\)C. The properties of vegetable biodiesel and its blends were evaluated by determining other important properties, such as flash point temperature and the highest temperature value. The study performed by [PERSON] and [PERSON] [25] developed a comprehensive combustion model for biodiesel-fueled engine simulations. This model was designed for multidimensional simulations and incorporates realistic physical properties into an exhaust model, which involves multicomponent fuel sprays. In addition, an improved mechanism for biodiesel combustion chemistry is implemented. The study of [PERSON] et al. [26] investigated the enhancement of compression ignition engine performance using various biodiesel blends. The research utilizes modelling and optimization techniques to assess key engine performance parameters, including brake torque, brake-specific fuel consumption, and brake thermal efficiency, while taking into account different biodiesel blend ratios. A recent study by [PERSON] et al. compared the physicochemical properties of two types of biodiesel (eucalyptus and a blend of palm oil with limone) to conventional diesel,using mathematical models and experimental tests. The study developed a comprehensive analysis of the advantages and disadvantages of using biodiesel as an alternative to conventional fuels [27]. This paper examines how the increase in biodiesel fraction in diesel/biodiesel blends can affect the physicochemical characteristics of the fuel, maintaining the economic and environmental benefits. Therefore, the objective of the current study was to use a mathematical modelling tool that would be able to predict fuel properties, such as density and specific gravity, under various temperature conditions and biodiesel volumetric portions.