Peppers (Capsicum annuum L.) are an important horticultural crop and are used fresh and processed. Fruit size estimation is used to describe the fruit’s growth curve, monitor individual plant growth, predict yield, and conduct physiological studies. Water displacement techniques are used to determine fruit volume, but these are time-consuming and impractical under field conditions. The aim of this study was to devise a mathematical model to analytically determine the non-destructive pepper fruit volume. Fruit volume was described as a dependent variable, while length, weight, and diameter were independent variables in the model which was formulated as Yi = 19.226859 + 0.139562 Xi - 0.256142 Zi + 1.429122 Ti, where Yi = fruit volume (cm³), and Xi, Zi, and Ti are fruit diameter (mm), length (mm), and weight (g) , respectively. This equation can be easily used to predict the accuracy of pepper fruit volume. A significant relationship (P ≤ 0.01) was found between dependent and independent variables. The correlation coefficient describing the relationship between the actual fruit volumes and the model solution was 0.9516. Consequently, it was determined that pepper fruit volume can be described as depending on fruit length, weight, and diameter.