Leaf nutrient levels are traditionally quantified by laboratory chemical analysis, which is time consuming and requires huge investment. The objective of this research is to estimate the nutrient content of groundnut leaves using an assembled visible near-infrared spectroradiometer (650-900 nm). This method is faster and requires less time and investment compared to conventional chemical analysis. Different fertilizer was applied for different conditions along with one control of groundnut plants. The nutrient deficiency in the groundnut plants was created artificially. The leaf samples were collected in the growth of different days. The samples were analyzed for major nutrient concentrations, which are acquired by field conditions. This research provides the guidelines on the nutrient estimation of the groundnut leaves. The peak reflectance esteem was seen in the infrared range (650-900 nm) and the reflectance value was observed for nitrogen (716 nm), phosphorus (737 nm), and potassium (720 nm). This study may provide guidelines for estimating macronutrients and yield estimation of groundnut plants.