Carbon (C) and nitrogen (N) determination with traditional methods is more laborious and time-consuming than automated analyzers. Microprocessor-based technologies led to the development of automated analyzers and have reduced the time of analysis. However, these need to be standardized with respect to weight and mesh size of plant/organic material sample used. For standardization of Vario EL III carbon (C), hydrogen (H), nitrogen (N), and sulfur (S) analyzer for the particle size and amount of sample, laboratory studies were carried out for C and N determination by CHNS analyzer in comparison to the traditional methods for different categories of organics such as green manure (cowpea), crop residues (rice straw), animal residues (farmyard manure), and industrial by-product (press mud). Organic samples of <0.25-mm size resulted in greater amounts of C and N with both CHNS analyzer and traditional methods than with other size groups. The C and N contents were greater with a sample weight of 5 than with 10 mg.