This paper presents the results of a comparative study conducted on fuel properties of optimal diesel-biodiesel-ethanol (DBE) blends. A nonlinear optimisation model formulated for DBE blending process with key fuel properties as constraints and solved using the Lingo optimisation software. The model established ideal blending ratio for DBE ternary fuel by maximising the net heating value (LHV) while meeting multiple fuel property constraints. Applicable fuel mixing rules were extrapolated from previous literatures for anticipating the properties of the ternary fuel blends. The model is executed at different scenarios by simultaneously varying the ethanol content in the blend and blending ratios were estimated. Further, the ternary fuel blends were prepared, and key fuel properties viz., density, cloud point, pour point, acid value, water content, calorific value, kinematic viscosity, oxidation stability and copper corrosion values were tested according to ASTM test methods and the results are discussed. All DBE blends with anhydrous ethanol was found to be completely stable while fuel blends with hydrous ethanol showed phase separation. Biodiesel acted as a good emulsifier with increase in its content in the blend, rectifying the phase separation problems caused by higher ethanol content in the blends. Ethanol had higher effect on DBE blends calorific value. The cloud point temperature did not to follow the Kay’s mixing rule precisely. All DBE blends found to satisfy the Thailand fuel standard for pour point with values less than 9°C. The density of fuel blends followed Kay’s mixing rule with minimum deviation. The density values of all BDE blends were within the range of 0.840 - 0.855 kg/m³, satisfying the Thailand fuel standard as well as the premium fuel quality standards. The acid value of DBE blends increased by roughly 3% - 7% for each 10% of biodiesel added volumetrically. All the blends found to have the acid value less than the ASTM limit of 0.3mg.KOH/g.