Effects of the particle size (i.e. 100, 150, and 500 µm) and composition of biomass on physicochemical and mechanical properties of briquettes were evaluated. This study used biomass from the mixture of tofu dreg (TD), areca nutshell (ANS), and citronella (CN). This study was also completed with a literature review. ANS was carbonized at 250°C for 2 hours. Then, all raw materials (i.e. TD, ANS, and CN) were dried, saw-milled, and mixed with tapioca starch as a binder to form a dough. The particle size and ANS composition gave an impact on the briquettes' performance, including burning rate, specific fuel consumption, and mechanical properties. Particle size influenced the compact component in the briquette. ANS affected carbon and moisture contents in the briquette, improving its compressive strength. This study demonstrates the alternative solution for reducing organic wastes by converting them into briquettes.