<p>Sandy soils are utilized for agricultural purposes in various regions worldwide due to the rapid increase in the global population. To overcome the challenges posed by sandy soil in agriculture, biochar is widely used to retain moisture and nutrients, thereby improving crop yields. However, due to the increasing scarcity of land, these agricultural areas are now being repurposed for construction. Consequently, the effect of biochar on the engineering properties of soil remains a pertinent question that has not been thoroughly investigated. This research aims to investigate influence of biochar on the mechanical characteristics of biochar amended sands. The biochar content and the particle size of biochar was varied to examine the influence of biochar particle size and content on the engineering characteristics of the biochar amended sand. The mean particle size ratios of the sand with biochar was ranging from 4.75 to 0.35 and the biochar content is varied from 0% to 40%. The influence of relative density is studied by varying it from 40% to 60% and 80%. The biochar amendment reduced the density of the biochar-sand mixture and modified the void ratio of the sand-biochar skeleton. Water retention improves across all mixes with different size ratios. The shear strength of the sand also improved with the incorporation of biochar, with peak strength observed at 20% addition, reaching 1.5 times that of sand for mixes with a mean particle size ratio of 4.75 and 1.2 times that of sand for mixes with a mean particle size ratio of 1.42. The shear strength of sand-biochar mixture with a mean particle size ratio of 0.35 improved up to 5% addition, with the peak strength being 1.4 times that of sand.</p>