Slabs are required to support a load concentrated over a small area relative to the size of the slab, which may arise from equipment, plant, safes or the like. For a one-way slab, a strip of width called effective width (beff) is considered to be effective in carrying the load to supports and is used to determine the requisite longitudinal flexural capacity of a single span one-way slabs. Based on a mixture of simplified analyses, test data and experience rules are given in various country building codes to determine widths of solid slabs effective for bending resistance of point and line loads. Alternatively, building codes also allow utilization of finite element analysis and design of slabs subjected to concentrated or line loads. In this study, finite element method was utilized to develop empirical effective width equation that account additional parameters that are not considered in the current effective width formula. ABAQUS/standard software was used for three dimensional nonlinear modeling of one way slab under concentrated load. The reinforcement bars were modeled as elastic-perfectly plastic material, the slab using concrete damage plasticity material model and the loader and support were assumed as rigid materials. Both material and geometric nonlinearity were taken into account. The results obtained from the finite element analysis were verified against experimental result of other researchers. Parametric study was performed to study the effective width of a one way slab by varying the slab width ratio, loader distance to span ratio and loader dimension. The result from the numerical method is comparable with that of the British and Indian standards. On average the result from numerical study is 1% and 4% greater than the British and Indian standard respectively. For all finite element models considered larger load widths would give larger effective width similar to analytical formulas. When the slab width ratio (Ly/Lx) decreases the numerical result shows that the effective width decrease significantly. Larger load length would result in larger effective width unlike analytical formulas which completely ignored the effect. Also both the concrete grade and slab thickness effect on the effective width was not significant. Finally nonlinear equation were generated after considering different combination of parameters using NCSS statistical software. Key words: Effective width, concentrated load, finite element method, Abaqus, concrete damage plasticity mode