An analytical method is used to calculate the spacing and width of cracks for a series of reinforced concrete beams having different material and sectional properties. The calculated values are used to investigate the effects of different variables on the spacing and width of cracks. Bar diameter, effective width of the beam per bar, concrete cover and the effective depth are shown to be the most significant parameters affecting the spacing and width of cracks at a given load level. A parametric study is subsequently carried out utilising the above significant parameters, and the spacing and width of cracks are re-calculated. Results of this parametric study are used to develop simplified prediction formulae. Finally a comparative study is undertaken, which indicates that the spacing and width of cracks calculated by the new formulae agree well with the test results of other investigators