The surface roughness model in the turning of AISI 1040 carbon steel was developed in terms of cutting speed, feed rate and depth of cut, using response surface methodology and design of experiment. The surface roughness equations of cutting tools when machining the carbon steels were achieved by using the experimental data. The established equations show that the feed rate was the main influencing factor on the surface roughness and it increased with increasing the feed rate for both tools. For TiN-coated tools, the feed rate is followed by depth of cut. For cermet tools, however, the feed rate is followed by cutting speed. In addition, the cermet tools showed the better surface roughness than those of the coated cutting tools. The second order model shows that the square terms are statistically insignificant for both tools. For the cermet tools, however, the interaction terms are found to be statistically significant. The predicted wear behavior of the samples has been found to lie close to that of the experimentally observed ones.