LAB Fit is a software for Windows developed for treatment and analysis of experimental data. You are able to Treat similar data (grouped and ungrouped dataset, one or two samples); Treat non-similar data; Determine propagated error (error propagation up to eight independent variables); Plot 2D and 3D graph (normal, parametric, imported dataset, contour of maps); Execute math calculations; Extract data (x;y) from a 2D graph (digitizing); and Curve Fit. It has a menu for curve fitting and the main programs of this menu use nonlinear regression. It fits functions of one and several independent variables (from 1 up to 6), admitting uncertainties at the dependent variable (Y) and also at the independent variables (X). At the library there are more than 200 functions of one independent variable and almost 280 functions with two independent variables. The user disposes of a finder functions program.