There is growing interest to optimize the fused filament fabrication process to produce quality products and make it more energy efficient. One of the ways to help achieve this is by initially obtaining accurate build time and mass estimates from 3D printing slicer software to assess the energy consumed by 3D printers. This paper aims to compare the accuracy of build time and mass estimates of three different slicer programs, including Simplify3D, Cura and PrusaSlicer, through experiments for certain parameter settings. An Ultimaker 3 and Prusa i3 MK 3S+ printer are used for the estimates and actual experiments. The mean absolute error for each slicer software is quantified and the results are compared to assess accuracy. The mean absolute error of the build time estimate for Simplify3D, Cura, and PrusaSlicer was 55.25 min, 49.5 min, and 203.25 min, respectively. The mean absolute error of the mass estimate for Simplify3D, Cura, and PrusaSlicer was 4.49 g, 6.25 g, and 9.07 g respectively. The results show that slicer software tend to overestimate mass, while over or under predicting build time, depending on the printer and process parameters. Simplify3D and Cura provide the most accurate build time and mass estimates. The results indicate that Simplify3D and Cura estimates show promise for use in energy efficiency and material consumption analysis.