CalcUS makes it easier for beginners to learn practical computational chemistry by providing all the tools required to launch, monitor and analyze calculations in a simple web interface. For example, input structures can directly be draw in a 2D sketcher. The result of the conversion to 3D can be inspected in the same interface, before launching the calculation. This eliminates the need for a 3D molecular editor and accelerates the input creation in many cases. In cases where the 2D sketcher does not do justice to the desired input structure, molecular structures can be uploaded in any of the standard formats, such as XYZ, MOL, MOL2 or SDF formats. Raw Gaussian output files can also be uploaded directly; CalcUS will parse the last structure of the files and use them as input.