The paper introduces BoltzTraP, a Fortran90 code designed to calculate band-structure dependent quantities, particularly semi-classic transport coefficients. The method relies on a smoothed Fourier expansion of the band energies, maintaining space group symmetry through the use of star functions. This approach allows for the calculation of derivatives necessary for transport distributions, such as conductivity, Hall effect, and thermopower. The code has been tested against earlier calculations based on Boltzmann theory, showing very good agreement. The method is particularly useful for complex materials and can be easily interfaced with other band-structure codes. The paper includes detailed implementation details, test cases (e.g., Bi2Te3 and CoSb3), and a comparison with experimental results, demonstrating the method's reliability and accuracy.The paper introduces BoltzTraP, a Fortran90 code designed to calculate band-structure dependent quantities, particularly semi-classic transport coefficients. The method relies on a smoothed Fourier expansion of the band energies, maintaining space group symmetry through the use of star functions. This approach allows for the calculation of derivatives necessary for transport distributions, such as conductivity, Hall effect, and thermopower. The code has been tested against earlier calculations based on Boltzmann theory, showing very good agreement. The method is particularly useful for complex materials and can be easily interfaced with other band-structure codes. The paper includes detailed implementation details, test cases (e.g., Bi2Te3 and CoSb3), and a comparison with experimental results, demonstrating the method's reliability and accuracy.