The KISSsoft System Module is a user-friendly tool also for load spectrum calculation designed for gearboxes. It incorporates nominal boundary conditions, variable forces on shafts, gear shifts, and hence changes in the power flow and operating mode variations. This complexity allows comprehensive calculations based on actual operating data, such as vehicle simulations or in situ measurements. This is particularly valuable for hybrid drive transmissions, continuously variable transmissions, and considering driving vs. coasting operation. For all bins in the load spectrum, the power losses are calculated, informing about the transmission efficiency. Each load case in the spectrum also serves as a nominal load for a single load calculation. Detailed reports for gears, bearings, and shafts clearly present key data, while the software supports easy export of load data for in-depth component analysis. Its intuitive interface ensures fast, accurate, and reliable calculations while saving engineer's time.