Broadband ferromagnetic resonance (bbFMR) spectroscopy is an established experimental tool to quantify magnetic properties. Due to frequency-dependent transmission of the microwave setup, bbFMR measurements in the frequency domain require a suitable background removal method. Here, we present a measurement and data analysis protocol that allows us to perform quantitative frequency-swept bbFMR measurements without the need for a calibration of the microwave setup. We furthermore compare the results of the proposed frequency space analysis and a conventional analysis in field-space of bbFMR data obtained from a permalloy thin film. The very good agreement of the extracted parameters using the two methods shows the reliability of our method.