This paper proposes a novel methodology for the calculation and estimation of transmission line impedance with the use of real time data from synchrophasor measurement units. Current synchrophasor standards do not provide impedance data and must therefore be calculated. The algorithms used in this paper include impedance calculation, outlier detection and elimination as well as denoising using regularized least square estimation. The proposed methodology operates using a small sample size and can therefore be applied in real time to provide operators with instantaneous impedance values from transmission lines. The paper also investigates how changing several methodology parameters can affect the accuracy of the output obtained. The overall methodology as well as these parameters have been tested using real synchrophasor data from an American utility provider.