We develop an algorithm to measure densely-spaced vertical offsets along a scarp-like feature, and apply it to end-glacial fault-scarps (EGFs) in Fennoscandia, a stable-continental region (SCR). We find significant variability in apparent vertical offsets, and develop an equation to estimate the uncertainty (1σ) for a given average offset and number of measurements. We calculate the slip-to-length ratios for the faults, assuming their fault-scarps were formed in a single earthquake, and find that these ratios are up to ten times higher than found in rapidly deforming regions, which have been more studied. We find potential magnitudes of the earthquakes that formed these scarps were M7-8.2. We suggest that slip-variability along ruptures could be higher than often assumed, which means paleoseismological results should have larger uncertainty, but reduces in a predictable way with increase in number of measurements, and at least 5 measurements should be taken. We also suggest that the slip-to-length ratio used to simulate earthquakes in SCRs should be 7.5±2x10^-5, in comparison with the Wells and Coppersmith value of roughly 2±0.5x10^-5.