<p>Soil erodibility (K) is the intrinsic resistance of a soil to erosion which is a key factor required in soil erosion modeling and other process based models across the world. Soil erosion is a major problem in Ethiopia and estimation using models can help decision makers for interventions. But our K factor determinations in models have limitations and yet rare study has been done to determine K on process based approach. Disturbed soil samples of the five major soil types of Upper Blue Nile Basin, Ethiopia (Guder and Aba Gerima watershed) were collected from the field. Runoff plots’ using simulated rainfall was used to determine K values of soil. Rainfall simulator was used to generate runoff and sediment concentration data from the soils in one- hour simulated rainfall events, and an optical disdrometer was used to characterize the erosivity of the events. The results indicated that the K values of major soil types of the study area ranged between 0.046 to 0.140 t ha hMJ⁻¹mm⁻¹ha⁻¹. The lower K values was obtained in both Chromic Vertisols and Lithic Leptosols and were significantly (<i>P</i> &lt; 0.05) different from the other soil types. However, statistically insignificant differences were observed in K values among the Cambisols, Haplic Acrisols and Chromic Luvisols. The mean K value of the Haplic Acrisols was 0.14 t ha hMJ⁻¹mm⁻¹ha⁻¹ and ranged from 0.04 to 0.32, whereas the K value of the Chromic Vertisols ranged from 0.03 to 0.08 t ha hMJ⁻¹mm⁻¹ha⁻¹ with a mean value of 0.05. These results have important implications as potential replacements to the use of K values obtained from soil color and nomograph method.</p>