How is post-stroke walking performance assessed? While walking speed is commonly used, it may not be sufficient for tailoring individualized treatment plans. Recent reports highlight a strong connection between post-stroke walking performance and lower limb angles. However, many of these studies use advanced technologies that are not readily available for immediate clinical use. In our study, we utilized smartphones to capture and calculate lower limb angles during walking in post-stroke individuals. Surprisingly, our findings align with previous research, even using a method that clinicians can readily implement. We discovered a significant correlation between lower limb angles and walking speed. Additionally, although the relationship was weaker, the asymmetry in lower limb angles among post-stroke individuals also correlated with walking speed. These results suggest that assessing lower limb angles during post-stroke walking provides a valuable estimate of walking performance. Moreover, if lower limb angles are found to be small, planning interventions to increase them may be a justifiable approach to improving walking performance in post-stroke individuals.