In this work, we evaluate the accuracy of our cuffless photoplethysmography based blood pressure monitoring (PPG-BPM) algorithm. The algorithm is evaluated on an ultra low power photoplethysmography (PPG) signal acquired from the Senbiosys Ring. The study involves six male subjects wearing the ring for continuous finger PPG recordings and non-invasive brachial cuff inflated every two to ten minutes for intermittent blood pressure (BP) measurements. Each subject performs the required recordings two to three times with at least two weeks difference between any two recordings. In total, the study includes 17 recordings 2.21 ± 0.89 hours each. The PPG recordings are processed by the PPG-BPM algorithm to generate systolic BP (SBP) and diastolic BP (DBP) estimates. For the SBP, the mean difference between the cuff-based and the PPG-BPM values is -0.28 ± 7.54 mmHg. For the DBP, the mean difference between the cuff-based and the PPG-BPM values is -1.30 ± 7.18 mmHg. The results show that the accuracy of our algorithm is within the 5 ± 8 mmHg ISO/ANSI/AAMI protocol requirement.