... launch a few of you (rightly) asked how accurate reading heart rate from a webcam actually is. So I stopped hand-waving and measured it. Setup GlowPulse and a Polar H10 (chest-strap ECG, the practical gold standard) recording at the same time, second by second, across 9 sessions and ~3.5 hours total, in good light, dim light, movement, and dark. What I found Good light, sitting still: off by about 1 BPM from the strap