The Apple Watch Series 11 can record heart rate, blood oxygen saturation, and even generate ECGs. The latest version is also said to detect high blood pressure when worn consistently. While it doesn’t directly measure blood pressure, it reportedly estimates it through secondary cardiovascular indicators. (We’ve covered this feature in a dedicated article.)
To better evaluate accuracy, we compared the Watch’s readings with those from reference devices. For heart rate testing, we used a Polar H10 chest strap. At rest, the readings differed by only one beat per minute – an error margin of just 1.56 percent.
We also measured heart rate during activity at three different times. On average, the deviation was only 0.4 percent, with the largest single discrepancy being two beats per minute; two of the three measurements were identical. (We’ve compiled a detailed overview of smartwatch measurement accuracy separately.)
Blood oxygen saturation was tested three times as well, using a Braun Pulse Oximeter 1 as the reference device. The average deviation across the tests was 1.7 percent, with a maximum single difference of 2 percentage points. Interestingly, the Watch’s readings were consistently higher than those of the reference device.