Yes, Series 11 has ECG and US blood oxygen. Full sensor list, ECG accuracy from the EQUAL trial, hypertension notification data, and how it compares to Ultra 3.
Short answers first: yes, the Apple Watch Series 11 has ECG. Yes, it has blood oxygen — including in the United States. It carries four core health-sensing systems plus a full motion suite, and its one genuinely new health feature over older models is hypertension notifications. This page answers every sensor question we get about the Series 11 in one place, with links to our deeper clinical-accuracy testing where it exists.
Source check: July 10, 2026. Details verified against Apple's published specifications, the 2026 EQUAL trial results, and the February 2026 JAMA study on hypertension notifications.
Does the Apple Watch Series 11 Have ECG?
Yes. The Series 11 records a single-lead electrocardiogram using electrodes built into the Digital Crown and the crystal on the back of the watch. Open the ECG app, rest your finger on the crown for 30 seconds, and the watch classifies your rhythm as sinus rhythm, atrial fibrillation (AFib), inconclusive, or poor recording. The recording method is unchanged from previous generations, but updated sensor hardware in the Series 11 reduces noise in the readings.
How Accurate Is the Series 11 ECG?
More validated than any other consumer wearable. The 2026 EQUAL trial found Apple Watch ECG increases atrial fibrillation detection by 4x compared with standard screening, with 94.8% sensitivity for AFib episodes. A 2025 meta-analysis in npj Digital Medicine comparing it to 12-lead clinical ECG found strong correlation, with a tendency to slightly underestimate QT interval duration. For rhythm classification — the thing you actually use it for — it is the benchmark.
We break down the full trial data in our guide to Apple Watch ECG accuracy and the EQUAL trial.
How Many Sensors Does the Series 11 Have?
Counting depends on what you call a sensor, so here is the honest breakdown. The Series 11 has four core health-sensing systems:
- Optical heart sensor — continuous heart rate, plus the pulse wave analysis behind hypertension notifications.
- Electrical heart sensor — the ECG electrodes in the Digital Crown and back crystal.
- Blood oxygen sensor — red and infrared LEDs with photodiodes measuring SpO2.
- Temperature sensor — wrist temperature while you sleep, used for cycle tracking and the Vitals app.
On top of that sits the motion and environment suite: high-g accelerometer (crash and fall detection), gyroscope, always-on altimeter, compass, ambient light sensor, GPS, and the microphone that enables noise monitoring and sleep apnea detection support.
Does the Series 11 Have Blood Oxygen — Including in the US?
Yes. After the Masimo patent dispute forced Apple to disable blood oxygen on US models in 2024, the feature returned via a redesigned implementation, and the Series 11 ships with blood oxygen monitoring available in the United States. Readings feed both the on-demand SpO2 app and background overnight measurements in the Vitals app. A healthy reading typically falls between 95% and 100%.
For what those numbers mean and how accurate the sensor is against pulse oximeters, see our blood oxygen guide and our SpO2 clinical accuracy testing.
What Is Actually New: Hypertension Notifications
The Series 11's headline health addition. Using pulse wave analysis from the optical sensor, the watch builds a profile of your vascular behavior over at least 14 days within a 30-day window and alerts you to patterns consistent with chronic high blood pressure. It does not measure blood pressure directly — no consumer wrist wearable does.
The honest numbers: Apple's internal study found the feature catches roughly 4 in 10 people with hypertension, rising past half for stage 2 hypertension. The February 2026 JAMA study found that when you get an alert, there is about a 70% chance you genuinely have hypertension. It works best as a passive screening tool for people who would otherwise never check.
Setup: Health app → Heart → Hypertension Notifications, then let it collect data passively. Our full Series 11 health review covers the enrollment flow and our real-world results.
What About Sleep Tracking and Sleep Apnea?
The Series 11 scores your sleep 0–100 (duration 50 points, bedtime consistency 30, interruptions 20), tracks Awake/REM/Core/Deep stages, and monitors breathing disturbances for patterns consistent with moderate-to-severe sleep apnea — an FDA-cleared over-the-counter screening feature, not a diagnosis. Wrist temperature, respiratory rate, overnight heart rate, and SpO2 all roll into the morning Vitals dashboard.
Series 11 vs Series 10 vs Ultra 3: Sensor Differences
The sensor hardware story is closer than the marketing suggests. The Series 10 has the same ECG, blood oxygen, and temperature sensing — it lacks hypertension notifications only where older optical sensor generations cannot support pulse wave analysis reliably. The Ultra 3 matches the Series 11's health stack and adds the depth gauge, water temperature sensor, and dual-frequency GPS for outdoor and dive use. If you are choosing purely on health sensing, the Series 11 gives you everything the Ultra 3 has.
Bottom Line: Is the Series 11 Worth It for Health Tracking?
If you are coming from a Series 9 or earlier, yes — hypertension notifications, the sleep score, and the quieter, more accurate optical sensor make it the biggest health-focused jump in several generations. From a Series 10, the case is thinner: you are upgrading for hypertension alerts and better battery. Either way, the Series 11 is currently the most clinically validated health wearable you can put on your wrist.
