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In a company-conducted 2026 comparison, Apple Watch Series 12 measured heart rate more accurately overall than Garmin Forerunner 970. The study compared both watches against a Polar H10 chest strap, but it was conducted by Apple—not independently replicated—and its result applies to those specific models and protocols, not every Apple Watch or Garmin.
What did the Apple Watch vs. Garmin study find?
Apple reported that Series 12 had statistically better heart-rate accuracy than Forerunner 970 for the study’s overall workout and daily-living protocols, using both mean absolute error (MAE) and root mean square error (RMSE). For session-average heart rate, Apple reported better accuracy in 11 of 12 overall comparisons; the exception was Huawei Watch 5 during workouts, where Apple’s numerical result was better but not statistically significant. These are Apple’s findings, not an independent adjudication. Apple’s September 2026 study did not provide a simple standalone MAE figure for the Series 12-versus-Forerunner 970 headline in its text, so a single beats-per-minute advantage cannot be stated from that account.
The result is a direct comparison of Apple Watch Series 12 and Garmin Forerunner 970 under Apple’s study conditions. It does not show that every Apple Watch is more accurate than every Garmin, or establish how these watches perform for every wearer and activity.
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Apple’s study ran in July and August 2026 at five sites in California, Texas, and Malaysia. Participants wore an Apple Watch and one comparison wrist device at the same time, with a Polar H10 ECG chest strap serving as the reference. The other comparison devices were Google Pixel Watch 4, Huawei Watch 5, Samsung Galaxy Watch 8, WHOOP 5, and Oura Ring 5. Wrist assignment was randomized; Apple Watch was worn on the dominant hand about half the time, and devices were fitted snugly according to manufacturers’ guidance. Apple’s study description covers the protocol and analysis.
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- A FULL-FEATURED HEALTH TRACKER—Apple Watch Series 11 gives you invaluable insights about your body, right from your wrist. Take an ECG anytime* and get alerts for a high and low heart rate or an irregular rhythm*—so you can stay closer to your heart. You can also view your overnight health tracking metrics with the Vitals app* and be notified of possible sleep apnea.*
- KNOW YOUR SLEEP SCORE—With advanced sleep tracking, Series 11 gives you a daily sleep score. It’s an easy way to help measure and understand the quality of your sleep, so you can make it more restorative.
- GET HYPERTENSION NOTIFICATIONS—Did you know that Series 11 can spot signs of chronic high blood pressure? By analyzing how your blood vessels respond to beats of the heart, it can notify you of possible hypertension.*
- SAFETY FEATURES—A smartwatch that puts your safety first. Series 11 can detect a hard fall or severe car crash, automatically help connect you with emergency services, and notify your emergency contacts.* Check In can automatically notify a loved one when you’ve arrived at your destination.
- A POWERFUL FITNESS TRACKER—With advanced metrics and motivating features like Pacer, Heart Rate Zones, training load, and Workout Buddy powered by Apple Intelligence from your nearby iPhone*—Series 11 is made to help everyone stay active, from runners and hikers to strength-training enthusiasts.
The workout protocol included outdoor running at different speeds, indoor interval treadmill running, outdoor cycling, HIIT, and strength training. Each activity lasted 15–20 minutes. A separate daily-living protocol covered rest, desk work, meal preparation, and walking. Apple aimed for at least 50 participants per workout activity per comparison device and used session-level MAE and RMSE, paired comparisons, and 99% confidence intervals.
Apple enrolled 1,460 participants; 1,254 contributed at least one paired Apple-versus-comparison measurement. Among final-analysis contributors, 20% had Fitzpatrick skin tone V or VI and 35% were female; mean age was 39 ± 12 years and mean BMI was 26 ± 5 kg/m². Apple reported that 59% enrolled at third-party contract-research sites. The study excluded people taking beta blockers and people with tattoos or large moles at device sites, which limits how broadly its results can be applied.
How strong is the evidence?
The study is unusually direct because it tested current named models side by side against a chest-strap reference across several activities. Its sponsor matters: Apple conducted the study and reported the results. No independent source in the available evidence has replicated the Series 12-versus-Forerunner 970 comparison.
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- A FULL-FEATURED HEALTH TRACKER—Apple Watch Series 11 gives you invaluable insights about your body, right from your wrist. Take an ECG anytime* and get alerts for a high and low heart rate or an irregular rhythm*—so you can stay closer to your heart. You can also view your overnight health tracking metrics with the Vitals app* and be notified of possible sleep apnea.*
- KNOW YOUR SLEEP SCORE—With advanced sleep tracking, Series 11 gives you a daily sleep score. It’s an easy way to help measure and understand the quality of your sleep, so you can make it more restorative.
- GET HYPERTENSION NOTIFICATIONS—Did you know that Series 11 can spot signs of chronic high blood pressure? By analyzing how your blood vessels respond to beats of the heart, it can notify you of possible hypertension.*
- SAFETY FEATURES—A smartwatch that puts your safety first. Series 11 can detect a hard fall or severe car crash, automatically help connect you with emergency services, and notify your emergency contacts.* Check In can automatically notify a loved one when you’ve arrived at your destination.
- A POWERFUL FITNESS TRACKER—With advanced metrics and motivating features like Pacer, Heart Rate Zones, training load, and Workout Buddy powered by Apple Intelligence from your nearby iPhone*—Series 11 is made to help everyone stay active, from runners and hikers to strength-training enthusiasts.
Across all 159 individual activity-by-measure comparisons in Apple’s study, Apple reported a statistically better result in 139, an indeterminate result in 18, and a better result for the comparison device in 2. Point estimates favored Apple in 155 of 159. Those totals span all comparison devices and activities; they are not a Garmin-only score.
Older independent evidence offers context, not a current-model verdict. A 2019 prospective study of 50 healthy athletic adults compared Apple Watch III, Garmin Vivosmart HR, Fitbit Ionic, and TomTom Spark 3 during treadmill running at six speeds. Against ECG, the study reported concordance of 0.96 for Apple Watch III and 0.89 for Garmin Vivosmart HR; the Polar H7 chest strap scored 0.98. Accuracy fell at high intensity. Because the watches were older models, these findings do not validate either Series 12 or Forerunner 970. The Journal of Sports Sciences study describes its methods and results.
A 2025 living systematic review of Apple Watch validation studies pooled heart-rate limits of agreement at about −7.19 to 6.64 bpm across all conditions. An exploratory subgroup for third-generation optical sensors—Series 6 onward, including Ultra—reported narrower limits of −3.68 to 2.59 bpm, based on eight studies. These pooled results combine different protocols and reference methods; they are not a direct comparison with Garmin or a Series 12-specific result. The review in npj Digital Medicine discusses that variation and notes that many included devices were discontinued.
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- GET SMARTER HEALTH INSIGHTS—Apple Watch SE 3 is an advanced health tracker that helps you better understand your body. The smartwatch sends alerts for an irregular heart rhythm, or an unusually high or low heart rate.* You can view your overnight health tracking metrics with the Vitals app,* track your sleep score, and get sleep apnea notifications.*
- A GREAT FITNESS TRACKER—SE 3 can track your workouts in a healthy number of ways—from running and strength training to simply achieving your 10K steps a day. With real-time metrics and Workout Buddy powered by Apple Intelligence from your nearby iPhone,* you’ll hit your goals like never before.
- KEEP HELP CLOSE AT HAND—SE 3 is a smartwatch that can detect a hard fall or severe car crash and automatically help connect you to emergency services and notify your emergency contacts.* Check In can automatically notify a loved one when you’ve arrived at your destination.
- WOMEN’S HEALTH INSIGHTS—SE 3 has advanced sensors that track your wrist temperature while you sleep. With this smartwatch, you can log your periods and symptoms, get period predictions, and get notified of cycle deviations.*
- GREAT BATTERY LIFE AND FASTER CHARGING—Enjoy a smartwatch with all-day, 18-hour battery life* from sunup to sundown. Then charge up to twice as fast as SE 2* and get up to 8 hours of battery in just 15 minutes.*
Why results can differ by activity and measurement method
Wrist heart-rate monitors use optical sensing, and their performance depends on the signal the sensor receives as well as how the device processes it. Apple says its optical sensor uses green LEDs and light-sensitive photodiodes to detect changes in blood flow at the wrist. Its support guidance gives an optical heart-rate range of 30–210 beats per minute and cautions that a reliable reading may not be available every time for every person. Apple’s heart-rate support page explains the sensor and factors that can affect readings.
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Apple’s 2024 technical paper says its heart-rate algorithms prioritize accuracy over availability and may withhold readings when sensor signals are inadequate. A gap in the displayed data therefore does not necessarily mean the watch recorded a particular incorrect value; it may mean the algorithm did not consider the signal reliable enough to report. Apple’s technical paper describes its approach and validation sessions with chest-strap or ECG ground truth.
When judging accuracy, keep these distinctions in view:
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- GET SMARTER HEALTH INSIGHTS—Apple Watch SE 3 is an advanced health tracker that helps you better understand your body. The smartwatch sends alerts for an irregular heart rhythm, or an unusually high or low heart rate.* You can view your overnight health tracking metrics with the Vitals app,* track your sleep score, and get sleep apnea notifications.*
- A GREAT FITNESS TRACKER—SE 3 can track your workouts in a healthy number of ways—from running and strength training to simply achieving your 10K steps a day. With real-time metrics and Workout Buddy powered by Apple Intelligence from your nearby iPhone,* you’ll hit your goals like never before.
- KEEP HELP CLOSE AT HAND—SE 3 is a smartwatch that can detect a hard fall or severe car crash and automatically help connect you to emergency services and notify your emergency contacts.* Check In can automatically notify a loved one when you’ve arrived at your destination.
- WOMEN’S HEALTH INSIGHTS—SE 3 has advanced sensors that track your wrist temperature while you sleep. With this smartwatch, you can log your periods and symptoms, get period predictions, and get notified of cycle deviations.*
- GREAT BATTERY LIFE AND FASTER CHARGING—Enjoy a smartwatch with all-day, 18-hour battery life* from sunup to sundown. Then charge up to twice as fast as SE 2* and get up to 8 hours of battery in just 15 minutes.*
- Exact model and sensor generation: findings for one watch generation do not automatically carry over to another.
- Activity: steady running, intervals, cycling, lifting, and everyday movement create different conditions for wrist sensing. A 2026 validation study of other wearable models found that intermittent walking increased error for multiple devices; it did not test Series 12 or Forerunner 970. That study’s findings reinforce that results can vary by activity.
- Point-by-point versus session average: a device may track the overall level during a workout differently from how closely each individual reading follows the reference.
- Accuracy versus availability: a device that reports fewer readings may avoid showing values when its signal is poor. Compare the displayed data stream, not accuracy alone.
- Response lag and reporting interval: rapid changes can expose delays, and devices may report at different intervals. Apple’s comparison evaluated user-facing data streams, which can differ among devices.
Should you use a chest strap instead of wrist heart rate?
If close tracking during training is a priority, a chest strap such as the Polar H10 is a relevant option: it was the reference device in Apple’s 2026 comparison, and a Polar chest strap was also closest to ECG in the 2019 athlete study. That does not make a strap mandatory. The right choice depends on how much you value training data, how comfortable you find a chest strap, and whether your wrist device gives readings that are useful for your workouts.
Apple Watch Series 4 and later, and all Ultra models, also include electrical electrodes used by the Heart Rate and ECG apps. That is a separate feature from continuous optical monitoring during workouts; ECG capability should not be confused with the optical sensor’s ongoing heart-rate tracking. Apple’s support information explains the distinction.
Quick Recap
What to take away
- Apple’s September 2026 head-to-head study found Series 12 more accurate overall than Forerunner 970 under its tested protocols, with a Polar H10 as the reference.
- The result is company-conducted and model-specific; independent replication of that exact comparison is not established.
- Older independent testing and broader validation reviews support treating activity, measurement method, and sensor generation as important context—not as proof of a current-model ranking.
- Wrist heart-rate data is useful for training feedback, but it should not be treated as a medical diagnosis.
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