TL;DR
- Chest strap: the reference. ECG straps agree with clinical ECG almost perfectly (concordance 0.996; MAPE 1.3-3.7%).[1][6]
- Armband: close behind. An upper-arm optical sensor erred by 1.43 bpm against a Polar H10.[5]
- Wrist: fine on average, unreliable reading by reading. Average error of about 1-6 bpm, with single readings up to about ±15 bpm from the strap and the worst results on the elliptical with arm levers.[1][2][5]
- Price is no tiebreaker: the Polar H10 strap and Verity Sense armband both cost $104.95.[3][4]
Chest strap vs optical heart rate: the strap is more accurate, an arm-worn optical sensor comes close, and a wrist sensor is accurate on average but can miss single readings by about 15 bpm.[2][5] This comparison uses two Polar sensors at the same price, the H10 chest strap and the Verity Sense armband, plus the validation studies that measured all three placements against ECG.
How do the Polar H10 and Verity Sense compare on paper?
| Spec | Polar H10 (chest strap) | Polar Verity Sense (optical) |
|---|---|---|
| Sensor type | Single-lead ECG (electrical)[3] | Optical (PPG)[4] |
| Worn on | Chest[3] | Arm or temple[4] |
| Price (US) | $104.95[3] | $104.95[4] |
| Connectivity | Bluetooth LE + ANT+, dual Bluetooth[3] | Bluetooth + ANT+[4] |
| Onboard memory | One session, up to 30 h[3] | Up to 600 h[4] |
| Power | CR2025 coin cell, up to 400 h[3] | Rechargeable, up to 30 h per charge[4] |
| Water rating | WR30[3] | WR50[4] |
| Subscription | None | None |
Why do chest straps and optical sensors diverge?
A chest strap measures the heart's electrical signal directly, the same signal a clinical ECG reads, so it registers each beat as it fires.[3] An optical sensor infers heart rate from changes in reflected light as blood pulses under the skin. That signal is disturbed by movement, a loose fit and poor blood flow, and the device smooths it over several seconds, so it reacts late to sudden changes. The wrist moves more than the upper arm, which is why placement matters as much as the technology.
How big is the accuracy gap in the studies?
| Placement | Study | Result against the reference |
|---|---|---|
| Chest (Polar H7) | Gillinov 2017[1] | Concordance 0.996 with ECG |
| Chest (Polar H10, Garmin HRM-Pro) | Merrigan 2023[6] | MAPE 1.28-3.73% vs ECG |
| Upper arm (Polar Verity Sense) | Schweizer 2025[5] | MAE 1.43 bpm vs Polar H10 |
| Upper arm (Polar Verity Sense) | Merrigan 2023[6] | MAPE 1.84-5.36% vs ECG |
| Wrist (Polar Vantage V2) | Schweizer 2025[5] | MAE 6.41 bpm vs Polar H10 |
| Wrist (optical monitor) | Sartor 2018[2] | MAE 3 bpm or less; limits of agreement within ±15 bpm |
| Wrist (Galaxy Watch 6) | Inoue 2026[7] | Bias -2.67 bpm; limits of agreement -16.9 to +11.6 bpm |
| Wrist (Apple Watch, Garmin Forerunner 235, Fitbit Blaze) | Gillinov 2017[1] | Concordance 0.92, 0.81 and 0.67 |
The activity matters as much as the device. In Gillinov 2017 every device did well on the treadmill except one, only three were acceptable on the bike, and none met the threshold on an elliptical with moving arm levers.[1] The deeper study-by-study review is in how accurate is wrist heart rate.
Which should you buy?
- Intervals, HIIT, rowing or elliptical work: the Polar H10 chest strap, which keeps pace with rapid changes and arm-driven movement.[1][3]
- You cannot stand a chest strap, or you swim: the Polar Verity Sense, which comes close to the strap on the upper arm and can sit at the temple on goggles.[4][5]
- HRV or research-grade data: the chest strap.[3]
- Choosing between full devices: read the best heart-rate monitors roundup, and for Polar vs Garmin straps the Polar vs Garmin accuracy comparison.
How do you make the reading trainable?
Whichever sensor you pick, the number only means something against your training zones. The Zone 2 Heart Rate Calculator returns the beats-per-minute band for low-intensity aerobic work, and the Heart Rate Zone Calculator builds the full five-zone spread for intervals and tempo.
Verified as of 2026-10-11. Prices are Polar's US list prices on that date and vary by retailer.
Frequently asked questions
Is a chest strap more accurate than an optical heart-rate sensor?
Yes. In a 50-person ECG comparison the Polar H7 chest strap agreed with ECG almost perfectly (concordance 0.996), ahead of every optical watch and band tested (0.67-0.92).[1] Chest straps from Polar and Garmin stayed within 1.3-3.7% of ECG in a newer head-to-head.[6]
How far off can a wrist sensor be?
Average errors of a few bpm hide much larger single-reading misses. Wrist optical monitors averaged 3 bpm or less of error in one large study, but individual readings ranged up to about ±15 bpm from the strap,[2] and a 2026 maximal-test study found limits of agreement of -16.9 to +11.6 bpm.[7]
Is an arm-worn optical sensor as accurate as a chest strap?
Nearly. The Polar Verity Sense on the upper arm erred by 1.43 bpm against a Polar H10, while the same sensor technology on the wrist erred by 6.41 bpm.[5] In a separate protocol the Verity Sense posted MAPE 1.84-5.36% against ECG, close to the chest straps.[6]
Which is better for HRV and recovery tracking?
A chest strap. Heart-rate variability needs precise beat-to-beat timing, which an ECG strap measures directly and an optical sensor can only infer from blood flow.[3]
Polar H10 or Polar Verity Sense: which should I buy?
Both cost $104.95 at Polar.[3][4] Choose the H10 for HRV, intervals and the closest match to ECG; choose the Verity Sense if a chest strap is uncomfortable or you swim, since it can also be worn at the temple on goggles.
References
- 1 Variable Accuracy of Wearable Heart Rate Monitors during Aerobic Exercise (Gillinov et al.) — Medicine & Science in Sports & Exercise, 49(8):1697-1703 (Polar H7 strap, four watches and a forearm optical band vs ECG on treadmill, bike and elliptical) (2017)
- 2 Wrist-worn optical and chest strap heart rate comparison in a heterogeneous sample of healthy individuals and in coronary artery disease patients (Sartor, Gelissen, van Dinther, et al.) — BMC Sports Science, Medicine and Rehabilitation, 10:10 (2018)
- 3 Polar H10 Heart Rate Sensor — official specifications and price ($104.95, single-lead ECG, Bluetooth LE + ANT+) — Polar (2026)
- 4 Polar Verity Sense optical heart rate sensor — official specifications and price ($104.95, arm or temple, Bluetooth + ANT+, 600 h memory) — Polar (2026)
- 5 Wrist-Worn and Arm-Worn Wearables for Monitoring Heart Rate During Sedentary and Light-to-Vigorous Physical Activities: Device Validation Study (Schweizer, Gilgen-Ammann) — Polar Vantage V2 wrist and Verity Sense arm vs Polar H10 — JMIR Cardio, 9:e67110 (2025)
- 6 Validation of Garmin and Polar Devices for Continuous Heart Rate Monitoring During Common Training Movements in Tactical Populations (Merrigan, Stovall, Stone, Stephenson, Finomore, Hagen) — Measurement in Physical Education and Exercise Science, 27(3):234-247 (2023)
- 7 Heart Rate Estimation Using the Galaxy Watch During Maximal Cardiopulmonary Exercise Testing: Cross-Sectional Validation Study (Inoue et al.) — JMIR Cardio, 10:e81917 (2026)