TL;DR
- For raw heart-rate accuracy, the Polar H10 and Garmin HRM-Pro Plus are effectively tied. The one peer-reviewed protocol that tested them together put both single-lead ECG chest straps near-perfect agreement with ECG.[1]
- The load-bearing gap is chest strap versus wrist optical — not Polar versus Garmin. Chest straps validated at MAPE 1–4%; wrist watches from both brands drifted to 4–16% against the same ECG.[1]
- The Polar H10 is the device researchers reach for as the criterion. Against a clinical ECG Holter it held 99.4% signal quality at high intensity, where the Holter dropped to 89.8%.[2]
- So buy on ecosystem, not accuracy. The H10 ($104.95) is the more universal sensor; the HRM-Pro Plus ($129.99) adds Garmin running dynamics and running power.[5][6]
For heart-rate accuracy in 2026, the Polar H10 and Garmin's HRM chest straps are effectively tied — both read the heart's electrical signal and validate near-ECG in peer-reviewed testing. The real accuracy gap is chest strap versus wrist optical, not Polar versus Garmin. Choose between the H10 and the HRM-Pro Plus on ecosystem, not on precision. Every claim below is sourced to a published validation study or a vendor page, accessed 2026-07-12.
Is Polar or Garmin more accurate for heart rate in 2026?
They tie, and there is direct evidence for it. Merrigan and colleagues (2023) ran the cleanest head-to-head available: they compared five wearables against electrocardiography during a steady-state ruck, a maximal-effort ruck, a submaximal cycle, and a Tabata circuit.[1] The Polar H10 chest strap posted a mean absolute percentage error (MAPE) of 1.28–3.40% and a concordance correlation coefficient (CCC) of 0.93–0.99; the Garmin HRM-Pro chest strap posted MAPE 1.96–3.73% and CCC 0.95–0.99. Those bands overlap — neither strap is meaningfully "more accurate." The same study is why the honest answer to the Polar-versus-Garmin question is that the brand on the strap barely matters; the sensor placement does.
What does the validation data actually show?
Here is what the published literature reports, device by device, with the criterion each study used. Two of these rows are wrist and arm sensors, included precisely because they show where accuracy is actually won or lost.
| Study | Device (worn where) | Reference | Reported accuracy |
|---|---|---|---|
| Merrigan 2023[1] | Polar H10 (chest) | ECG | MAPE 1.28–3.40%; CCC 0.93–0.99 |
| Merrigan 2023[1] | Garmin HRM-Pro (chest) | ECG | MAPE 1.96–3.73%; CCC 0.95–0.99 |
| Merrigan 2023[1] | Polar Verity Sense (armband) | ECG | MAPE 1.84–5.36%; CCC 0.98–0.99 |
| Merrigan 2023[1] | Garmin Fenix 6 (wrist) | ECG | MAPE 4.23–5.44%; CCC 0.76–0.96 |
| Merrigan 2023[1] | Polar Grit-X (wrist) | ECG | MAPE 8.49–16.45%; CCC 0.24–0.78 |
| Gilgen-Ammann 2019[2] | Polar H10 (chest) | ECG Holter | 99.4% RR signal quality at high intensity; r = 0.997 |
| Schweizer 2025[3] | Polar Verity Sense (upper arm) | Polar H10 | MAE 1.43 bpm; MAPE 1.35%; CCC 1.00 |
| Schweizer 2025[3] | Polar Vantage V2 (wrist) | Polar H10 | MAE 6.41 bpm; MAPE 6.82%; CCC 0.92 |
Read down the "worn where" column and the pattern is unmistakable: chest and upper-arm sensors cluster at MAPE 1–5%, while wrist optical spreads from tolerable (the Fenix 6) to poor (the Grit-X at up to 16.45% MAPE). Brand is not the axis. Placement is.
Why does a chest strap beat wrist optical heart rate?
It is physics, not marketing. A chest strap measures the electrical depolarisation of the heart directly (single-lead ECG), so it registers each beat as it fires. A wrist watch instead infers heart rate from light scattered by blood flow (photoplethysmography, or PPG), which is corrupted by motion artefact, sweat, cold-driven vasoconstriction, and the poorer blood perfusion at the wrist. Schweizer and Gilgen-Ammann (2025) isolated this cleanly: the same Polar optical sensor read a mean absolute error of 6.41 bpm on the wrist but only 1.43 bpm on the upper arm, against a Polar H10 reference, across nine activities from lying down to HIIT.[3] Move the optical sensor a few centimetres up the arm and most of the error disappears. During intervals, wrist HR lags the real rise and overshoots the recovery; a chest strap tracks the transition beat for beat.
Has anyone validated the HRM-Pro Plus specifically?
This is the honest caveat. The strongest head-to-head data (Merrigan 2023) tested the Garmin HRM-Pro, the direct predecessor of the HRM-Pro Plus. The Plus is a minor revision of the same single-lead ECG chest strap with the same sensing hardware, so there is every physical reason to expect identical accuracy — but no peer-reviewed study we could find isolates the HRM-Pro Plus by name.[1] Similarly, the H10-versus-Garmin comparison exists only for the HRM-Pro generation; there is no published protocol pitting the H10 against the Plus in the same session. We would rather state that plainly than round a predecessor's result into a claim about a product it did not test. For a buying decision this changes nothing: chest ECG straps validate near-ECG regardless of brand, and the H10 remains the literature's default criterion.
Polar H10 vs Garmin HRM-Pro Plus: which should you buy?
Since accuracy is a tie, decide on connectivity and metrics. The Polar H10 ($104.95) is the more universal sensor: single-lead ECG, Bluetooth LE and ANT+, two simultaneous Bluetooth connections, onboard memory for one strap-only session of up to 30 hours, and a WR30 water rating.[5] The Garmin HRM-Pro Plus ($129.99) is the better pick inside the Garmin world, adding running dynamics (vertical oscillation, ground contact time, stride length), running power, and stored treadmill pace and distance to a compatible watch, on a user-replaceable CR2032 rated up to a year at an hour a day.[6] Neither needs a subscription.
| Spec | Polar H10 | Garmin HRM-Pro Plus |
|---|---|---|
| Price (USD) | $104.95[5] | $129.99[6] |
| Sensing method | Single-lead ECG (chest)[5] | Single-lead ECG (chest)[6] |
| Connectivity | Bluetooth LE + ANT+; dual Bluetooth[5] | ANT+ and Bluetooth LE (dual)[6] |
| Extra metrics | Onboard memory, one session ~30 h[5] | Running dynamics, running power, treadmill pace/distance[6] |
| Battery | Replaceable cell, up to 400 h[5] | Replaceable CR2032, up to 1 year[6] |
| Validated accuracy | Criterion-grade vs ECG[2] | Near-ECG (HRM-Pro; CCC 0.95–0.99)[1] |
Decision frame
- Lowest price, broadest app and gym compatibility, strap-only recording: Polar H10.
- Garmin watch owner who wants running dynamics and running power: Garmin HRM-Pro Plus.
- HRV research or precise threshold work: either, with a slight edge to the H10 as the literature's default criterion.[4]
- You only care about accuracy and never sprint: a good wrist optical worn on the upper arm gets close; on the wrist during intervals, a strap removes the doubt.[3]
Accurate heart rate is only useful if the zones are set correctly. Pair either strap with the Heart Rate Zone Calculator, read Chest Strap vs Optical Heart Rate Accuracy for the physics in depth, and see Best Heart Rate Monitors 2026 for the full lineup.
Verified as of 2026-07-12. Prices vary by retailer and region; confirm on the vendor page before purchase.
Frequently asked questions
Is the Polar H10 more accurate than the Garmin HRM-Pro Plus?
Not meaningfully. Both are single-lead ECG chest straps. In the one peer-reviewed protocol that put them side by side, the Polar H10 scored MAPE 1.28–3.40% (CCC 0.93–0.99) and the Garmin HRM-Pro scored MAPE 1.96–3.73% (CCC 0.95–0.99) against ECG — a statistical tie.[1] That study tested the HRM-Pro, the direct predecessor of the HRM-Pro Plus, which uses the same sensing; no published study isolates the Plus specifically.
How much less accurate is wrist heart rate than a chest strap?
Enough to matter during hard efforts. In one validation the Polar Vantage V2 on the wrist showed a mean absolute error of 6.41 bpm (MAPE 6.82%) against a Polar H10 reference, versus 1.43 bpm (MAPE 1.35%) for the same optical sensor worn on the upper arm.[3] A separate head-to-head found wrist watches drifting to MAPE 4.23–16.45% while chest straps stayed near 1–4%.[1] The error is worst at abrupt intensity changes such as intervals.
Why do researchers use the Polar H10 as the reference device?
Because it holds its signal when a clinical Holter starts to fail. Against a medilog AR12plus ECG Holter across low- to high-intensity activity, the H10 maintained 99.4% RR-interval signal quality at high intensity — where the Holter itself dropped to 89.8% — with a correlation of r = 0.997.[2] It has also been validated for heart-rate-variability analysis against ECG.[4] That reliability is why downstream wearable studies use the H10, not a lab ECG, as their criterion.
Does the Garmin HRM-Pro Plus work with non-Garmin apps?
Yes for heart rate, partly for the extras. The HRM-Pro Plus broadcasts over both ANT+ and Bluetooth LE, so it pairs with most apps and equipment, but its running dynamics, running power, and stored treadmill pace and distance work fully only on a compatible Garmin watch.[6] The Polar H10 is the more universal sensor.[5]
Do either of these chest straps need a subscription?
No. Both the Polar H10 ($104.95) and the Garmin HRM-Pro Plus ($129.99) are one-time hardware purchases with no recurring fee.[5][6]
Did AI Fit Hub test these devices?
No. We do not run a hardware testing lab. Every accuracy figure here is drawn from a named peer-reviewed validation study and cited inline; every price and spec was read from the vendor's own page on 2026-07-12.
References
- 1 Validation of Garmin and Polar Devices for Continuous Heart Rate Monitoring During Common Training Movements in Tactical Populations (Merrigan, Stovall, Stone, Stephenson, Finomore, Hagen) — head-to-head of Polar H10, Garmin HRM-Pro, Polar Verity, Polar Grit-X and Garmin Fenix 6 vs ECG — Measurement in Physical Education and Exercise Science, 27(3):234-247 (2023)
- 2 RR interval signal quality of a heart rate monitor and an ECG Holter at rest and during exercise (Gilgen-Ammann, Schweizer, Wyss) — Polar H10 vs medilog AR12plus Holter — European Journal of Applied Physiology, 119(7):1525-1532 (2019)
- 3 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 reference — JMIR Cardio, 9:e67110 (2025)
- 4 Validity of the Polar H10 Sensor for Heart Rate Variability Analysis during Resting State and Incremental Exercise in Recreational Men and Women (Schaffarczyk, Rogers, Reer, Gronwald) — Sensors, 22(17):6536 (2022)
- 5 Polar H10 heart rate sensor — specifications and price ($104.95, ECG, BLE + ANT+, 30 h onboard memory) — Polar (2026)
- 6 Garmin HRM-Pro Plus — specifications and price ($129.99, single-lead ECG chest strap, running dynamics and power) — Garmin (2026)