Garmin vs COROS Heart Rate Accuracy

Wrist optical shows 152 bpm mid-rep. Chest strap shows 168. Your watch still paints the interval as Zone 3. Garmin and COROS wrist HR is usually fine for steady easy runs — it is not interchangeable with a strap during intervals, cold starts, or fast transitions.

Chest Strap Still Wins for Decisions

A snug, moistened ECG strap typically tracks within ~1–3 bpm of reference in steady aerobic work. Wrist LEDs infer pulse from blood volume — motion, perfusion, temperature, and fit add noise. At 170 bpm, a 5% optical error is an 8–9 beat swing — enough to mis-tag a zone. Set zones with the HR Zones Calculator.

Worked Check: Threshold Repeats

Athlete runs 5 × 5 min near threshold on a cool evening. Wrist (either brand, snug fit): averages 154 bpm with spikes to 180 on arm swing. Strap: steady 168–172 aligned with pace from the Pace Calculator. Decision: strap controls today’s workout and any LTHR test; wrist remains OK tomorrow for Zone 2 long run after warm-up. Validate easy ceilings with the Zone 2 Calculator.

When Wrist Is Enough

• Wrist OK: Zone 2, long easy runs, warm weather, steady cadence
• Use strap: intervals, tempo, threshold tests, cold starts, treadmill HR-capped sessions
• Always cross-check: RPE and pace when HR looks impossible

Related: Apple Watch vs Garmin, chest strap guide.

Brand Reality Check

Recent Garmin Elevate sensors and COROS optical both perform acceptably on steady aerobic work after a 5–10 minute warm-up with a snug fit (about two finger-widths above the wrist bone). Failure modes match: cold vasoconstriction, interval lag, cadence artifact. Pick either brand for easy volume; buy a strap for zone-critical days.

Decision Rule

If the workout’s success depends on staying in a specific HR zone (LTHR test, HR-capped easy, heat-adjusted tempo), wear a chest strap. If the run is steady Zone 2 in warm conditions and wrist matches talk test, wrist data is decision-grade — do not switch brands hunting a mythical optical winner.