Fitbit Air vs Garmin CIRQA - Direct Scientific Comparison!
In a Nutshell
Fitbit Air ($100) beats Garmin Circa ($200) in both heart rate accuracy and sleep tracking, especially during running (0.99 vs 0.89 wrist correlation) and weightlifting (0.93 vs 0.73 wrist correlation), with superior sleep stage agreement (73% vs 45% REM). Both devices reach near-perfect performance when worn on the biceps, but Fitbit maintains better overall rankings across all activities. Fitbit is the better standalone choice for health tracking, while Garmin suits users already in the Garmin ecosystem.
These notes were generated by AI and may contain inaccuracies.
The Fitbit Air costs $100 while the Garmin Circa costs $200. Testing compared both devices on the wrist and biceps across multiple exercise types including indoor cycling, outdoor running, outdoor biking, and weightlifting. A Polar H10 ECG chest strap served as the reference standard for heart rate measurements. An EEG headband (ZMAX) provided the reference standard for sleep stage measurements.
Both devices achieved a correlation of 0.99 with the reference ECG chest strap when worn on the wrist during indoor cycling. When moved to the biceps, both devices improved to a correlation of 1.00, representing perfect agreement with the reference.
The Garmin Circa on the wrist showed a correlation of 0.89 during outdoor running, with points both below and above the reference line indicating both under- and over-estimation of heart rate. The Fitbit Air on the wrist maintained a correlation of 0.99. On the biceps, the Garmin Circa improved to 0.98 correlation while the Fitbit Air achieved 0.99 correlation.
Both devices achieved a correlation of 0.92 on the wrist during outdoor biking. On the biceps, the Garmin Circa reached 0.96 correlation while the Fitbit Air achieved 0.98 correlation. The Fitbit Air showed more points close to the reference line on the biceps position.
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