Garmin CIRQA Smart Band: The Thin Sensor Explanation Does Not Add Up
Garmin has explained why the CIRQA Smart Band uses the older Elevate Gen 4 sensor rather than the Gen 5 in its current watches. Product manager Chrissy Wheeler told Forbes it came down to size: “The reason we didn’t go for the very latest one is the size of the module.” The Gen 5, she said, would have made the band thicker.
Hmm. Really? I don’t think so. Here’s why.
Fact: Garmin already sells a thinner device with the newer sensor inside it. The Index Sleep Monitor uses Elevate Gen 5 (with ECG disabled) and is 7.8mm thick. The CIRQA uses Elevate Gen 4/4.1 and is 9mm thick.
A wider pod lets components lie flat, which is part of how the 37.6mm Index Sleep Monitor reaches 7.8mm. The narrow CIRQA has to stack them. That is the shape Garmin chose, not a limit the sensor imposed.
Gen 5 is the physically larger sensor, because it adds emitters that help when a heavier watch moves around during hard efforts. A light band moves less and needs them less. That is a fair reason to prefer Gen 4 here, but it is not the reason Garmin gave, and it is a point about width rather than thickness. Either way, the Index Sleep Monitor carries Gen 5 in a thinner body, so neither framing holds.
The likelier reasons are the two Garmin did not give: Elevate Gen 4 is cheaper, and it draws less power, which matters on a band selling at $199.99 delivering a ten-day battery.
Full specifications are at the Garmin CIRQA specs page. Whether the older sensor actually costs CIRQA accuracy is tested directly in the full review: excellent in the gym, yoga and cycling, with failures specific to open water swimming and running intervals.
Garmin CIRQA Smart Band
Screenless health and fitness band (no subscription required)
+other retailersQuick answers
Why does the Garmin CIRQA use the older Elevate Gen 4 sensor?
Garmin says the Gen 5 sensor would have made the module thicker. That explanation is hard to square with Garmin’s own Index Sleep Monitor, which carries Gen 5 at 7.8mm against the CIRQA’s 9mm. The likelier reasons are cost and battery draw, since Gen 4 is cheaper and draws less power, which suits a $199.99 band with a ten-day battery.
Is the Garmin CIRQA less accurate because of the Gen 4 sensor?
Not necessarily. Fit, placement and movement affect optical readings as much as sensor generation, and the CIRQA’s Gen 4 has been modified to add skin temperature. Published Gen 4 versus Gen 5 comparisons predate this variant, so it needs its own testing.
How thick is the Garmin CIRQA compared to the Index Sleep Monitor?
The CIRQA module is 9mm thick. The Index Sleep Monitor is 7.8mm thick and uses the newer Elevate Gen 5 sensor. The Index Sleep Monitor pod is also wider, which allows a thinner build for the same internals.
Last Updated on 19 August 2026 by the5krunner
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tfk is the founder and author of the5krunner, an independent endurance sports technology publication. With 20 years of hands-on testing of GPS watches and wearables, and competing in triathlons at an international age-group level, tfk provides in-depth expert analysis of fitness technology for serious athletes and endurance sport competitors. ID
Venu X1 (7.9 mm thin) is also thinner than Cirqa but uses Elevate 5. This is really strange.
tell that to the Garmin product manager!
(well spotted, i missed that one)
But the X1 doesn’t get 10 days of battery life…..
A thicker band could also refer to width of the band on your arm. Notice people complaining the band is wider then the fitbit air? They may not have wanted it any wider