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Rated 1 out of 5 stars

Received a faulty sensor as a Christmas present that was unable to pair with my phone. I've been unable to contact core for a replacement and my product is now listed as sold out

Rated 1 out of 5 stars

Was really looking forward to trying product. Unfortunately after purchasing a few month ago the item still has arrived and Core are being unresponsive to my emails. Gutted. Please no one buy there pr... See more

Rated 2 out of 5 stars

Unreliability connects to the app. Data is lost or disappears at times. Sometimes doesn't connect to the watch. I've given two stars as when working I find some use for this. But disappointed with... See more

Rated 5 out of 5 stars

I have been using the Core Sensor for several months and the App has been improved significantly during this period. I find the graphs useful and like way the results are presented. The battery lasts... See more

Company details

  1. Electronics Manufacturer
  2. Outdoor Sports Store

Written by the company

The CORE Body Temperature Sensor is an easy-to-use, wearable device that uses Swiss-Made sensor technology and can monitor and deliver real-time, accurate core body temperature data. CORE's team includes a seasoned group of professional in the fields of engineering, data science, sports, business and marketing, working together to bring our innovative energy transfer sensing solutions into the field of sports and beyond. CORE is a venture of greenTEG AG, a Swiss engineering company based in Zurich (Switzerland).


Contact info

2.4

Poor

TrustScore 2.5 out of 5

28 reviews

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Hasn’t replied to negative reviews

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Rated 1 out of 5 stars

Poor Refund Process and Lack of Communication

I returned my CORE device almost a month ago, and the refund has still not been processed. There was no notification from the company confirming they received my return, even though tracking shows it was delivered.

It took two emails just to get a return label, which took a week to arrive—and I had to pay for the return shipping myself. Overall, the lack of communication and the slow, inconvenient return process have been very frustrating.

August 9, 2025
Unprompted review
Rated 1 out of 5 stars

Was really looking forward to trying…

Was really looking forward to trying product. Unfortunately after purchasing a few month ago the item still has arrived and Core are being unresponsive to my emails. Gutted. Please no one buy there product mine didn’t even come, no replacement sent or refund provided

June 27, 2025
Unprompted review
Rated 2 out of 5 stars

Core Body Temp - Is It Needed?

Purchased the first version sensor for £230+VAT last year, was offered the option to upgrade to version two in for £154.67+VAT which I did March 27th.

New device still not arrived but showing as ready to be shipped May 2nd.

In all honestly, I achieve the 10/10 rating every session by wrapping up warm and executing 110 minutes on the trainer with a fairly hard start for 10 minutes. So the device is only re-confirming what I've "calibrated" in my environment. 7/10 takes around 24 minutes less (each +1 takes around 8 minutes). I like having the data point - but I'm sure I could achieve the same benefits without it indoors. Outdoors in a hot climate - it would be more beneficial.

May 15, 2025
Unprompted review
Rated 2 out of 5 stars

Unreliable

Unreliability connects to the app. Data is lost or disappears at times. Sometimes doesn't connect to the watch. I've given two stars as when working I find some use for this.
But disappointed with overall purchase due to its unreliability. Went back and forward with their support who haven't really resolved at all despite being within its warranty period. I would recommend avoiding.

May 6, 2025
Unprompted review
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Rated 5 out of 5 stars

I have been using the Core Sensor for…

I have been using the Core Sensor for several months and the App has been improved significantly during this period. I find the graphs useful and like way the results are presented. The battery lasts several days and recharges in about three hours. Set up is quick and easy with the clips holding the sensor in place nicely. The results are great and customer service have been good at dealing with any issues. The only bad thing is the sensor is not compatible with Frontier X2.

November 12, 2022
Rated 2 out of 5 stars

Good but would not buy it again

Sensor works well and seems very sensitive. It could easily recognise when I had Covid. But it is expensive and the updated App is basically not more clear/explicit than the previous version. Especially it's seems not possible to see you trend more than 24h which is a shame. Also the tutorials on how to use it and extract the maximum out of it is not very detailed.

July 12, 2022
CORE sensor logo

Reply from CORE sensor

Hi, Tino

Thanks for your review. The new app has a Diary feature that allows users to track every day of the year with just one click. Also, you can upload the data to the cloud, if you need a more detailed tracking. Please, let us know if you have issues with these features, we will kindly help you to get the best out of your CORE. Also, if you need something else, you can do a feature request and we will take that into consideration.
Regarding the tutorials, please don't hesitate to reach back for support. We are always improving these guides, and your feedback and experience will surely be of great help for that purpose. Have a nice day.

With kind regards,

The CORE team

Rated 1 out of 5 stars

Clinical = good, athletes = not so good.

To better elaborate here on "not being validated" - I'll restate that and state, it's not validated in athletic populations but has efficacy in clinical situations.

The current literature surrounding (which is minimal) the device does not fully support (sadly) the claims made on CORE's website, where depending on the intensity of the exercise, the device becomes increasingly unreliable. As it stands, I would advise athletes and coaches be aware if they do use the device - and like most things, more research is needed (independent studies, that is).

Reference: Verdel and colleagues 2021 "Reliability and Validity of the CORE Sensor to Assess Core Body Temperature during Cycling Exercise"

July 5, 2022
CORE sensor logo

Reply from CORE sensor

We notice that this comment has again been edited and acknowledge that disapproval has been published across multiple channels and sites.

We remained helpful and proactive in supporting your testing - our direct dialogue during this time confirms this.

For sports use, the high level of adoption, and continued use over years by the worlds leading athletes, performance coaches and teams suggests the suitability of the CORE sensor in training and racing for performance sports.

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Rated 5 out of 5 stars

Wished I purchased sooner!

As advertised. The CORE device has opened my understanding to temperature based performance based metrics. I only wish I had bought it sooner!

May 25, 2022
Rated 5 out of 5 stars

Excellent custom support

Excellent custom support.
I had a problem with the device, and as soon as I got in contact with CORE they offer me the best solution.
Thanks very much

May 25, 2022
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Rated 5 out of 5 stars

Excellent shop and support services, great devices

I reviewed CORE device separately (5*, definitely recommended for serious outdoor activity all year around). As for corebodytemp.com and provided services (sale, support, cloud app), my experience is great. No issues with on-line purchase and the one support issue I had (Coros app not showing temperature graph - was bug in Coros), the response was really engaged and helpful.

May 25, 2022

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