Comparison between xBT and thermometer

Which is more Accurate? XBT or thermometer?

For me, it’s absolutely the thermometer - while I tend to feel shitty (autoimmune shenanigans) most days, I don’t think I could truly be at 94-95 degrees Fahrenheit (34.44 - 35 Celsius) for two days (as the xBT would indicate) without feeling extra crappy.

What about dsruptive implant, shows more Accurate than xBT and or termometer

I don’t have one myself, so I can’t attest as to what it might read in comparison.

@JennyMcLane might be able to comment on how it compares.

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Now that looks interesting :wink:
It looks somewhat similar to the graphs I made, especially with the wildly bouncing xBT curve…
Since you have an armpit install, how much difference does it make how you position your arm before reading? Like, if you keep your arm by your side for a few minutes, is the temperature notably higher?

For me, it’s definitely the thermometer. I use it to keep track of my cycle, and the data I get from the xBT would, in many cases, make absolutely no sense at all.

I made another screenshot of my graph today, data is from 01.11.2022 till today, including the initial healing time (implant was installed on 31.10.2022). Interestingly enough, the graphs look a bit more similar because of the sheer amount of data, but it is still very visible that there is no even offset or anything like that.

Oh, and you can see I was sick some days :wink:

The difference between xBT and thermometer varies from +0,08°C to -0,7°C. Definitely too much, and not caused by the healing phase - I had -0,4° and +0,05° in january…


This is a lot more variance than I experience, but it might be due to a more constant measuring time in my case… dunno. When I made some measurings during the day (I stopped doing it because it was too chaotic…), I had variance between +0,2°C to -2,6°C, so definitely more, but the placement itself might still make quite a difference.

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I haven’t noticed much of a difference to be honest - especially on the days where it was reporting that I was almost a full four degrees cooler than I was (which would warrant a hospital visit if true) I tried repeating the measurements multiple times to see if it really was measuring at that low of a temperature.

Placement definitely sounds like it might be a culprit here - hopefully we can get some more data from others with armpit and/or chest installs.

@Coma Had the biggest variance yet today…almost a full five degrees. :sweat_smile:

2023-02-14 09_20_47-Mouse Highlight Overlay

Hell… now that’s A LOT of a difference! And your data is even more inconsistent than mine… crazy.
So by now I’d say, just from the collected data of two persons (that’s really not much), the xBT is more or less worthless for accurate measuring…? That’s actually quite a surprise for me, especially since you have it installed in the recommended spot.
But it’s also a surprise because it’s not a “new” implant, so lots of people (I guess) already had one before the Flipper-hype hit - did nobody ever do any cross checks with a simple houshold thermometer? Or is there some difference in the data processing between the Flipper and the old Halo reader? I naively thought the chip would just spit out a temperature and the respective reader displays that exact temperature, but I don’t know if that’s actually the case…

Oh, and don’t get me wrong - I’m totally happy that I have the xBT and it’s still a cool thing to use it with the Flipper! I was just hoping for it to be accurate enough to use it for medical reasons, and at least currently I’m not seeing that.

That’s pretty much my conclusion too - I’m gonna try to keep on doing daily measurements through mid-May so I can at least (hopefully) feel confident about the average difference between the xBT and a “normal” thermometer in order to have a solid offset I can use - but who knows.

I haven’t seen any reports as extensive as your OP here before, although I’m sure I could potentially be missing something buried deep in the forums.

That was my assumption as well, but admittedly I am not actually sure. @amal I know you didn’t design the xBT, but do you happen to have any insight regarding variance between readers?

Oh me too for sure, I love being able to quickly boop my armpit with my Flipper and get a very very rough estimate of my temperature. If another temperature chip ever comes out that seems to be more accurate/reliable/consistent, I’ll definitely get one - and probably keep my xBT if only because removing it wouldn’t be super fun. :sweat_smile:

Ditto - I really hope I can get my hands on a good sensor heavy implant someday for this reason. I have to measure so many different things each day, it would be a huge quality of life improvement to just do that with my phone and a glassie. Hopefully we’ll have something in the next five years or so.

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I might eventually get a xBT and compare its readings with my BeUno, which gives me fairly consistent readings, but I can’t be sure they’re correct of course.

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The temperature is directly encoded in the FDXB data

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Have you done any comparisons to a regular thermometer?

Thank you!

Nope… I’m already not very disciplined to read my BeUno regularly although it’s very convenient :smile: .

A regular thermometer is a pain in the a$$ (sometimes literally) to use. And the few times I use a regular thermometer, I’m never sure I use it correctly. Under the tongue? In the armpit ? A frontal IR one ? Or in the ear ? …

Guys… doing science to arrive at answers to questions like this requires proper experiment planning… breaking down the problem into easily testable and repeatable chunks. Comparing the readings from an implanted xBT in one area of the body to any other kind of thermometer being used on another leaves too many variables to discern any meaningful conclusions.

What are the primary the questions we are asking here?

  • Is the xBT at all accurate (close to “real” temperature)?

  • What is the tolerance of the xBT sensor (how much variance from “real” temperature will it have over time?)

  • Will an xBT implanted in area X, Y, or Z of the body be able to produce clinically relevant results?

Each of these questions builds on the other, and in reality you need to build independent experiments to answer each one.

Is the xBT at all accurate (close to “real” temperature)?

  • First; find a really accurate thermometer with extremely low error margins. This is not necessarily easy… but generally speaking a good basal thermometer should do well because the application require extreme precision over a general purpose thermometer… and with the digital models you often get an extra digit of precision on the read-out. Of course that extra digit might not amount to much depending on the margin of error, but at least it’s there.

  • Now set up an experiment using warm to hot water.

    • Find a container for water that you know the diameter of and has markings for fluid amount.
    • Do a calculation using Water Cooling Calculator to find out how many minutes it will take to cool from 40C to your room’s ambient air temperature. The “desired temperature” can’t be room temp on this calculator so just set that to 1 degree above whatever the average ambient temperature of your room is.
    • Add some hot water that is around 40C to start.
    • Submerge the xBT into the water, and place the sensor end of the basal thermometer into the water.
  • Let things equalize for about a minute, and take a reading at least 3 times in a row.

This simple setup will let us know if the xBT is even remotely close to the “real” temperature, assuming the basal thermometer is properly calibrated etc. Also by immediately taking 3 to 5 readings, we will also get to see if the margin of error is drastic or subtle.

  • Depending on the cooling calculator’s output, you will want to take 2 back to back readings at an interval that will get you at least 10 readings spaced out by at least 1 minute between before the water reaches ambient temperature. So, the larger the container, the slower the water will cool. If the calculator tells you it will only take around 6 minutes to go from 40C to “room temp” whatever that is, then you’ll probably want a bigger container.

  • Of course, taking the readings should require minimal interference with the water in the container. You should try to set things up so you can take a reading from the xBT without having to reach in and grab it. The basal thermometer should be able to be activated without having to remove it from the water as well.

Will an xBT implanted in area X, Y, or Z of the body be able to produce clinically relevant results?

Now that we have some understanding of the xBT’s accuracy and margin of error across the relevant thermostatic range, we can move on to the next test - testing the efficacy of different subdermal locations on the body.

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Ooookay… I’m currently on holiday, and I’ve got an xBT lying around here, so maybe I’m gonna try this out (though the chip is all nice and sterile still, and I hesitate on changing that). But I assumed that Destron Fearing built a chip that fulfills at least this

requirement. I mean, it is used for medical reasons - albeit on animals, but considering how expensive especially horses can be, I know there is little margin for errors in that field.
For similar reasons I trust my basal thermometer - women use it to prevent pregnancy, and that’s quite a serious task, so the tools have to work well.

And while I totally agree that there are lots of variables considering chip placement, thermometer used, amount of clothing, surrounding temperature and tons of other things, it’s finally the everyday use that is important. Let’s say the experiment you suggest shows that the sensor itself is fine and is spitting out the same temperature as the thermometer (or something else with a solid offset) - and that’s honestly what I think would happen, I don’t think the sensor is “broken” or unreliable - it is still an existing problem, seemingly, that there is no consistent offset in everyday implantee use.

Main problem is, we have too little data - while @biospoonie and me have relatively similar results, it’s only two people. With 100 people (still a small group) or maybe even 10 one could at least see some pattern - far from scientifically viable, I know, but if we experience wildly variying offsets in everyone, there seems to be something going on :wink:


I still need to get mine installed, bern procrastinating

I think In my usual manner I’ll over complicate things, but have a blast at it

Im going to try to add 2 or 3 other data points into the mix to see if it shows anything

I’ll plan to measure
XBT temperature
Oral temperature
(Maybe forehead skin temperature)
And also try to log ambient room temperature
And make a note of what type of clothes I’m wearing


This is definitely a good thing to do! Since I take my temperature before getting up, I always take care that the bedsheet was covering my body before.
When I took temperature during the day, it definitely made a difference how much I was wearing.

Woohoo - that makes at least three of us who do regular measuring! So I’d say we just have to convince some more people here… like…



I guess I could also just get a basal thermometer and do the test… it would make for good YouTube content maybe


I have a dsruptive temperature chip and a xBt. If you look at the technical specification of the xBt it shows at tests with horses that there is a 3 ° Celsius difference between the xBt and the actual body temperature. If you compare the results with the xBt and the desruptive chip, it verifies this 3 ° celcius difference.