Knowledge
Magazine
-
Oura vs Whoop vs Apple Watch: The Quantified Scientist on What the Accuracy Data Shows
15 min read
-
The Complete Guide to Testosterone Optimization — Part 3: Stress, Psychology, and Purpose
9 min read
-
Dr. David Barzilai: A Harvard Medical School Lecturer on the Five Health Habits Worth Your Time
18 min read
Weekly picks on longevity, brands, and health science. No spam—unsubscribe anytime.
Tools
- →The 30s Longevity Guide for Women
- →Postpartum Recovery Guide
- →Perimenopause Longevity Guide
- →Dopamine Reset Guide
- →Pregnancy Longevity Guide
- →Peptide Guide
- →Home Detox Guide
- →Slow Aging Guide
- →Pro Supplement Guide
- →Safe Supplement Guide
- →Bio Age Calculator
- →Blood Testing Guide
- →Deep Sleep Guide
- →Pro Longevity Dashboard
By Category
By Goal
Knowledge
- →What is Longevity?
- →Improve diet
- →More focus
- →Look younger
- →Lose weight
- →Track biomarkers
- →Improve sleep
- →Build muscle
- →Increase cardio
- →Detect diseases
- →Recover faster
- →Relieve stress
Magazine
-
Oura vs Whoop vs Apple Watch: The Quantified Scientist on What the Accuracy Data Shows
15 min read
-
The Complete Guide to Testosterone Optimization — Part 3: Stress, Psychology, and Purpose
9 min read
-
Dr. David Barzilai: A Harvard Medical School Lecturer on the Five Health Habits Worth Your Time
18 min read
Weekly picks on longevity, brands, and health science. No spam—unsubscribe anytime.
Brands
- →Apps
- →At Home Tests & Kits
- →Events
- →Experts & Clinics
- →Foods & Beverages
- →Gadgets & Equipment
- →Gyms & Workouts
- →Supplements
- →Travel & Retreats
- →Wearables & Trackers
Tools
- →The 30s Longevity Guide for Women
- →Postpartum Recovery Guide
- →Perimenopause Longevity Guide
- →Dopamine Reset Guide
- →Pregnancy Longevity Guide
- →Peptide Guide
- →Home Detox Guide
- →Slow Aging Guide
- →Pro Supplement Guide
- →Safe Supplement Guide
- →Bio Age Calculator
- →Blood Testing Guide
- →Deep Sleep Guide
- →Pro Longevity Dashboard
Discover
Connect
Community Discussions
My experiences with the Calibre Biometric Tracker (regular VO2Max and FatMax testing)
I ordered the Calibre Biometric Tracker (US) from Germany and will receive it today (shipment duration approx 10-12 days with default Fedex shipment option). My goal is to analyze VO2Max and FatMax in the context of cycling on a regular basis. If any of you are interested in the device, feel free to ask questions or comment on your experiences here.
By the way, ordering directly from Calibre Biometric (US) was easy, but keep in mind that you will have to pay additional import duties and processing fees. For me, that was 102.29 EUR. But still a fair investment compared to VO2Master or similar devices. I am looking forward to my first test sessions.
Update 2026-05-13 - for Calibre Bio users: If anyone here is running into trouble with the official app — or just wants a backup plan in case it stops working — you can try openspiro.com. It's a free desktop app (Mac/Windows/Linux) that talks to the Calibre device directly over Bluetooth and stores your sessions locally on your own computer. Works fully offline, no login, no cloud. I built it because I own a Calibre myself and wanted to keep using mine regardless of what happens to the company.
I ordered the Calibre Biometric Tracker (US) from Germany and will receive it today (shipment duration approx 10-12 days with default Fedex shipment option). My goal is to analyze VO2Max and FatMax in the context of cycling on a regular basis. If any of you are interested in the device, feel free to ask questions or comment on your experiences here.
By the way, ordering directly from Calibre Biometric (US) was easy, but keep in mind that you will have to pay additional import duties and processing fees. For me, that was 102.29 EUR. But still a fair investment compared to VO2Master or similar devices. I am looking forward to my first test sessions.
Update 2026-05-13 - for Calibre Bio users: If anyone here is running into trouble with the official app — or just wants a backup plan in case it stops working — you can try openspiro.com. It's a free desktop app (Mac/Windows/Linux) that talks to the Calibre device directly over Bluetooth and stores your sessions locally on your own computer. Works fully offline, no login, no cloud. I built it because I own a Calibre myself and wanted to keep using mine regardless of what happens to the company.
Please sign in to post a reply.
€443,95 EUR + 100 EUR + in fees sounds a lot but FatMax and RMR (Resting Metabolic Rate Protocol) are special and maybe worth the money... I´d love to have a good VO2Max Tracker that i can wear all the time... What do you all think about the Apple Watch VO2Max Tracking quality?
€443,95 EUR + 100 EUR + in fees sounds a lot but FatMax and RMR (Resting Metabolic Rate Protocol) are special and maybe worth the money... I´d love to have a good VO2Max Tracker that i can wear all the time... What do you all think about the Apple Watch VO2Max Tracking quality?
@andy O2Max numbers from smartwatches are only "calculated" base on heart rate (and performance metrics, e.g. power measurement on the roadbike). If you want real numbers you must use a device based on respiratory gas analysis.
@andy O2Max numbers from smartwatches are only "calculated" base on heart rate (and performance metrics, e.g. power measurement on the roadbike). If you want real numbers you must use a device based on respiratory gas analysis.
Curious to hear how satisfied you are with it! It would be great to compare it against a proper spiroergometry test at some point to gauge its accuracy.
I did one on an ergometer at years.co two weeks ago, but to be honest, it wasn’t the best experience given my current training routine. I usually lift heavy weights twice a week and do 2x Zone 2 and 1x VO2max interval run per week, so using a bike felt quite off. My legs got sore quickly since the stimulus was very different from my usual training, mostly targeting my lower body.
In Germany, a lab-based spiroergometry usually costs around €199–259. So if the device turns out to be within 3–5% accuracy of that, it would still be a really solid value.
Curious to hear how satisfied you are with it! It would be great to compare it against a proper spiroergometry test at some point to gauge its accuracy.
I did one on an ergometer at years.co two weeks ago, but to be honest, it wasn’t the best experience given my current training routine. I usually lift heavy weights twice a week and do 2x Zone 2 and 1x VO2max interval run per week, so using a bike felt quite off. My legs got sore quickly since the stimulus was very different from my usual training, mostly targeting my lower body.
In Germany, a lab-based spiroergometry usually costs around €199–259. So if the device turns out to be within 3–5% accuracy of that, it would still be a really solid value.
UPDATE: What I discovered in my testing with the Calibre Bio:
The device must be charged at least 30min before you can use it. This warms up the oxygen sensor. Without that the device doesn't get ready to measure correctly.
The calibre bio device is really sensitive to external air sources. You can't even use a fan when doing VO2max tests on your indoor bike and it won't work outdoors.
The power button feals too cheap/plastic. It's really hard to find out if you put off the device correctly.
But besides that downsides: the measuring just works and I really like the possibility to check my VO2Max and FatMax based on the live measuring in the calibre bio app. Really cool!
UPDATE: What I discovered in my testing with the Calibre Bio:
The device must be charged at least 30min before you can use it. This warms up the oxygen sensor. Without that the device doesn't get ready to measure correctly.
The calibre bio device is really sensitive to external air sources. You can't even use a fan when doing VO2max tests on your indoor bike and it won't work outdoors.
The power button feals too cheap/plastic. It's really hard to find out if you put off the device correctly.
But besides that downsides: the measuring just works and I really like the possibility to check my VO2Max and FatMax based on the live measuring in the calibre bio app. Really cool!
Updated my Calibre Bio to the new 2.0 firmware. Upgrade was easy and fast. Don't know if it has something todo with the firmware but my battery issues are gone (device did not show more than 30% battery even when charged for ours).
Updated my Calibre Bio to the new 2.0 firmware. Upgrade was easy and fast. Don't know if it has something todo with the firmware but my battery issues are gone (device did not show more than 30% battery even when charged for ours).
Ahh. This is cool! You can export your calibre bio sessions as csv and let ChatGPT build graphs (e.g. my short indoor bike session test this morning). I'll try to combine my Garmin Edge data with the data from the Calibre bio based on the heartrate next. Stay tuned.
Ahh. This is cool! You can export your calibre bio sessions as csv and let ChatGPT build graphs (e.g. my short indoor bike session test this morning). I'll try to combine my Garmin Edge data with the data from the Calibre bio based on the heartrate next. Stay tuned.
UPDATE after some weeks of testing: Calibre Bio is really great when you get used to it. I use it regularly now to measure my FatMax and VO2Max (separate things and testing sessions). Here's my fatmax testing workflow:
- Eat normal the day before. Stop eating 14 hours before the test in the next morning.
- Start charging your Calibre Bio device (non accelerated USB-C charger)
- Calibre Bio with Polar H10 attached (heart rate is important to get the sync with garmin performance data later)
- Garmin Edge, Garmin vector watt measure pedals, Garmin Forerunner 965 (for heartrate in the garmin session)
- 14h hours after stop eating - e.g. at 08:00 in the next morning: Push Calibre Bio button for 10 seconds to initiate the calibration/warmup
- At least 30min later: Start your FatMax protocol from the Calibre Bio website
- Export your Calibre Bio Session as csv
- Export your Garmin Session as tcx
- Let Chatgpt sync and analyze the files by using the heartrate as sync values.
See the screenshot attached for details (didn't follow the protocoll exactly but just did a slow ride on my indoor bike to find out my fatmax)
UPDATE after some weeks of testing: Calibre Bio is really great when you get used to it. I use it regularly now to measure my FatMax and VO2Max (separate things and testing sessions). Here's my fatmax testing workflow:
- Eat normal the day before. Stop eating 14 hours before the test in the next morning.
- Start charging your Calibre Bio device (non accelerated USB-C charger)
- Calibre Bio with Polar H10 attached (heart rate is important to get the sync with garmin performance data later)
- Garmin Edge, Garmin vector watt measure pedals, Garmin Forerunner 965 (for heartrate in the garmin session)
- 14h hours after stop eating - e.g. at 08:00 in the next morning: Push Calibre Bio button for 10 seconds to initiate the calibration/warmup
- At least 30min later: Start your FatMax protocol from the Calibre Bio website
- Export your Calibre Bio Session as csv
- Export your Garmin Session as tcx
- Let Chatgpt sync and analyze the files by using the heartrate as sync values.
See the screenshot attached for details (didn't follow the protocoll exactly but just did a slow ride on my indoor bike to find out my fatmax)
Hey @brgmn thanks a lot for your in detail report! I bought the Lactolevel last year and made a video about it: https://www.youtube.com/watch?v=CBwu-EAKsno&t=6s
Unfortunately the company doesn't exist anymore. It looks like Calibre had a better market fit. Based on what you write it feels quite similar to the Lactolevel. It's not easy to use. Only after some sessions you are familiar with the device.
I compared my Whoop, Garmin and the Lactolevel VO2Max. All three were similar (+-2).
Hey @brgmn thanks a lot for your in detail report! I bought the Lactolevel last year and made a video about it: https://www.youtube.com/watch?v=CBwu-EAKsno&t=6s
Unfortunately the company doesn't exist anymore. It looks like Calibre had a better market fit. Based on what you write it feels quite similar to the Lactolevel. It's not easy to use. Only after some sessions you are familiar with the device.
I compared my Whoop, Garmin and the Lactolevel VO2Max. All three were similar (+-2).
UPDATE: The company behind Calibre Bio filed for bankruptcy https://newzapiens.com/community/general/calibre-bio-bankruptcy-what-it-means-and-why-garmin-should-pay-attention
UPDATE: The company behind Calibre Bio filed for bankruptcy https://newzapiens.com/community/general/calibre-bio-bankruptcy-what-it-means-and-why-garmin-should-pay-attention
It is probably not so interesting now but I had a look inside the Calibre Bio: https://youtu.be/q2cS--6lyiI?si=9jQBPTn11sB63_Zu
It is probably not so interesting now but I had a look inside the Calibre Bio: https://youtu.be/q2cS--6lyiI?si=9jQBPTn11sB63_Zu
Hi Martin: Was reading your review here and I saw you noted that Calibre are using servers to store their data. This surprises me as the App still works for me here in Canada and appears to process everything on device. I'm assuming you were able to confirm that's not the case?
Hi Martin: Was reading your review here and I saw you noted that Calibre are using servers to store their data. This surprises me as the App still works for me here in Canada and appears to process everything on device. I'm assuming you were able to confirm that's not the case?
