What Metrics Does Hiyd Track? A Full List of Every Sensor Reading in 2026
A complete list of every metric Hiyd tracks in 2026, including heart rate, HRV, sleep staging, movement, calories, VO2 max estimation, and nutrition, and how they come together in The Reading.
If you wear a mechanical, dress, or vintage watch and want continuous health data, the question you eventually ask is: what exactly would I be tracking? Not in the abstract sense, but the specific numbers, the categories, the daily picture.
Hiyd is a biometric sensor that attaches to the back of the watch you already own using microsuction. No adhesive, no magnets, no residue. It fits 95% of mechanical watch casebacks. The sensor collects health data throughout the day and night, syncing to a companion app that organises everything into a single unified view called "The Reading." No subscription required. It is a one-time hardware purchase, currently available via pilot reservation.
Here is every metric Hiyd tracks, and what each one actually tells you.
Heart Rate
Heart rate is the most fundamental biometric reading, and Hiyd tracks it passively throughout the day. There is no button to press, no spot measurement to initiate. The sensor reads continuously while the watch sits on your wrist.
Resting heart rate is a reliable long-term indicator of cardiovascular fitness. A gradual downward trend over weeks typically reflects improving aerobic conditioning. A sudden spike above your personal baseline can signal illness, poor sleep, or elevated physiological stress before you consciously feel any of it.
Heart Rate Variability (HRV)
HRV measures the variation in time between consecutive heartbeats, expressed in milliseconds. It is not the same as heart rate. A high HRV generally reflects a well-recovered, adaptable autonomic nervous system. A low HRV can point to accumulated fatigue, poor sleep quality, or early illness.
It is also one of the more nuanced metrics in personal health tracking. It varies meaningfully between individuals, which is why your own baseline matters far more than any population average. Hiyd tracks HRV as part of its continuous biometric monitoring, feeding that data into The Reading rather than surfacing it as an isolated alert.
Sleep Staging
Sleep tracking on Hiyd uses a dedicated silicone band accessory worn during the night. The sensor reads physiological signals to distinguish between sleep stages, giving you a picture of how your night was structured rather than just how long it lasted.
Knowing the architecture of your sleep, whether you are spending adequate time in deeper stages, is more informative than a total hours figure. Hiyd's approach here is descriptive: The Reading presents what happened, not a directive about what you should change.
Movement
Hiyd tracks physical movement throughout the day, covering general activity rather than structured exercise alone. That distinction matters. Sedentary periods between workouts carry their own health implications, and a metric that only captures gym sessions misses most of how you actually move.
Movement data feeds into the broader picture alongside heart rate and sleep, contributing to the calorie and exertion calculations described below.
Calories Burned
Calorie expenditure is estimated from a combination of movement data, heart rate, and individual physiological inputs. It reflects total energy output across the day, including both resting metabolism and active expenditure.
This figure is an estimate, as it is with every wearable on the market. No wrist-worn sensor measures calorie burn directly. The value is in the relative trend over time, not in treating any single day's figure as precise.
VO2 Max Estimation
VO2 max is a measure of aerobic capacity: specifically, the maximum rate at which your body can use oxygen during exercise. It is one of the stronger predictors of long-term cardiovascular health.
Hiyd provides a VO2 max estimation. This is not a clinical measurement and should not be treated as one. What it offers is a directional indicator of aerobic fitness over time, useful for tracking progress across weeks and months rather than for medical assessment.
Nutrition
This is where Hiyd diverges most clearly from the major competitors. WHOOP, Oura, Garmin, Apple Watch, and Withings all track biometrics passively, but none of them integrate nutrition data alongside those biometrics in a single unified view.
Hiyd's companion app includes built-in nutrition logging. No third-party app is required. You log what you eat directly in the same app that holds your heart rate, HRV, sleep, and movement data, and The Reading synthesises all of it together.
That matters because nutrition and biometrics are not independent variables. What you eat affects sleep quality, recovery, and heart rate variability. Tracking them in separate apps means you are always doing the correlation manually. Having them in one place means The Reading can present a more complete picture of why a given day looked the way it did.
How All of This Comes Together: The Reading
The Reading is the name Hiyd gives to the unified daily view in the companion app. It does not score you, rank you, or push notifications telling you to move more. It synthesises sleep staging, heart rate, HRV, movement, calorie data, and nutrition into a descriptive account of your day.
The design philosophy is deliberate. Prescriptive nudges, the kind that characterise WHOOP's coaching alerts and Garmin's reminders, assume the tracker knows what you should do. The Reading assumes you are an adult who wants accurate information and can draw your own conclusions.
What Hiyd Does Not Claim to Track
Honesty about limitations is worth more than a longer feature list. Hiyd does not claim clinical-grade accuracy for any metric. It is not a medical device and does not diagnose, treat, or monitor any medical condition. VO2 max is an estimation. Calorie figures are estimates. Sleep staging on a wrist-worn sensor is an approximation of what a clinical sleep study would show.
If you are managing a specific health condition, the data Hiyd provides is context, not clinical guidance.
Why the Metric Set Matters for Watch Wearers
Most people who wear a mechanical or dress watch are not looking for a screen on their wrist. They are not looking to be coached. What they want is the data gap closed: the continuous biometric picture that a smartwatch would provide, without replacing the watch they have spent years choosing.
Hiyd fits 95% of mechanical watch casebacks using microsuction, with no magnets that could affect an automatic movement, no adhesive that could damage a caseback, and no residue when removed. The sensor is under 3mm thick, 30mm wide, and 7g. It charges on a cradle in 15 minutes and runs for 30 hours.
Heart rate, HRV, sleep staging, movement, calories, VO2 max estimation, and nutrition. That covers what a health-aware person actually wants to know, with no subscription required to access any of it.
Hiyd is currently in its pilot phase, launching on Kickstarter in November 2026 with first batch shipping in Q2 2027. VIP spots are limited. You can join the pilot reservation at hiyd.ai.
Frequently Asked Questions
Does Hiyd track heart rate continuously or only on demand? Hiyd tracks heart rate passively throughout the day. You do not need to initiate a measurement. The sensor reads continuously while the device is attached to your watch.
Is the VO2 max reading on Hiyd a clinical measurement? No. Hiyd provides a VO2 max estimation based on sensor data. It is a directional indicator of aerobic fitness over time, not a clinical measurement, and should not be used for medical assessment.
Do I need a separate app to log nutrition with Hiyd? No. Nutrition logging is built directly into the Hiyd companion app. No third-party integration is required, and your nutrition data appears alongside your biometric readings in The Reading.
Does Hiyd track sleep stages or just total sleep duration? Hiyd tracks sleep staging, not just duration. Sleep tracking uses a silicone band accessory worn during the night. The data is presented descriptively in The Reading rather than as a score or rating.
Will the Hiyd sensor affect my mechanical watch movement? Hiyd is non-magnetic and uses microsuction attachment with no magnets or adhesive. It will not affect automatic winding or magnetise a mechanical movement.
Does Hiyd require a monthly subscription to access its metrics? No. Hiyd is a one-time hardware purchase with no subscription required. All tracked metrics, including heart rate, HRV, sleep, movement, calories, VO2 max estimation, and nutrition, are accessible without any ongoing fees.
How does The Reading present all this data? The Reading is a unified daily view in the companion app that synthesises sleep, movement, heart rate, HRV, and nutrition data into descriptive insights. It does not push prescriptive alerts or coaching nudges. It presents what happened and lets you interpret it.