Circular Ring 2 tracks your skin temperature continuously, day and night, measuring changes against your personal baseline. The signal that matters is the variation over time. Continuous skin temperature tracking, paired with an AI health coach, turns those trends into one clear action you can take every day.
Order Circular Ring 2A thermometer captures one moment. Most wearables sample temperature only during sleep, and many wrist-based monitors miss the signal entirely because daytime skin temperature shifts too much with the environment to be useful. The temperature pattern that matters lives in your overnight trend, compared against your own baseline, day after day.
A thermometer tells you your temperature in one moment. The pattern across days is where the useful information lives.
Some wearables measure temperature only briefly during sleep. The full variation across the night, and across the day, is what reveals real patterns.
Temperature is deeply personal. Comparing your reading to a generic "normal" tells you almost nothing about your own body.
Circular Ring 2 tracks your skin temperature day and night, then compares each night's average to your personal baseline. It flags meaningful changes in your temperature trend and then connects those changes to your sleep, recovery, and cycle, giving you one clear thing to do today.
The ring captures your skin temperature day and night, not in periodic samples. The analysis anchors to your overnight average, since daytime readings are too affected by other factors.
Your readings are compared against your own normal, not a population chart. A deviation invisible on a generic chart can be meaningful against your own data.
Your overnight average is the signal that matters. During sleep, your environment stays stable enough for the algorithms to isolate what your body is actually doing.
Your temperature is read alongside your sleep stages, recovery, energy score, and cycle phase. The pattern becomes useful because it sits inside the wider picture.
When your temperature variation suggests something is off, Kira AI translates it into one action: rest, monitor symptoms, adjust your sleep, or check your cycle phase.
In very cold conditions, reduced blood flow to the fingers can affect signal quality. Unusual readings on cold nights are most likely explained by this.
For three nights, your overnight temperature runs a quarter degree above baseline. You feel fine. The trend is a cue to ease off, sleep a little more, and pay attention to how you feel.
Your temperature drops through your period, climbs after ovulation, and stays elevated through your luteal phase. You can finally see the shape of your cycle, not just feel it.
You've tracked your cycle manually for months. The post-ovulation rise was always the signal, but catching it meant waking at the same time every morning before moving. Circular Ring 2 captures it overnight, automatically, so the window shows up on its own.
You land after a long flight. Your overnight temperature runs high for three nights, alongside fragmented sleep and dropped HRV. Kira AI gives you a recovery rhythm. By night four, you're back to baseline.
Two glasses of wine with dinner. Your overnight temperature runs slightly higher than the night before. Alcohol disrupts thermoregulation during sleep, and the ring picked it up.
A heavy work month. Your overnight temperature has been quietly elevated for weeks, alongside dropped HRV and rising stress. The trend was the early signal you missed.
You were unwell last week. You feel better, but your overnight temperature has not fully settled back to your baseline yet. The ring shows that return, so you don't push too soon.
A 0.8°C / 1.4°F rise in overnight temperature means very little on its own. The same rise after a long flight, a stressful week, or a cycle phase change means three different things, each calling for a different response.
Kira AI reads your temperature alongside every signal Circular Ring 2 captures, including your sleep, HRV, recovery, stress, and cycle. It finds the pattern, identifies the likely cause, and writes one specific recommendation in plain language. Rest tonight. Push your workout. Monitor your symptoms. Anchor your bedtime. The answer is shaped to your body and your day.
Circular Ring 2 measures skin temperature continuously through a digital temperature sensor inside the ring. The finger is one of the most reliable places on the body for stable optical and thermal readings, with strong arterial flow and consistent contact across the day and night.
The ring captures temperature 24/7. Daytime readings are recorded, but the variation analysis is anchored to the overnight average, because daytime skin temperature is heavily influenced by environment, activity, and clothing.
Skin temperature varies throughout the day with circadian rhythm, activity, environment, and chronotype, so a single absolute reading can be misleading. The variation against your own baseline is the signal that matters.
Each night's average is compared against your personal 14-day baseline. Deviations larger than approximately 0.8°C / 1.4°F are typically meaningful and worth attention. Smaller variations are normal and reflect daily life.
A rise that lasts several nights is worth paying attention to, alongside how you feel. Cycle phase changes typically follow a predictable monthly pattern. Recovery strain from travel, alcohol, or a stressful stretch can elevate temperature for several days. Environmental shifts like a hot bedroom or a season change also appear in the data.
Circular Ring 2 is not a medical device. It does not detect fever, diagnose illness, predict disease, or confirm ovulation medically. The temperature variation feature is a wellness tool that supports awareness of body changes. If you suspect a fever, use a clinical thermometer. For any medical concern, consult a doctor.
Loose ring fit, cold fingers, low circulation, a very hot or cold bedroom, sauna use, intense pre-bed exercise, alcohol, and late meals can all influence your overnight temperature reading. The system filters where possible, but a single unusual night is not always meaningful.
Temperature data is encrypted and processed with GDPR and HIPAA compliance.
Titanium body, hypoallergenic interior
2.55mm thick, 7.8mm wide, 3 grams
Sizes: US 6–14
Battery: 8 days (Power Mode), 5 days (Performance)
Charging: 30 mins via wireless charger
ECG, PPG, temp sensor, 3x accelerometer
Bluetooth Low Energy, Airplane Mode
iOS & Android compatible
GDPR & HIPAA compliant
"Landed after a long flight, figured it was just jet lag. Temperature stayed up for three nights, Kira called it recovery, not a problem. Back to normal by night four."
"Thought I handled stress fine. Temperature said otherwise for three weeks straight during a rough month. Bit confronting."
"I learned my 'stressful week' feeling and my 'elevated temperature' week are the same week, every time. Never would have connected those two on my own, I just thought I was tired."
Temperature is one signal in a wider system. Circular Ring 2 reads it alongside your HRV, your sleep stages, your stress, your activity load, your recovery, and your cycle data. The 14+ core features work as one, which is why an overnight temperature rise can be read in context: alcohol, stress, a hard training day, a cycle phase shift, or a long flight catching up.
Your ring reads overnight temperature and heart rate to estimate your fertile window based on the cycle's body signals.
Your Recovery Score shows just how refreshed your body really is, beyond just counting hours.
Early warnings when metrics detect something unusual before you notice.
Tracks breathing rate against your own baseline. Normal resting range: 12–18 breaths per minute.
Light, deep and REM sleep mapped across the night, with the timing and quality of each stage.
Every movement is sorted into low, medium, or high effort based on your heart rate, with a clear daily calorie count beyond workouts.
The ring measures skin temperature continuously through a digital temperature sensor in the inner surface of the ring. The finger is a reliable location for stable temperature readings, with strong arterial flow and consistent sensor contact.
The ring displays your skin temperature value, but that number is not where the useful information lives. Skin temperature shifts too much across the day, across environments, and across individuals to be meaningful as a standalone reading. What matters is the variation against your own personal baseline, tracked night after night.
Yes. The ring tracks temperature 24/7, through the day and through the night. The variation analysis is anchored to your overnight average, because daytime skin temperature is heavily influenced by environment and activity.
The ring reads skin temperature continuously from the finger, and the figure that matters is the deviation from your own 14-day baseline rather than an absolute reading. Fit, cold fingers, low circulation and room temperature all affect a single night, which is why a deviation is only treated as meaningful when it holds across several nights.
A deviation of approximately 0.8 degrees Celsius or more from your baseline is generally worth attention. Smaller variations are normal and reflect daily life. If you see a sustained rise, taking a reading with a clinical thermometer is a sensible next step.
No. Circular Ring 2 is not a medical device and does not detect fever. The ring tracks skin temperature variation, not core body temperature. If you suspect a fever, use a clinical thermometer.
No. Kira AI does not diagnose conditions, prescribe treatment, or replace medical professionals. It translates biometric signals into lifestyle and behavioral guidance you can act on. For anything clinical, the Circular app generates PDF reports and trend summaries designed to be shared with your doctor.
Yes. We encrypt data between your ring, the app, and our cloud systems. We do not sell your health data or use it for advertising, though we process and share limited data when needed to run, protect, and improve the service.
Circular Ring 2 is not intended to diagnose, treat, cure or prevent any disease, and is not for use in an emergency.
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