To get accurate, lab-grade data from Calibre, it's important to follow a few key steps — especially during setup. Calibre is a precision metabolic measurement device, and unlike causal fitness wearables, it requires proper preparation to function as intended.

We’ve created a Setup Checklist to walk you through everything you need to do before each session. Skipping steps can lead to inaccurate results, while following the full process ensures you're getting the high-quality data Calibre is designed to provide.

You can also visit our Getting Started page for additional best practice and setup guidance.

Calibre continuously measures air flow, breath rate (50 times per second), oxygen and CO2 levels, temperature, and pressure, essential for accurate metabolic analysis. All these quantities allow us to calculate an extensive list of metrics, such as real-time values of calorie burn, VO2, VCO2, minute volume, and more. When these measurements are performed over a period of time we can further calculate useful cumulative, average, and max/min values, such as average breath rate, peak and average VO2 achieved. For a complete list of the metrics Calibre measures and calculates, refer to this PDF.

The calories you burn result from oxygen combining with nutrient fuels in your body - sugar and fats - while producing CO2. By measuring both the oxygen absorbed and the CO2 released by your body, we can determine in real time how much energy is utilized. This scientific technique called "breath calorimetry" has been validated and used by experts for decades.

The Calibre app includes interactive graphs designed to help you dive deeper into your performance data.

To explore your metrics:
• Tap any key metric tile at the top of the screen to display its graph and open its related set of detailed metrics at the bottom. Tapping the tile again will open a pop-up with metric information.
• Long press any key metric tile to pin it to the graph window. This allows you to overlay multiple key metrics for comparison. Each pinned metric is plotted on its own colored Y-axis. Select a key metric tile to switch the Y-axis labels.
• Long press any pinned key metric to unpin it.
• Tap any detailed metric at the bottom to open its pop-up with additional information.

Tip: Experiment with different overlays to gain deeper insights into your performance trends!

In earlier versions of the Calibre app, Fat Burn % and Carb Burn % always added up to 100%, using a common formula based on your Respiratory Exchange Ratio (RER = VCO₂ / VO₂):
• Carb Burn % = 0% when RER < 0.7 and 100% when RER > 1.0
• Fat Burn % = 100 – Carb Burn %

While this model is widely used, it’s a simplification. In reality, protein also contributes to energy metabolism. Protein metabolism isn’t directly measurable from breath, but it can be estimated based on factors like body weight and an average diet. In developing the new Calibre app, we consulted with experts in the field. Together, we concluded that including estimated protein contribution provides a more accurate representation of your energy usage.

As a result, Fat Burn % + Carb Burn % now typically adds up to less than 100%—the difference reflects estimated protein metabolism.

Note: Protein metabolism can be measured more precisely through laboratory testing, but not in real time during breath analysis.

Tidal volume refers to the amount of air you inhale or exhale in a single breath. When measuring exhaled gases like carbon dioxide (CO2), there are different ways to analyze the breath. One common measure is end-tidal CO2 (EtCO2) — sometimes referred to as end-tidal volume measurement — which reflects the concentration of CO2 at the very end of an exhalation — this is typically where CO2 levels peak.

Most quantities of interest in metabolic measurements, however, are based on FeCO2, which represents the total or average CO2 concentration across the entire exhaled breath. Calibre is designed to calculate accurate average CO2 levels (FeCO2) by analyzing and averaging exhaled air over time, rather than isolating the brief window at the end of each breath needed for EtCO2 measurement.

This design choice helps improve overall accuracy for metabolic assessments, though it means Calibre does not provide specific EtCO2 values in its current form.

For maximum accuracy, we strongly recommend performing a Baseling before each use. This ensures the sensors are properly warmed, resulting in the most precise measurements.

How to Perform a Baseline:
1. Press and hold the front button for 10 seconds until you see a triple-flash yellow light.
2. Let the device rest for 1 minute.
3. Charge the device for at least 30 minutes—this step is essential. The O₂ sensor requires a full 30 minutes on the charger to warm up properly, even if the battery is already charged. Skipping this may lead to inaccurate readings.

Yes, utilizing our validated protocol allows you to measure and calcualte your VO2Max accurately.

Be aware that the first few minutes of any session may produce unstable readings as the sensors stabilize. It's best to disregard data from this initial period.

Like many sensor-based devices, Calibre can be affected by water condensation, and its built-in protections have their limits. To ensure accurate data and protect your device, strictly follow the session limits below:

• Moderate intensity (≤ 60 L/min breath volume, up to 10 METs): Up to 90 minutes max per session.
• High intensity (> 60 L/min breath volume): Maximum 25 minutes, including warm-up, cool-down, and all activity.
• Back-to-back sessions must be treated as a single extended session in terms of water-buildup. Allow at least 1 hour between sessions to let the sensor dry fully. Exceeding these limits may result in irreversible sensor damage and will void your warranty.

Exceeding these limits may result in irreversible sensor damage and will void your warranty.

METs, or Metabolic Equivalents, are a measure of the energy cost of physical activities, such as cycling, running, or other exercises. Many mainstream training devices, like treadmills, stationary bikes, and rowing machines, display this metric.

One MET is defined as the energy expenditure at rest, typically around 3.5 mL of oxygen consumed per kilogram of body weight per minute. In cycling, METs are used to quantify the intensity of the activity.Understanding and utilizing METs will vary depending on your fitness level.

For example, in cycling a relatively fit person could see the following:
• Light cycling (e.g., leisurely ride): Around 3-6 METs.
• Moderate cycling (e.g., a steady pace): Around 6-8 METs.
• Vigorous cycling (e.g., racing or intense effort): 8+ METs.

Professional cyclists often reach very high MET levels due to the intensity and duration of their training and competition. MET levels for pro cyclists can vary significantly depending on the activity and effort level:
1. Low-Intensity Training or Recovery Rides:
• METs: 6-8
• Examples: Easy rides or warm-up/cool-down sessions where the intensity is kept low.

2. Moderate-Intensity Training:
• METs: 8-12
• Examples: Steady-state rides or endurance training at a moderate pace.
3. High-Intensity Training:
• METs: 12-16
• Examples: Tempo rides, time trials, or sustained climbing efforts.
4. Maximal Effort (e.g., Sprints, Hill Climbs):
• METs: 16+
• Examples: All-out efforts during a race, sprint finishes, or intense hill climbs.

In peak performance scenarios, such as during a grueling stage of a grand tour, pro cyclists can sustain MET levels above 16 for extended periods, reflecting their exceptional aerobic capacity and conditioning.

Training with METs helps cyclists (athletes) gauge and adjust the intensity of their workouts, monitor energy expenditure, and tailor training programs to meet specific fitness goals.

Yes, you may export your session data as CSV files through your personal web-based portal:
1. Go to the web-based portal
2. Log in with your Calibre app credentials.
3. Select the download button next to the session or open the session and select “Download CSV”."

If your device is unresponsive, follow these charging guidelines first:Use the provided USB-C cable (avoid third-party cables).

Use a standard 5V-2A charging adapter (avoid accelerated adapters).Plug directly into a wall socket (avoid external charging devices).

Charge for at least 2-3 hours, regardless of LED light status.

If the device remains unresponsive, perform an overnight charge (minimum 8 hours) and follow these steps:
• Charge the device overnight or for a minimum of 8 hours using the provided cable and a standard 5V-2A charging block plugged directly into a wall socket.
• The next morning, unplug the device from the charger.
• Press and hold the front button on your device for 10 seconds until you see a triple flash of yellow light on your device. If no flash occurs, continue to the next step.
• Let your device rest for 10 minutes.
• Charge the device for at least 30 minutes, even if it is already fully charged. This step is crucial, as the O2 sensor needs at least 30 minutes on the charger to warm up properly, regardless of the battery status.

If your device still does not respond or display a white light when pressing the button, please contact us at info@calibrebio.com for further assistance.

If your device displays a solid or blinking red light, follow these charging guidelines first:
• Use the provided USB-C cable (avoid third-party cables).
• Use a standard 5V-2A charging adapter (avoid accelerated adapters).
• Plug directly into a wall socket (avoid external charging devices).
• Charge for at least 2-3 hours, regardless of LED light status.

If the red light persists, perform an overnight charge (minimum 8 hours) and follow these steps:
• Charge the device overnight or for a minimum of 8 hours using the provided cable and a standard 5V-2A charging block plugged directly into a wall socket.
• The next morning, unplug the device from the charger.
• Press and hold the front button on your device for 10 seconds until you see a triple flash of yellow light on your device. If no flash occurs, continue to the next step.
• Let your device rest for 10 minutes.Charge the device for at least 30 minutes, even if it is already fully charged. This step is crucial, as the O2 sensor needs at least 30 minutes on the charger to warm up properly, regardless of the battery status.

If the issue persists, please contact us at info@calibrebio.com for further assistance.

The device's battery life varies based on usage but typically lasts up to 36 hours on a full charge.

If you believe your battery is depleting faster than normal, the first thing to do is ensure you are following these charging practices:
• Use the provided USB-C cable (avoid third-party cables).
• Use a standard 5V-2A charging adapter (avoid accelerated adapters).
• Plug directly into a wall socket (avoid external charging devices).
• Charge for at least 2-3 hours, regardless of LED light status.Put the device in sleep mode when not in use (press and hold the button for 3 seconds until the light fades).

If you’re following all of the above charging practices and your battery still depletes faster than intended, please conduct an battery test:
• Charge the device overnight or for a minimum of 8 hours using the provided cable and a standard 5V-2A charging block plugged directly into a wall socket.
• Disconnect the device from the charger and promptly place it in sleep mode. (To activate sleep mode, press and hold the device's button for approximately 3 seconds until the light illuminates, then release the button once the light fades).
• After 24 hours, connect your device to the app, note the battery percentage, and report it to the Calibre team at info@calibrebio.com.

The shipping rate will vary based on your zip code and country. Calibre does not cover VAT, customs, or import taxes. When you make your purchase, we are unable to calculate your local VAT, customs, or import taxes, so please ensure that you perform your own due diligence in paying these charges upon receiving your package.

If you received a product that is damaged or faulty, you may exchange it for a new one within 30 days.