Breathing age: how we calculate it
The BreathLife test gives you a level out of 5 and a breathing age. Here is exactly how both numbers are calculated, with every threshold, and what they don't tell you.
Method published October 27, 2026. Same calculations in the web test and in the app.
Definition
The BreathLife breathing age is the age that best matches your breath hold on our scale, measured after a normal exhale and adjusted for smoking and physical activity. It is a wellness indicator, not a medical measure of lung function.
1. The measurement: a breath hold after a normal exhale
Seated and calm, you breathe normally through your nose, then exhale without forcing and hold your breath. The timer stops at the first clear urge to breathe, not at the longest you can hold. This is the principle of Buteyko's "control pause", taken up by Patrick McKeown as the BOLT test.
Why after a normal exhale? With half-full lungs, the time depends less on lung size or willpower than on how quickly the urge to breathe arrives. That is what the test aims to track, week after week.
2. The adjustments
Two answers change the measured time before any calculation. These are BreathLife's choices, to account for factors known to weigh on breathing; the values are not taken from a study.
| Regular smoking | −8 s |
|---|---|
| Occasional smoking | −4 s |
| Regular physical activity | +2 s |
The result is called the adjusted time (never below 0). Example: 22 s measured, occasional smoker, active: 22 − 4 + 2 = 20 adjusted seconds.
3. The level: your adjusted time against the thresholds for your age
Thresholds go down with age: 15 seconds doesn't mean the same thing at 30 and at 75.
| Age | 1. Tight | 2. Shallow | 3. Optimal | 4. Efficient | 5. Exceptional |
|---|---|---|---|---|---|
| Under 40 | up to 12 s | 12 to 25 s | 25 to 38 s | 38 to 60 s | 60 s and more |
| 40 to 49 | up to 10 s | 10 to 20 s | 20 to 38 s | 38 to 60 s | 60 s and more |
| 50 to 69 | up to 10 s | 10 to 18 s | 18 to 35 s | 35 to 50 s | 50 s and more |
| 70 and over | up to 8 s | 8 to 16 s | 16 to 30 s | 30 to 45 s | 45 s and more |
Lower bounds are exclusive: under 40, 12.0 s is still "Tight" and 12.1 s is "Shallow". "Exceptional" starts exactly at the threshold (60 s under 40).
4. The breathing age
Each age group has a reference time. The gap between your adjusted time and that reference time is converted into years, capped by age (table below), smoothed to avoid jumps, then kept within your level's range. The result never goes below 16 or above 95, except under 17 and over 94, where it stays at least one year from your actual age.
Reference times and maximum gaps
| Age | Reference time | Max gap, younger | Max gap, older |
|---|---|---|---|
| 13 to 17 | 30 s | 4 yrs | 8 yrs |
| 18 to 24 | 30 s | 6 yrs | 10 yrs |
| 25 to 29 | 30 s | 8 yrs | 12 yrs |
| 30 to 34 | 25 s | 8 yrs | 12 yrs |
| 35 to 39 | 25 s | 10 yrs | 12 yrs |
| 40 to 49 | 22 s | 10 yrs | 12 yrs |
| 50 to 59 | 20 s | 12 yrs | 12 yrs |
| 60 to 64 | 18 s | 12 yrs | 12 yrs |
| 65 to 69 | 18 s | 14 yrs | 12 yrs |
| 70 to 79 | 15 s | 14 yrs | 12 yrs |
| 80 and over | 12 s | 14 yrs | 12 yrs |
The gap actually reached is then limited by the level's range (opposite).
Range by level
- 1. Tight8 to 12 years older
- 2. Shallow5 to 8 years older
- 3. Optimal5 years younger to 5 years older
- 4. Efficient5 to 10 years younger
- 5. Exceptional10 to 13 years younger (never below 16)
The grid: breathing age by age and adjusted time
Each cell is calculated with the test's own code. Row = actual age, column = adjusted time in seconds.
| Actual age | 5 s | 10 s | 15 s | 20 s | 25 s | 30 s | 40 s | 50 s | 60 s |
|---|---|---|---|---|---|---|---|---|---|
| 25 | 35 | 35 | 33 | 33 | 30 | 25 | 20 | 18 | 16 |
| 35 | 45 | 45 | 43 | 41 | 40 | 32 | 28 | 25 | 25 |
| 45 | 55 | 55 | 53 | 50 | 43 | 41 | 37 | 35 | 35 |
| 55 | 65 | 65 | 62 | 55 | 51 | 50 | 45 | 45 | 45 |
| 65 | 76 | 76 | 71 | 63 | 60 | 60 | 55 | 53 | 53 |
| 75 | 86 | 83 | 80 | 70 | 70 | 70 | 65 | 63 | 63 |
Where do these benchmarks come from? The thresholds, reference times and maximum gaps are BreathLife's calibration choices, built from the BOLT test's reference points and adjusted for age. No study provides age-based reference values for this breath hold: our benchmarks do not come from a population study and have not been clinically validated.
What the breathing age doesn't tell you
- It is not a medical exam. The reference test for lung function is spirometry, performed by a healthcare professional. A spirometry-based "lung age" exists; it is not our number.
- A single measurement varies: sleep, meals, stress, coffee, posture, a blocked nose. Only the trend over several weeks, measured in the same conditions, means something.
- The BOLT test is not scientifically validated, and it is often called "CO₂ tolerance" although one study found no link between breath-hold time and resting exhaled CO₂. What the test reliably tracks is when the urge to breathe arrives.
- The "first clear urge" is still a sensation: two people won't stop at the same moment. The test mainly compares you with yourself.
- Never force a breath hold. If you are pregnant, have a heart or lung condition or epilepsy, or feel unwell, ask your doctor before taking the test or doing the exercises.
Sources
- McKeown P. How to Measure Your BOLT Score. Oxygen AdvantageThe protocol (normal exhale, first clear urge to breathe) and the reference points from under 10 s to 40 s. The author notes the score is mainly for tracking your own progress, not for comparing or diagnosing.
- Nishino T. Pathophysiology of dyspnea evaluated by breath-holding test. Respir Physiol Neurobiol, 2009After a normal exhale, a period without discomfort comes before breathlessness: timing it measures the threshold of breathlessness, whereas a maximal hold measures tolerance.
- Parkes MJ. Breath-holding and its breakpoint. Exp Physiol, 2006Breath-hold duration varies a lot and depends on several factors (lung volume, blood gases, metabolism): no single mechanism explains it.
- Courtney R, Cohen M. Investigating the claims of Konstantin Buteyko. J Altern Complement Med, 2008In 83 adults, breath-hold time did not predict resting exhaled CO₂. It was shorter in people with abnormal spirometry.
- Kiesel K, et al. Development of a screening protocol to identify individuals with dysfunctional breathing. Int J Sports Phys Ther, 2017A hold under 25 s, plus a short questionnaire, flagged most dysfunctional breathing in 51 adults, with many false positives: a screen, not a diagnosis.
- Kowalski T, et al. Body Oxygen Level Test (BOLT) is not associated with exercise performance in highly-trained individuals. Front Physiol, 2024In 49 elite speed skaters, BOLT was not linked to performance. The authors point out the test has not yet been scientifically validated.
- Marko D, et al. Association between BOLT score, aerobic fitness, and physical activity in active university students. J Sports Med Phys Fitness, 2025In 28 students, BOLT was linked neither to fitness nor to reported activity: our activity adjustment (+2 s) is a choice, not a study finding.
- Graham BL, et al. Standardization of Spirometry 2019 Update (ATS/ERS). Am J Respir Crit Care Med, 2019The international standard for spirometry, the reference test for diagnosing and monitoring lung disease.
- Morris JF, Temple W. Spirometric "lung age" estimation for motivating smoking cessation. Prev Med, 1985The medical "lung age", calculated from spirometry, to motivate quitting smoking. Our breathing age borrows the idea of an age, not the measurement.
- Parkes G, et al. Effect on smoking quit rate of telling patients their lung age: the Step2quit randomised controlled trial. BMJ, 2008In 561 smokers, giving a lung age rather than a raw number doubled the 12-month quit rate (13.6% vs 6.4%). It shows an age motivates, not that the number is precise.