What this calculator does
Minute ventilation is simply how much air you move per minute: the volume of each breath multiplied by the number of breaths. At rest it usually sits between 5 and 8 litres a minute.
Rate and depth both feed in, but they are not equivalent physiologically. Doubling the rate from 10 to 20 breaths a minute doubles the figure from 5.00 to 10.00 L/min, yet shallow rapid breathing moves proportionally less air into the parts of the lung where gas exchange happens.
The formula
Multiply tidal volume by respiratory rate, converting millilitres to litres. The result is the total volume of air moved in and out over one minute.
| Term | Meaning |
|---|---|
| Tidal volume | The volume of one ordinary breath, around 500 mL in an adult at rest. |
| Respiratory rate | Breaths per minute. |
| Dead space | Airway volume where no gas exchange occurs, which shallow breathing wastes proportionally more of. |
The inputs explained
| Field | What to enter |
|---|---|
| Tidal volume (mL) | Tidal volume in millilitres. Roughly 500 mL is typical for an adult at rest. |
| Respiratory rate (breaths/min) | Respiratory rate in breaths per minute. |
When to use it
Setting ventilator parameters
Tidal volume and rate are the two settings that determine delivered ventilation.
Assessing respiratory effort
A rising minute ventilation indicates increasing work of breathing.
Understanding exercise physiology
Ventilation rises several-fold during exercise through both rate and depth.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How does breathing rate change the total?
The same breath size at four respiratory rates.
| Respiratory rate | Minute ventilation | Typical resting range |
|---|---|---|
| 10 breaths/min | 5.00 L/min | 5 - 8 L/min |
| 14 breaths/min | 7.00 L/min | 5 - 8 L/min |
| 20 breaths/min | 10.00 L/min | 5 - 8 L/min |
| 30 breaths/min | 15.00 L/min | 5 - 8 L/min |
Questions
Why is shallow rapid breathing less efficient?
Because part of every breath only fills the conducting airways, where no gas exchange happens. That dead space is fixed, so the smaller each breath is, the larger the share of it that is wasted.
What is alveolar ventilation?
Minute ventilation less the dead space portion, which is the part that actually reaches gas-exchanging tissue. It is the more physiologically meaningful figure, though harder to measure.
How high can it go during exercise?
Well over 100 L/min in a trained athlete at maximum effort, against 5 to 8 at rest. Both depth and rate increase, with depth rising first as effort builds.
Is a high rate always a concern?
Not by itself. It rises with exercise, fever, anxiety and pain. Persistently rapid breathing at rest is worth medical attention, as is any breathlessness that is new or worsening.
For airflow obstruction from spirometry, see the FEV1/FVC ratio calculator. For cardiovascular workload, see the rate pressure product calculator.