What this calculator does
Tidal volume is the amount of air that moves in or out of the lungs during a single normal breath, without any extra effort. It is one of the basic measurements in respiratory physiology, alongside respiratory rate and minute ventilation, and the three are linked by a simple division: tidal volume equals minute ventilation divided by respiratory rate.
This calculator is a general physiology tool, not a clinical dosing calculator. It answers "how do I calculate tidal volume from the numbers I already have", using whatever minute ventilation and breathing rate you enter. It does not set a ventilation target or recommend a treatment.
The formula
Minute ventilation is the total volume of air breathed in one minute. Respiratory rate is the number of breaths taken in that same minute. Dividing the first by the second gives the average volume of a single breath, the tidal volume, expressed here in millilitres and litres.
| Term | Meaning |
|---|---|
| Minute ventilation | Total volume of air moved by breathing in one minute, usually measured in litres per minute. |
| Respiratory rate | Number of breaths taken per minute. |
| Tidal volume | Volume of air moved in a single normal breath: minute ventilation divided by respiratory rate. |
The inputs explained
| Field | What to enter |
|---|---|
| Minute ventilation (L/min) | Total minute ventilation, in litres per minute. |
| Respiratory rate (breaths/min) | Breathing rate, in breaths per minute. |
When to use it
Working from a spirometry readout
Some spirometers report minute ventilation and rate directly but not tidal volume itself. Dividing the two gives the missing figure.
Physiology coursework
This is the standard textbook relationship between the three basic breathing measurements, useful for working through practice problems by hand.
Comparing rest and exertion
Minute ventilation and rate both rise with exertion. Recomputing tidal volume at each stage shows whether breaths are getting deeper, faster, or both.
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 tidal volume changes with respiratory rate, at a fixed minute ventilation
The same minute ventilation split across a range of breathing rates.
| Respiratory rate | Tidal volume |
|---|---|
| 10 breaths/min | 600 mL |
| 12 breaths/min | 500 mL |
| 14 breaths/min | 429 mL |
| 16 breaths/min | 375 mL |
| 20 breaths/min | 300 mL |
| 24 breaths/min | 250 mL |
How tidal volume changes with minute ventilation, at a fixed rate
A fixed breathing rate with minute ventilation rising, as happens during exertion.
| Minute ventilation | Tidal volume |
|---|---|
| 4 L/min | 286 mL |
| 6 L/min | 429 mL |
| 8 L/min | 571 mL |
| 10 L/min | 714 mL |
| 12 L/min | 857 mL |
| 15 L/min | 1,071 mL |
Questions
How do you calculate tidal volume?
Divide minute ventilation by respiratory rate. If someone moves 6 litres of air per minute at 14 breaths per minute, each breath moves roughly 430 mL.
Is this the same as the ARDSnet lung-protective target?
No. This is the general physiology definition, average breath volume from ventilation and rate. The lung-protective target used in intensive care is a different, weight-based calculation; see the ARDSnet tidal volume calculator for that specific clinical figure.
What is a normal tidal volume?
At rest, a typical adult breath is often quoted around 500 mL, but it varies with body size, activity and individual physiology. This tool reports whatever the entered ventilation and rate imply, not a fixed normal value.
Why does tidal volume matter?
It is one of the three basic quantities describing breathing, alongside rate and minute ventilation. Tracking how it changes can show whether breaths are getting deeper or shallower over time.
For the intensive-care, weight-based lung-protective ventilation target rather than this general physiology figure, see the ARDSnet tidal volume calculator.