The pocket spirometer with a gold standard transducer is an essential tool for freedivers.

Features and Usage

The Carefusion Micro is the industry standard spirometer for lung volume measurements.  It can measure both:

  • FVC = forced vital capacity, the amount of air you exhale after a full inhalation (more typically referred to as vital capacity)
  • FEV1 = the volume of air you can exhale in 1 second

A spirometer is an indispensable training tool for freedivers and spearfishermen.  By measuring your lung volume with a personal spirometer on a day-to-day basis, you can track large and significant volume changes, which occur as a result of stretching, training, or actual diving.  This can help you optimize your stretching and training exercises for improved performance in the water.

For deep freedivers, a spirometer is also essential for safe diving.  If you had previously dove a personal best the previous season, it is very important to ensure that your lung volume (today) is as much, or more, as your lung volume was when you did your earlier personal best.  If you are out of shape or inflexible, the spirometer will alert you that you are nowhere near your previous volume, and this is a big warning that you should not attempt to dive as deep as you did before, until you get your lung volume back up.

For divers who use lung packing (buccal pumping or "carpe" as the French call it), the spirometer is even more useful.  With the spirometer you can measure how much extra air you get with packing, and whether those last few difficult packs are even worth the time and effort.  Tracking your full volume with lung packing, you will notice even greater seasonal changes than someone who tracks their volume without packing.  At the end of the season you may find your fully packed volume is as much as 2L more than your fully packed volume at the start of the season.

For deep equalizing, the spirometer has its uses as well.  Larger lungs typically mean easier equalizing at depth, but the Carefusion Micro spirometer is so accurate that you can even use it to measure your mouth fill volume, when learning the 'mouth fill' technique for deep equalization.  A good mouth fill technique will result in over 500ml (0.5L) of air in your mouth and cheeks.  With the Carefusion spirometer you can actually measure your mouthfill volume, and then you can try different techniques to fill your mouth to get a 'bigger' mouth fill and equalize deeper than ever before.

Although it appears to have a significant up front cost, the Micro spirometer is durable.  Freediving pioneer Eric Fattah is still using the same Micro spirometer that he purchased in 2001 -- it still works flawlessly 10 years later, making it an incredible value.  Considering that he has gone through about 30 masks and 20 monofins in the same amount of time, the spirometer in the end was much less expensive.

Spirometer Functionality

  • Measures FVC and FEV
  • Gold standard transducer
  • No user calibration adjustment required
  • Easy to use, clean and maintain
  • Spare mouthpiece
  • Predicted value lung function calculator included
  • Complete with sturdy carrying case
  • Battery-low indicator
  • Runs on single 9V battery

Hardware Specs

  • Measurements: FVC and FEV
  • Resolution: 10ml
  • Flow range: 0.2 – 15.00 liters/second
  • Accuracy: ± 3% (ATS diagnostic standard)
  • Custom three digit liquid crystal display
  • Dimensions: 16.51cm x 6.35cm x 5cm (6.5”x2.5”x1”)
  • Weight: 227g (8 ounces)
  • Battery-low indicator alarm
  • Power supply: single 9V battery
  • Operating temperature: -1ºC – 40ºC (30-104F)
  • Operating humidity: 30-90% RH
  • Storage temperature: -20ºC – 70ºC (-4 – 158F)
  • Storage humidity: 10-90% RH


Comes in convenient, sturdy carrying case
Two mouthpieces
9V battery

Click here to download the spirometer manual (PDF)

Carefusion Micro Spirometer

  • The Carefusion Micro Oximeter retails for $399 CAD
  • Availability: OUT OF STOCK