Your RMV Rate, How To Calculate And Use It To Be A Better Diver!

By Jose Cernuda

How much gas did you have left after your last dive? Do you know the precise number as a volume? Do you know how much your average consumption rate is? While It’s extremely common for divers to ask each other how much gas they had left after a dive many people express what was left in terms of PSI or BAR. And while that’s helpful if both you and your buddy were using the same tank it becomes tricky if you’re using different cylinders.

The most precise way to know is using your RMV. If you are serious about diving and improving your diving then you need to know this number. There is a famous business quote from Peter Drucker “If you can’t measure it, you can’t manage it”. This is certainly true of your breathing rate. If you’ve ever wondered about how to measure, use and calculate your breathing rate you’re going to want to read on.

What is RMV?

RMV stands for Respiratory Minute Volume. It is a way divers express how much gas was consumed during a dive. RMV is always expressed as a volume. In the Imperial system, we use cubic feet per minute to express RMV. In the Metric system, RMV is expressed in Liters per minute. RMV is usually standardized as a measurement on the surface. This means that if, for example, you have an RMV of 1 cubic foot per minute  (28 liters per minute) on the surface you’ll use 2 cubic feet (56 liters) at 33 feet (10 meters), 3 cubic feet (84 liters) at 66 feet (20 meters), etc.. because of Boyles Law and the increase in atmospheric pressure. The illustration below shows how the increase in depth/pressure also affects your breathing rate.