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Formula for Calculating Your Surface Air Consumption Rate (SAC Rate)

A diver calculates her surface air consumption rate, or SAC Rate, after a scuba dive.

© istockphoto.com, IvanMikhaylov
Plug the data collected during your dives into the appropriate formula below:

• Imperial SAC Rate Formula:
**[ {(PSI Start - PSI End) x 33} ÷ (Depth + 33)] ÷ Time in Minutes = SAC Rate in PSI/min**

• Metric SAC Rate Formula:
**[{(BAR Start - BAR End) x 10} ÷ (Depth + 10)] ÷ Time in Minutes = SAC Rate in BAR/min**

Confused?

If you working in Imperial format:

• "PSI Start" is tank pressure in PSI at the beginning of the dive (method 1) or test period (method 2).

• "PSI End" is the tank pressure in PSI at the end of the dive (method 1) or the test period (method 2).

If you are working in Metric format:

• "BAR Start" is the tank pressure in bar at the beginning of the dive (method 1) or test period (method 2).

• "BAR End" is the tank pressure at the end of the dive (method 1) or the test period (method 2)

For both Metric and Imperial formulas:

• "time in minutes" is the total time of the dive (method 1) or the test period (method 2).

• "Depth" is the average depth during the dive (method 1) or the depth maintained during the test period (method 2).