Disclaimer
Warning! DO NOT USE THIS INFORMATION
FOR DIVE PLANNING! Seek professional advice before using this information!
Formula
SAC Rate = ((psi start - psi end) * (tank rated size / tank rated pressure))
/ (1 + (depth / 33))
General Information
If you read online you will see there is a fair debate about the depth
parameter.
The general consensus seems that average depth of the dive should be used instead
of the maximum depth.
Also note that sac rates are not percise measurements of how much air you use per
minute as there are other considerations such as workload, stress, equipment, etc.
What is a good SAC rate?
SAC rate varies for everyone based on how big you are, if you are male
or female, what equipment you use, etc.
There is no general good SAC rate.
However the lower the number the less air you used per minute.