SAC rate calculator
Enter your cylinder and dive data to get your surface air consumption in bar/min (SAC, cylinder-dependent) and in litres/min (RMV, cylinder-independent). No sign-up required.
SAC
1.19 bar/min
RMV
14.3 L/min
Gas used
150 bar · 1800 L
Formula: SAC = (start pressure − end pressure) / dive time / (average depth / 10 + 1); RMV = SAC × cylinder volume. Results are indicative — always plan within your training and agency procedures.
Let DiveLog do the maths for you
Import dives straight from your dive computer and DiveLog calculates average depth, SAC and gas usage for every dive automatically.
How to calculate your SAC rate
- 1. Note the pressure at the start and at the end of the dive.
- 2. Record the total dive time in minutes.
- 3. Take the average depth from your dive computer (not the maximum depth — it would overestimate the ambient pressure).
- 4. Enter the cylinder volume in litres to convert your SAC into an RMV.
Frequently asked questions
What is a SAC rate?
SAC (surface air consumption) is how much gas you breathe per minute at the surface, expressed in bar/min for a given cylinder. It lets you compare dives made at different depths.
What is the difference between SAC and RMV?
SAC is measured in bar/min and depends on the cylinder you use. RMV (respiratory minute volume) is measured in litres/min and is cylinder-independent, so it is the better number to reuse when planning with a different tank.
How do you calculate SAC rate?
SAC = (start pressure − end pressure) / dive time / (average depth / 10 + 1). Multiply the result by the cylinder volume in litres to get your RMV.
What is a good SAC rate for a diver?
Most recreational divers land between roughly 12 and 20 litres/min RMV. Lower numbers usually reflect better trim, buoyancy and relaxation rather than a target to chase.