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Dive Planning

SAC Rate Calculator

Calculate your Surface Air Consumption rate from dive data to improve gas planning and dive safety.

Dive data

SAC is a pressure rate, so these four readings are all it needs.

BAR

Allowed range: 170 to 275 BAR.

BAR

Allowed range: 20 to 140 BAR.

min

Allowed range: 10 to 120 min.

m

Allowed range: 5 to 40 m.

Convert to RMV

Your cylinder does not change the SAC rate above. It is needed to turn that pressure rate into a tank-independent RMV volume, so these values are carried over to the RMV calculator.

L

Allowed range: 5 to 20 L.

BAR

Allowed range: 170 to 250 BAR.

Tank size presets
Calculate RMV with this cylinder
About SAC Rate

Surface Air Consumption (SAC) rate is how fast your cylinder pressure drops per minute, normalized to surface pressure. It is a key metric for gas planning, but because it is measured in pressure it stays tied to the cylinder you dived — convert it to RMV to compare across cylinders.

This workflow uses a conventional linear pressure-volume estimate. Real-gas effects at high cylinder pressures can materially change the inferred breathing volume. A correction needs the cylinder gas temperature at both pressure readings.

Compare conventional and real-gas cylinder estimates
SAC=ΔPt DFΔP=Pstart−PendDF=d+CDCD\begin{aligned} \text{SAC} &= \frac{\Delta P}{t \, D_F} \\[0.5em] \Delta P &= P_{\text{start}} - P_{\text{end}} \\[0.5em] D_F &= \frac{d + C_D}{C_D} \end{aligned}

Where

ΔP\Delta P
pressure used (bar)
tt
dive time (minutes)
DFD_F
depth factor: absolute pressure at average depth (ATA)
dd
average depth (m)
CDC_D
10 m of seawater per atmosphere
Tips to Improve

• Perfect your buoyancy

Minimize unnecessary movements and finning

• Breathe continuously and comfortably

Never hold or deliberately restrict your breath to save gas

• Streamline your gear

Reduce drag and maintain proper trim

• Stay relaxed and calm

Stress and anxiety increase air consumption

Result

1.10 bar/min

Frequently Asked Questions

What is SAC rate in scuba diving?
In DiveCalc, SAC (Surface Air Consumption) is the cylinder-pressure drop per minute normalized to surface pressure, expressed in bar/min or PSI/min. Because it depends on the cylinder, convert it to RMV before comparing different cylinders.
What is a good SAC rate?
There is no universal pressure-based SAC value because bar/min or PSI/min depends on cylinder size and working pressure. Compare your own SAC on the same cylinder in similar conditions, or convert it to RMV for cross-cylinder comparisons. Use a conservative value for planning.
How do I calculate my SAC rate?
Subtract ending cylinder pressure from starting pressure, divide by dive time, then divide by the average ambient pressure in ATA (depth ÷ 10 + 1 in meters, depth ÷ 33 + 1 in feet). For example, 200 to 70 bar over 45 minutes at an average 15 m is 130 ÷ (45 × 2.5) ≈ 1.16 bar/min; 3,000 to 1,000 psi over 45 minutes at an average 50 ft is about 17.7 psi/min. Cylinder size and working pressure are needed only when converting SAC to RMV.
What is the difference between SAC and RMV?
Terminology varies. DiveCalc uses SAC for surface-normalized cylinder pressure per minute and RMV for surface-equivalent gas volume per minute. SAC is cylinder-dependent; RMV can be used across cylinder configurations.
How can I improve my SAC rate?
Improve buoyancy, trim, streamlining, fitness, and comfort to reduce unnecessary workload. Breathe continuously and comfortably; never hold or deliberately restrict your breath to save gas. Track comparable dives and use conservative rates for planning.

Related Guides

Gas planning & consumption

Understanding SAC Rate: Why It Matters for Every Diver

Gas planning & consumption

SAC Rate vs RMV: What's the Difference and When to Use Each

Gas planning & consumption

Diving Gases Explained: Air, Nitrox, Trimix, Heliox, Oxygen, and Argon

Related Diving Tools

Gas Management

Cylinder Capacity Calculator

Dive Planning

Dive Unit Converter

Dive Planning

Gas Consumption Planner

Reference Data

Reference

Scuba Cylinder Specifications

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