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Calculate scuba air usage rate at depth from SAC rate and dive depth. Estimate PSI per minute, cu ft consumed, and remaining dive time from tank pressure.
Plan safe recreational scuba dive profiles from air supply, depth, and SAC rate. Estimate bottom time, turn pressure, and remaining gas at ascent.
Calculate enriched air nitrox MOD, EAD, and partial pressure of oxygen (ppO2) for scuba diving. Plan safe oxygen exposure limits at depth.
Subtract ending tank pressure from starting pressure to find total pressure consumed during the dive. Use average depth, not maximum depth, for accurate SAC calculations.
PSI used = Starting PSI − Ending PSIMultiply pressure used by internal tank volume and divide by rated working pressure to convert PSI drop into actual cubic feet of gas consumed underwater.
Air (cu ft) = (PSI used × Tank size) ÷ Max PSIDivide air consumed by time and absolute pressure (1 ATA + depth in atmospheres). For imperial depth in feet, divide depth by 33 to get atmospheres of water pressure above ambient.
SAC = Air consumed ÷ (Time × (Depth/33 + 1))Updated: July 2026
After a 30-minute dive from 3000 to 2200 PSI at 60 ft average depth, SAC calculates to roughly 0.8 cu ft/min — useful for planning a second dive on the same tank.
Two divers on identical profiles with different end pressures reveal fitness and stress differences. Lower SAC indicates better buoyancy control and relaxed breathing.
Knowing your SAC rate lets you estimate how many tanks to charter for a week of diving when fills are limited at a liveaboard or remote resort.
Surface Air Consumption (SAC) rate measures how much air you breathe at the surface, normalized from a dive at depth. Enter starting and ending tank pressure, tank volume, dive time, and average depth to calculate your personal SAC rate in cubic feet per minute.