Scuba Surface Air Consumption Calculator

About this calculator

A diver's Surface Air Consumption (SAC) rate measures how much breathing gas they use per minute, normalized to what that consumption would be at the surface — this normalization matters because gas use scales with ambient pressure at depth, so the same diver breathes noticeably more gas per minute at 20 meters than at the surface. Ambient pressure in atmospheres absolute (ATA) is found with ATA = depth ÷ 33 + 1 for saltwater, and dividing actual consumption by that ATA value strips out the depth effect.

This calculator takes the gas used (in psi), dive time, and average depth to compute SAC rate in psi per minute. It's a core planning number for certified scuba divers, used to estimate how long a given tank will last on a future dive, plan gas reserves for deeper or longer dives, and track fitness and air-consumption efficiency over time — a skill emphasized in advanced and technical diving training.