SAC — Surface Air Consumption

Surface Air Consumption (SAC) is your breathing rate measured at the surface. It tells you how many liters of air you use every minute.

Divers use this number to calculate how much gas remains in a tank. I used my SAC rate to plan long deco stops in Komodo back in 2018. A typical value for a relaxed diver is 15 to 20 liters per minute. If your rate jumps to 30 liters, you are likely working too hard or panicking.

High currents often spike this number. You should monitor your pressure gauge every 5 minutes so that you avoid running low on gas. Do not rely on a single dive for an accurate calculation because stress changes your breathing. Always check your depth before calculating your remaining air time.