Scuba Depth & Pressure Calculator

Convert depth to ambient pressure, pressure back to depth and calculate how much surface-equivalent breathing gas a scuba cylinder contains. The page uses the standard training approximations of one additional atmosphere every 10 meters or 33 feet of seawater.

Depth to Pressure Calculate Depth Cylinder Gas Volume

Calculator 1

Depth to ambient pressure

Enter a depth and see the approximate absolute pressure and the breathing-gas consumption multiplier at that depth.

Ambient pressure-

Depth meters-

Depth feet-

Gas-use multiplier-

Calculator 2

Ambient pressure to depth

Reverse the relationship: enter absolute pressure in ATA and calculate the equivalent seawater depth.

Depth meters-

Depth feet-

Relative gas demand-

Boyle volume-

Calculator 3

Scuba cylinder gas volume

Estimate surface-equivalent gas in a cylinder and the usable amount above a selected reserve pressure.

Gas in cylinder-

Usable above reserve-

Metric equivalent-

Imperial equivalent-

How the Math Works

Depth, pressure and cylinder formulas

Depth to pressure: metric ATA = (depth in meters / 10) + 1. Imperial ATA = (depth in feet / 33) + 1.

Pressure to depth: meters = (ATA - 1) x 10. Feet = (ATA - 1) x 33.

Metric cylinder gas: surface-equivalent liters = cylinder water volume in liters x pressure in bar.

Imperial cylinder gas: available cubic feet = rated capacity x (current pressure / rated service pressure).

Boyle relationship: at constant temperature, gas volume changes inversely with absolute pressure.

Practical Meaning

Why pressure matters to divers

At 20 meters the surrounding pressure is approximately 3 ATA, so a diver breathing at the same surface ventilation rate consumes about three times the surface-equivalent gas volume per minute. Pressure also changes the volume of flexible gas spaces, which is why equalization, buoyancy control and controlled ascents are fundamental scuba skills.

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