surface air consumption

A calculator for how long the cylinder gas lasts.

Enter the depth, the cylinder size, the pressure, and your SAC rate. This plan splits the fill: 65% on the bottom, 10% for the ascent and safety stop, and 25% kept for the surface.

Dive plan

1 Main dive

200 bar → 70 bar

Terpakai 65% dari 200 bar

26 menit

Bottom time at the depth you entered. The deeper you are, the shorter this gets.

2 Start the ascent and safety stop

70 bar → 50 bar

Terpakai 10% dari 200 bar

3.3 menit naik · 3 menit di 5 m

Ascend no faster than 9 m/min, stop for 3 minutes at 5 m, then go to the surface.

3 Mandatory reserve at the surface

50 bar

Tersisa 25% dari 200 bar

Not used

The pressure that still has to be in the cylinder when you reach the surface.

Jatah naik 20 bar (10% dari 200 bar). Dari 30 m, dengan naik paling cepat 9 m/min lalu 3 menit di 5 m, pemakaiannya sekitar 16.0 bar. Sisa jatah itu tetap di tabung, di atas cadangan.

Apabila tabung kamu diisi 200 bar, maka 130 bar untuk di dasar, jadi tekanan tabung turun dari 200 bar ke 70 bar. Di 30 m kamu bisa tinggal kira-kira 26 menit. Lalu 20 bar untuk naik dan berhenti 3 menit di 5 m, jadi tekanan tabung turun dari 70 bar ke 50 bar. Sisa 50 bar jangan dipakai. Itu cadangan yang harus masih ada saat kamu sudah di permukaan. Di kedalaman ini udara berkurang 5.0 bar tiap menit, jadi semakin dalam, waktu di dasar semakin sedikit.

What the words mean

SAC: SAC stands for Surface Air Consumption, the gas you use per minute at the surface, in litres. At depth, that rate is multiplied by the water pressure.
Cylinder volume: The cylinder's water capacity, in litres. A 12 L cylinder filled to 200 bar holds 2,400 L of gas.
Start pressure: The pressure you read on the cylinder when the dive starts, in bar. The plan percentages are taken from this number.
65 / 10 / 25: Shares of the start pressure. A 200 bar fill means 130 bar on the bottom, 20 bar for the ascent, and a 50 bar reserve. Any other fill follows the same percentages.
Reserve: 25% of the start pressure. On a 200 bar fill that is 50 bar, and it is not used on the bottom or on the way up.
Depth: A steady bottom depth, in metres. Every 10 m adds 1 bar, so the bottom gas runs out faster.
Ascent: No faster than 9 m/min up to 5 m, a 3-minute stop, then up to the surface. Ascent gas is calculated at the average pressure on the way up, not at the bottom pressure. If the way up needs more than 10%, you leave the bottom earlier.
Minutes: Bottom time from the 65% budget, rounded down. This is how long you stay on the bottom before you start up, not how long until the cylinder is empty.

A planning aid, not a substitute for training or a dive computer.