Scuba Tank Sizes Chart: AL80, HP100 and Steel Cylinders

A scuba cylinder has two sizes. Metric divers give its water volume, the space inside it (an AL80 is 11.1 L). US divers give the gas it holds at its working pressure, expanded to the surface (the same AL80 holds about 77 cubic feet, sold as 80). Pick a cylinder for its spec sheet, or sort the full chart below.

The formula

V_{gas} = \frac{V_{water} \times p_{work}}{Z (p_{work}, T) \times 1.01325}

V_water in litres, p_work the working pressure in bar, 1.01325 bar the one atmosphere the gas is expanded to. Z is the compressibility of air at that pressure: at 15 °C (EN/ISO) for the metric figure, at 70 °F for the US true capacity in cubic feet. With Z = 1 this is the ideal-gas sum behind most marketed names.

Worked example

An AL80 has a water volume of 11.1 L and a working pressure of 3000 psi (207 bar). Its name says 80 cubic feet.

1The ideal-gas sum, water volume times working pressure over 1.01325 bar, gives 2,266 L (80.0 ft³).
2Air at 207 bar packs less tightly than that. With the real-gas compressibility at 70 °F, the convention of Luxfer's and Faber's HP spec sheets, the gas at 1 atm is 77.4 ft³.
3At 15 °C, the EN/ISO convention metric divers use, it is 2,204 L (77.8 ft³).
4A Steel 12L 232 (12 L, 232 bar) holds 2,629 L, about 19% more gas than the AL80.

Scuba tank sizes chart

All 38 cylinders in the dataset. Gas is the real-gas amount at the working pressure, expanded to 1 atm; rated is the cubic-foot name a US cylinder is sold under. Buoyancy is the cylinder with its valve, alone in water, in kg: negative sinks, positive floats. Tap a column to sort.


AL 12L	Aluminum	12 L	200 bar · 2901 psi	2,315 L	81.3 ft³	–	−0.4	+2.5
AL13	Aluminum	1.9 L	207 bar · 3000 psi	377 L	13.2 ft³	13 ft³	−0.8	−0.3
AL19	Aluminum	2.87 L	207 bar · 3000 psi	570 L	20.0 ft³	19 ft³	−0.6	+0.1
AL30	Aluminum	4.3 L	207 bar · 3000 psi	854 L	30.0 ft³	30 ft³	−0.7	+0.2
AL40	Aluminum	5.7 L	207 bar · 3000 psi	1,132 L	39.7 ft³	40 ft³	−0.3	+1.4
AL50	Aluminum	6.9 L	207 bar · 3000 psi	1,370 L	48.1 ft³	50 ft³	−1.1	+0.7
AL63	Aluminum	9 L	207 bar · 3000 psi	1,787 L	62.8 ft³	63 ft³	−1.1	+1.2
AL72	Aluminum	10 L	207 bar · 3000 psi	1,986 L	69.7 ft³	72 ft³	−1.0	+1.5
AL80	Aluminum	11.1 L	207 bar · 3000 psi	2,204 L	77.4 ft³	80 ft³	−0.8	+2.0
AL100	Aluminum	13.2 L	228 bar · 3300 psi	2,844 L	99.9 ft³	100 ft³	−2.1	+1.4
CCR 2.7L	Steel	2.7 L	232 bar · 3365 psi	592 L	20.8 ft³	–	−1.1	−0.3
CCR 2L	Steel	2 L	200 bar · 2901 psi	386 L	13.5 ft³	–	−0.9	−0.4
CCR 2L 232	Steel	2 L	232 bar · 3365 psi	438 L	15.4 ft³	–	−1.1	−0.5
CCR 3L	Steel	3 L	200 bar · 2901 psi	579 L	20.3 ft³	–	−1.9	−0.8
CCR 3L 232	Steel	3 L	232 bar · 3365 psi	657 L	23.1 ft³	–	−2.0	−0.9
HP80	Steel	10.2 L	237 bar · 3442 psi	2,277 L	80.0 ft³	80 ft³	−3.7	−0.3
HP100	Steel	12.9 L	237 bar · 3442 psi	2,879 L	101.2 ft³	100 ft³	−3.8	+0.3
HP117	Steel	15 L	237 bar · 3442 psi	3,348 L	117.6 ft³	117 ft³	−4.1	+0.8
HP119	Steel	14.8 L	237 bar · 3442 psi	3,304 L	116.1 ft³	119 ft³	−4.8	−0.7
HP120	Steel	15.3 L	237 bar · 3442 psi	3,415 L	120.0 ft³	120 ft³	−5.5	−1.1
HP130	Steel	16 L	237 bar · 3442 psi	3,571 L	125.5 ft³	130 ft³	−5.8	−1.0
HP133	Steel	17 L	237 bar · 3442 psi	3,795 L	133.3 ft³	133 ft³	−4.1	+1.4
LP50	Steel	7.8 L	182 bar · 2640 psi	1,382 L	48.5 ft³	50 ft³	−2.0	−0.3
LP72	Steel	13.2 L	155 bar · 2250 psi	2,020 L	70.9 ft³	72 ft³	−3.0	−0.6
LP85	Steel	13 L	182 bar · 2640 psi	2,303 L	80.8 ft³	85 ft³	−1.7	+1.6
LP95	Steel	15 L	182 bar · 2640 psi	2,657 L	93.3 ft³	95 ft³	−3.6	−0.2
LP104	Steel	16.6 L	182 bar · 2640 psi	2,940 L	103.2 ft³	104 ft³	−5.0	−1.5
LP108	Steel	17 L	182 bar · 2640 psi	3,011 L	105.7 ft³	108 ft³	−2.3	+2.1
Steel 3L 300	Steel	3 L	300 bar · 4351 psi	805 L	28.3 ft³	–	−1.9	−0.8
Steel 7L 232	Steel	7 L	232 bar · 3365 psi	1,534 L	53.9 ft³	–	−2.8	−0.8
Steel 8.5L 232	Steel	8.5 L	232 bar · 3365 psi	1,862 L	65.4 ft³	–	−3.1	−0.7
Steel 10.5L 232	Steel	10.5 L	232 bar · 3365 psi	2,300 L	80.8 ft³	–	−3.8	−0.8
Steel 10L 232	Steel	10 L	232 bar · 3365 psi	2,191 L	77.0 ft³	–	−3.4	−0.6
Steel 12L 200	Steel	12 L	200 bar · 2901 psi	2,315 L	81.3 ft³	–	−3.1	−0.2
Steel 12L 232	Steel	12 L	232 bar · 3365 psi	2,629 L	92.4 ft³	–	−3.8	−0.5
Steel 12L 300	Steel	12 L	300 bar · 4351 psi	3,221 L	113.3 ft³	–	−5.5	−1.5
Steel 15L 232	Steel	15 L	232 bar · 3365 psi	3,286 L	115.4 ft³	–	−4.2	0.0
Steel 18L 232	Steel	18 L	232 bar · 3365 psi	3,943 L	138.5 ft³	–	−5.5	−0.5

Data: the Dive Kit open cylinder dataset, version 2026.10.30.1, at open.divekit.app, under the MIT licence. Representative values for each cylinder type; a given cylinder differs with maker, valve and hardware.

How Dive Kit computes this

The water volume, working pressure, empty weight and buoyancy of each cylinder come from the Dive Kit open cylinder dataset, published at open.divekit.app under the MIT licence. The gas capacity is computed, not stored: Dive Kit divides the ideal-gas figure by the compressibility factor Z of air, built from NIST reference data for nitrogen and oxygen.

Two conventions, as in the app. In metric the capacity is free gas at 15 °C, the EN/ISO reference Dive Kit uses for all gas content maths, in whole litres. In imperial it is the gas at 70 °F, the convention Luxfer and Faber HP spec sheets use for true capacity, in tenths of a cubic foot, so it can be set beside the chart for your cylinder. Not every sheet follows it: some low-pressure steel sheets quote a figure closer to the ideal-gas sum. An AL80 reads 77.4 ft³ that way, Luxfer's published figure, against the 80 of its name. Our article on cylinder capacity walks through the two conventions with worked numbers.

Buoyancy is the cylinder alone in water at three fills (full, 50 bar and empty), with its valve, without regulator, bands or rigging. The swing between full and empty is the gas you breathe, which is why an aluminium cylinder that sinks when full floats at the end of a dive. The scuba weight calculator uses these same figures.

The app screen for this tool is documented in the user guide: Cylinder Database in the Dive Kit guide.

How much air does an AL80 hold?

Its name says 80 cubic feet, the ideal-gas figure. With the real compressibility of air at 3000 psi and 70 °F, the convention Luxfer and Faber HP spec sheets use, it holds 77.4 ft³, the true capacity Luxfer publishes. In metric terms it is an 11.1 L cylinder at 207 bar; pick it in the calculator for both.

How long does an AL80 last?

It depends on depth and on how fast you breathe. At an SRMV of 20 L/min and 18 m (59 ft) of EN 13319 water, a full AL80 reaches a rule-of-thirds reserve after about 25 minutes and is empty after 39 minutes, counting time at that depth only. Enter your own fill, depth and breathing rate in the gas consumption calculator.

How much does an AL80 weigh?

About 14.3 kg (31.5 lb) empty, the dataset's typical figure without a valve; the valve and maker change it a little. In the water, with its valve, a full AL80 is about 0.8 kg negative and an empty one about 2.0 kg positive, which is why it floats at the end of a dive.

HP100 vs AL80: which holds more gas?

The HP100: a steel cylinder at 3442 psi (237 bar) with a larger water volume. The chart above lists both, with weight and buoyancy. The HP100 ends a dive close to neutral (Faber's sheet gives −0.6 lb at 500 psi), where the AL80 is clearly positive; figures vary by maker, so check your own weighting rather than assuming a figure.

Why is my cylinder named in cubic feet in the US and litres in Europe?

Two traditions. European cylinders are stamped with their water volume and the working pressure, so a 12 L cylinder at 232 bar. US cylinders are sold by the gas they hold at their working pressure. Converting a water volume straight to cubic feet gives a figure under one; the dive unit converter has a table that shows the difference.

Does an aluminium tank float when empty?

Most do. Aluminium is light for its volume, so once the gas is gone a typical aluminium cylinder is positively buoyant, while most steel cylinders stay negative. The Full and Empty columns of the chart show each cylinder's figures from the dataset.

Sources

Dive Kit open cylinder dataset (MIT licence) : Water volume, working pressure, empty weight and buoyancy full, at 50 bar and empty for each of the 38 cylinders.
Luxfer aluminum cylinder specifications (XS Scuba sheet, rev. 19A) : The AL80's 77.4 cu ft true capacity, 11.1 L water volume and 3000 psi (207 bar) service pressure; buoyancy quoted in sea water with the valve.
Faber FXG hot-dip galvanized HP cylinder specifications : The HP100's 101.3 cu ft at 3442 psi (237 bar) and its −0.59 lb buoyancy at 500 psi.
NIST Chemistry WebBook, Thermophysical Properties of Fluid Systems : The nitrogen and oxygen density data behind the compressibility factor Z used for the real-gas capacity.

Last updated 30 October 2026 · English page

Scuba Tank Sizes and Cylinder Chart