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Oxygen cylinder sizes are named with letters and numbers (M4, M6, M9, D, E, 60A, 125, 200, 300), and the letter does not by itself fix the dimensions. The chart below lists 14 sizes with diameter, length, DOT specification, service pressure and content weight in inches and millimetres, all taken from one supplier catalog. This page is general product information, not medical advice.
Oxygen cylinder size chart
Source: Airgas Healthcare, “High-pressure cylinders for medical gas,” in the Airgas gas cylinders catalog (MCM-552), page 6, checked 2026-10-30. The values are that supplier’s own; other suppliers’ cylinders with the same letter can differ. Sizes run from smallest to largest.
| Size | DOT specification | Service pressure, psig (bar) | Diameter, in (mm) | Length, in (mm) | Content weight, lb (kg) |
|---|---|---|---|---|---|
| M4 | DOT-3AL | 2216 (153) | 3.2 (81.3) | 9.0 (228.6) | 0.3 (0.1) |
| M6 | DOT-3AL | 2216 (153) | 3.2 (81.3) | 11.8 (299.7) | 0.5 (0.2) |
| M9 | DOT-3AL | 2015 (139) | 4.4 (111.8) | 10.9 (276.9) | 0.8 (0.3) |
| D | DOT-3AL | 2015 (139) | 4.1 (104.1) | 16.7 (424.2) | 1.3 (0.6) |
| DA | DOT-3AL | 2015 (139) | 4.4 (111.8) | 16.5 (419.1) | 1.3 (0.6) |
| M22 | DOT-3AL | 2216 (153) | 5.3 (134.6) | 17.0 (431.8) | 1.9 (0.9) |
| E | 3AA2015 | 2015 (139) | 4.1 (104.1) | 25.7 (652.8) | 2.0 (0.9) |
| EA | DOT-3AL | 2015 (139) | 4.4 (111.8) | 25.6 (650.2) | 2.0 (0.9) |
| 60A | DOT-3AL | 2216 (153) | 7.3 (184.2) | 23.0 (584.2) | 5.0 (2.3) |
| 125 | 3AA2015 | 2015 (139) | 7.0 (177.8) | 43.0 (1092.2) | 10.5 (4.8) |
| 150A | DOT-3AL | 2015 (139) | 7.3 (185.4) | 46.5 (1181.1) | 13.0 (5.9) |
| 200 | 3AA2015 | 2215 (153) | 9.0 (228.6) | 51.0 (1295.4) | 20.5 (9.3) |
| 250 | 3AA2265 | 2265 (156) | 9.0 (228.6) | 51.0 (1295.4) | 23.3 (10.5) |
| 300 | 3AA2400 | 2400 (165) | 9.3 (235.0) | 55.0 (1397.0) | 27.9 (12.6) |
Content weight is the catalog’s average weight of the oxygen in a full cylinder, as printed. For size 200 the catalog prints specification 3AA2015 next to a 2215 psig service pressure; the stamp on the cylinder itself is the authority.
How to read the chart
The DOT specification names the cylinder’s design rules. In this table the 3AA entries are steel and the 3AL entries are aluminum. Service pressure is the catalog’s rated pressure for that cylinder type. Diameter and length are outside dimensions, and they are what matter for carts, holders and storage racks. For what each fitting on the cylinder does, see the oxygen cylinder parts guide.
How to measure and choose
Measure outside diameter and overall length with the valve fitted, and compare both with the table, since two sizes can share a length and differ in diameter. Then check the stamped marks and label on the cylinder: the oxygen cylinder label guide explains what the markings mean. A regulator or yoke must also match the cylinder valve: the supplier lists its M9 oxygen cylinder with a CGA 870 yoke fitting (see CGA fittings and the oxygen regulator guide). Check your product’s labelling and instructions for use before selecting a holder, cart or regulator.
Letters, supplier codes and water capacity
There is no single worldwide size alphabet. Another Airgas appendix, the specialty gas cylinder size comparison chart, shows size E (about 4 x 26 in) cross-referenced to Linde 005, Air Liquide MEDE and Matheson 3L, so one cylinder carries different codes at different suppliers. Linde describes cylinder sizes as normally defined by the water capacity of the package, meaning its internal volume, which is not the same as how much gas it contains at a given fill. Industrial and laboratory sizes (80, 150, 200, 300) are covered in the compressed gas cylinder sizes entry.
Common mix-ups
D versus DA, E versus EA
In the chart, D and DA share a content weight and almost the same length (16.7 and 16.5 in), but D is 4.1 in across and DA 4.4 in. E and EA match the same way (4.1 and 4.4 in). The A versions are listed as aluminum cylinders. A holder or regulator chosen by the letter alone may not fit.
Size is not fill
Size names the cylinder. How full it is depends on the gauge reading. Do not identify contents by colour alone; see the compressed gas cylinder colour codes guide and read the label.
What are the common sizes of oxygen cylinders?
In this catalog the small portable sizes are M4, M6, M9, D, M22 and E, and the large ones are 125 to 300. The smallest listed, M4, is 3.2 in across and 9.0 in long; the largest, 300, is 9.3 in across and 55.0 in long.
What is the standard size of an oxygen cylinder?
There is no single standard size. In the chart, the portable sizes include D and E, the M-series covers the smallest units, and sizes 200 and 300 are the large cylinders. The right answer depends on the supplier’s catalog and the cylinder’s stamp.
FAQ
Are oxygen cylinder dimensions the same at every supplier?
No. The same letter can differ between suppliers, and the catalog above shows D and DA, and E and EA, differing in diameter even within one supplier.
Where do I find the size of the cylinder I have?
Read the label and the stamped markings on the cylinder, and compare with the supplier’s data sheet. Ask the supplier if they do not agree.
Sources
- Airgas, Gas Cylinders catalog (MCM-552), “High-pressure cylinders for medical gas,” p. 6, https://www.airgas.com/medias/Airgas-Compressed-Gas-Cylinders-MCM-552.pdf, checked 2026-10-30.
- Airgas, Specialty Gas Cylinder Size Comparison Chart, https://www.airgas.com/airgascatalog/catalog/ap004.pdf, checked 2026-10-30.
- Linde, “Broad range of low- and high-pressure cylinders in different sizes,” https://www.linde-gas.com/what-we-offer/supply-modes/cylinders, checked 2026-10-30.
- Airgas, USP Medical Grade Oxygen, Size M9 High Pressure Aluminum Cylinder, CGA 870 Yoke Fitting, product page, https://www.airgas.com/product/Gases/Oxygen/p/OX%20USPM9, checked 2026-10-30.
