ADR packing groups I, II and III
Three Roman numerals for high, medium and low danger: where to find them, which goods go without, and what they mean for packaging and paperwork.
In this guide
Next to many substances in Table A you’ll see a Roman numeral: I, II or III. That’s the packing group. It tells you how dangerous the substance is in transport, and it turns up again in several places: on the transport document, in the code stamped on the packaging and, less directly, in the 1,000 points rule. This guide covers what the three numerals mean and where you’ll meet them on the job.
What the packing groups mean
For packing purposes, substances are assigned to one of three packing groups according to the degree of danger they present (ADR 2.1.1.3):
| Packing group | Danger |
|---|---|
| I | high |
| II | medium |
| III | low |
The lower the numeral, the more dangerous the substance. Part 2 sets the criteria class by class (ADR 3.2.1, explanation of column (4)). For flammable liquids in Class 3 it comes down to the flash-point and the initial boiling point (ADR 2.2.3.1.3). That’s why petrol (UN 1203) is packing group II and diesel (UN 1202) packing group III. Our guide to the ADR classes goes into more detail.
If a flammable liquid also has a subsidiary hazard, a packing group is worked out for that hazard as well. The final class and packing group then come from the table of precedence of hazards in 2.1.3.10 (ADR 2.2.3.1.3).
Goods with no packing group
Packing groups aren’t used for (ADR 2.1.1.3):
- Class 1, explosives,
- Class 2, gases, so aerosols (UN 1950) have none either,
- Class 5.2, organic peroxides,
- Class 6.2, infectious substances,
- Class 7, radioactive material,
- self-reactive substances of Class 4.1.
Articles aren’t assigned to packing groups either, even in classes where substances are. Any performance level their packaging has to meet is set in the relevant packing instruction (ADR 2.1.1.3). Wet batteries filled with acid (UN 2794) in Class 8 are an example: column (4) is blank.
Where to find the packing group
The packing group is in column (4) of Table A in Chapter 3.2 (ADR 2.1.1.3 and 3.2.1). Where one UN number covers more than one packing group, it takes up several consecutive rows (ADR 3.2.1). Ethanol (UN 1170), for instance, appears once in packing group II and once, as a solution, in packing group III. The rows often differ in other columns too, such as the transport category in column (15), so with an entry like that, find the right row first.
On the transport document, the packing group is part of the description of the goods wherever one is assigned. It may be preceded by the letters “PG”, as in “PG II” (ADR 5.4.1.1.1 (d)). Items (a) to (d) and (k) must appear in that order with nothing in between, as in the examples ADR gives:
“UN 1098 ALLYL ALCOHOL, 6.1 (3), I, (C/D)” or “UN 1098, ALLYL ALCOHOL, 6.1 (3), PG I, (C/D)”.
The total quantity is shown separately for each item with a different packing group, even under the same UN number (ADR 5.4.1.1.1 (f)).
X, Y and Z on the packaging
Every packaging has to conform to a design type that has passed the tests in Chapter 6.1 (ADR 4.1.1.3.1). The UN mark therefore includes a letter showing which packing groups the design type was successfully tested for (ADR 6.1.3.1 (c)):
- X: packing groups I, II and III
- Y: packing groups II and III
- Z: packing group III only
So a jerrican marked “Y” has been tested for packing group II and III substances, such as petrol or diesel. It isn’t good enough for a packing group I substance. The rest of the mark, such as the packaging type code, the relative density or maximum gross mass, the test pressure or the letter “S”, and the year of manufacture, is set out in the same sub-section.
Packing groups and the 1,000 points rule
The table in ADR 1.1.3.6.3 lines the transport categories up roughly with the packing groups: category 1 for packing group I, category 2 for packing group II, category 3 for packing group III. The same table has exceptions, though:
- Class 4.2, packing group I: category 0, so no exemption at all.
- Class 6.1, packing group III: category 2. A toxic liquid, organic, n.o.s. (UN 2810) in packing group III is therefore multiplied by 3, not by 1.
- Carbon of animal or vegetable origin (UN 1361), packing group III: category 4.
Goods without a packing group still have a category. Flammable aerosols (group F) go into category 2, and type B organic peroxides into category 1. For the 1,000 points rule the packing group is only a pointer. Always work from the category in column (15) (ADR 1.1.3.6.1).
Easy way to remember it: I high, II medium, III low danger. On the packaging that’s X, Y and Z. For the points, column (15) counts, not column (4).
Practise it now
Packing group questions in the exam usually come bundled with Table A and the transport document. If you can keep column (4) and column (15) apart, you’ll dodge the usual traps.
In the free test you get an explanation and the ADR reference after every answer. The app has more questions on classification, packaging and the transport document.
Sources
ADR 2025: sub-sections 1.1.3.6, 2.1.1.3 and 6.1.3.1, paragraphs 2.2.3.1.3, 4.1.1.3.1 and 5.4.1.1.1, the explanation of columns (4) and (15) in 3.2.1, and Chapter 3.2, Table A. In Great Britain, the Carriage of Dangerous Goods and Use of Transportable Pressure Equipment Regulations 2009 set the legal framework (HSE guidance on ADR and the CDG Regulations). This guide explains the basics. For an actual load, the wording of ADR is what counts.
Updated: 3 October 2026