New TDG Requirements for UN Number Size

New TDG Requirements for UN Number Size

A Small Change with a Big Impact: New UN Number Size Requirements Under TDG

When it comes to dangerous goods regulations, with change comes responsibility. It is up to the shipper to ensure that the correct packaging, labels, markings, placards, and paperwork are used to avoid delays or fines. When changes to the regulations occur, it is of the utmost importance that shippers are aware of them and understand how they may affect their day-to-day operations.

One of the more significant regulatory changes you may have come across recently involves amendments to the TDG Regulations (SOR/2026-112). One change that shippers need to be prepared for involves the size requirements of UN numbers displayed on packaging.

What are the Changes?

As you probably know, when shipping dangerous goods, it is typically a requirement to mark the UN packaging with the correct UN number and proper shipping name of the item you are shipping.  In years past, according to the TDG regulations, for a small means of containment, the UN number just had to be legibly displayed on the packaging on or next to the primary class label. With the new amendment in place, TDG 4.12 (3), now says the following:

For the purposes of paragraph (1)(a), the UN number must be written

(a) for a means of containment with a capacity of 5 L or less or with a net mass of 5 kg or less, in characters that are visible, legible and sized appropriately for the size of the means of containment.

(b) for a cylinder with a capacity of 60 L or less and for any other means of containment with a capacity of 30 L or less but more than 5 L or with a net mass of 30 kg or less but more than 5 kg, in characters at least 6 mm high; or

(c) for all other small means of containment, in characters at least 12 mm high.

This means, depending on the capacity of your packaging, the UN number must now be either a minimum of 6mm or 12mm tall. This requirement is similar to 172.301 (a) (1) in the 49CFR, which also has the 6mm or 12mm minimum size requirements for UN numbers and has been in place for quite some time now. If you are shipping a larger packaging, such as an IBC, there is also a change at 4.15.3 (2) (b) that will affect the size of the UN number marked on them. Here it now says that if the UN number is displayed next to the label, it must be written in black characters and at least 25 MM high on IBCs and other large packaging.

When Do the Changes Go into Effect?

If you currently have hazard class labels with UN numbers that do not meet the new size requirements, you may not need to replace your existing stock immediately.

The transitional provisions in SOR/2026-112 allow shippers to continue following the previous TDG requirements for 12 months after the amendments came into force on June 17, 2026. This transition period ends on June 16, 2027. Beginning June 17, 2027, shippers must comply with the new UN number size requirements.

Don’t wait until the transition period ends. Now is the time to review your existing labels and ensure your UN numbers meet the updated requirements.

ICC offers proper shipping name labels that include UN numbers in a variety of sizes to meet your shipping needs and the new TDG requirements.

Need to update your labels? Explore our Proper Shipping Name Labels or contact ICC to find the right solution for your shipments.

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