A UN number lookup sounds like it should take ten seconds. Type in a product, get four digits back. In practice most people either cannot find their product at all, or find three plausible entries and no way to choose between them.
This is a reference you can keep. It explains what the number actually identifies, how to search properly, and lists the codes that e-commerce and parcel shippers hit most often — with the traps attached to each.
What a UN number identifies
A UN number is a four-digit identifier assigned by the UN Sub-Committee of Experts on the Transport of Dangerous Goods. It identifies a substance or article, not a level of danger. UN1090 is acetone. UN1845 is dry ice. UN3480 is a lithium-ion battery travelling on its own.
That distinction matters because people routinely try to look up a hazard when they should be looking up a material. "Flammable liquid" is a class, and Class 3 contains hundreds of UN numbers. You need the specific one, because everything downstream depends on it:
- The proper shipping name that goes on the paperwork
- The hazard class and division that decides the label
- The packing group that sets the packaging performance standard
- The special provisions and quantity limits per mode
- Whether your carrier accepts it at all, and by which service
How to run a UN number lookup properly
The authoritative list is the Hazardous Materials Table at 49 CFR 172.101, free on eCFR. It is complete and correct. It is also alphabetised by chemical name, which is unhelpful when what you have in front of you is a bottle labelled "Ultra Grip Adhesive".
Three steps make it tractable:
1. Get the chemical identity, not the brand name
Section 3 of the safety data sheet gives you composition. Section 14 gives you the supplier's own transport classification, which is a useful starting point but should be verified rather than trusted — it is often written for a bulk drum, not your retail size, and it goes stale.
2. Search for the specific entry first
If your material is ethanol, you want UN1170, not a generic flammable liquid entry. A specific entry always takes precedence. Only when nothing specific describes the material do you fall back to an n.o.s. entry.
3. Check the concentration and the configuration
This is where most lookups go wrong. The same substance can land on different entries depending on strength, physical state or how it is packed. Corrosive entries in particular are concentration-dependent — a dilute solution may not be regulated at all.
The UN numbers e-commerce shippers meet most
| UN | Proper shipping name | Class | PG | Typical products |
|---|---|---|---|---|
| UN1090 | Acetone | 3 | II | Nail varnish remover, solvents |
| UN1170 | Ethanol solution | 3 | II | Hand sanitiser, tinctures |
| UN1219 | Isopropanol | 3 | II | Cleaning wipes, diffuser bases |
| UN1263 | Paint / paint related material | 3 | II or III | Nail varnish, touch-up paint |
| UN1266 | Perfumery products | 3 | II or III | Fragrance, aftershave |
| UN1760 | Corrosive liquid n.o.s. | 8 | I–III | Descalers, speciality cleaners |
| UN1791 | Hypochlorite solution | 8 | II or III | Bleach, pool sanitiser |
| UN1824 | Sodium hydroxide solution | 8 | II or III | Drain cleaner, soap making |
| UN1845 | Carbon dioxide, solid | 9 | — | Dry ice in cold-chain parcels |
| UN1950 | Aerosols | 2.1 / 2.2 | — | Deodorant, dry shampoo, sprays |
| UN1993 | Flammable liquid n.o.s. | 3 | I–III | Mixtures with no specific entry |
| UN3077 | Environmentally hazardous solid n.o.s. | 9 | III | Some detergents, pesticides |
| UN3082 | Environmentally hazardous liquid n.o.s. | 9 | III | Marine-hazard formulations |
| UN3090 | Lithium metal batteries | 9 | — | Coin cells shipped alone |
| UN3091 | Lithium metal batteries in / with equipment | 9 | — | Key fobs, watches, sensors |
| UN3480 | Lithium ion batteries | 9 | — | Power banks, spare packs |
| UN3481 | Lithium ion batteries in / with equipment | 9 | — | Phones, speakers, laptops |
| UN3082 | Environmentally hazardous liquid | 9 | III | Concentrated cleaners |
| UN1133 | Adhesives | 3 | I–III | Solvent-based glues |
| UN1325 | Flammable solid, organic, n.o.s. | 4.1 | II or III | Some fire-lighting products |
When one product has two UN numbers
Consider a brand shipping wireless earbuds. The earbuds contain lithium cells, so the classification is UN3481, contained in equipment. Then they add a spare charging case as a standalone accessory. That case ships on its own, so it is UN3480.
Same chemistry. Same supplier. Two UN numbers, two packing instructions, and, critically, two different carrier positions, because UN3480 is cargo aircraft only. The variable is not the battery; it is how it travels. Our guide to PI965, PI966 and PI967 works through that split in detail.
A UN number lookup that returns a number without the proper shipping name and packing group beside it has not finished the job. Those fields travel together on the shipping paper, and a mismatch between them is what a carrier's screening actually catches.
Classify7 ruleset team
Five ways a UN number lookup goes wrong
Having watched a lot of these, the failures cluster into a short list.
Searching the hazard instead of the material
"Corrosive" is a class containing hundreds of entries. A UN number lookup needs a substance, not a symptom. Start from section 3 of the SDS.
Taking the first plausible hit
The table is alphabetical, so near-matches sit next to each other. "Alcohols, n.o.s." and "Alcoholic beverages" are different entries with different consequences, and one is a lot easier to reach for than the other.
Ignoring physical state
Many substances have separate solid and liquid entries, and a solution entry distinct from both. Sodium hydroxide is a clear example: the solid and the solution do not share a UN number.
Missing a subsidiary risk
A UN number lookup that returns a primary class and stops has not finished. Materials that are both flammable and corrosive carry two labels, and the second one is the one that gets left off.
Not recording where the answer came from
Six months later, nobody remembers whether a number was derived from the table, copied from a supplier, or guessed. The UN Model Regulations published by UNECE are the upstream source for the whole system, and citing what you used costs nothing at the time and everything later.
Using n.o.s. entries without getting it wrong
The n.o.s. entries (UN1993 flammable liquid, UN1760 corrosive liquid, UN3082 environmentally hazardous liquid) exist because no table can list every mixture ever formulated. They are legitimate and often necessary.
Two rules govern them. First, use one only when no specific entry describes your material. Second, you must add the hazardous constituents in brackets after the shipping name: UN1993, Flammable liquid, n.o.s. (contains ethanol, isopropanol), 3, II. Leaving the brackets empty is one of the most common documentation defects in parcel hazmat.
- Copying a UN number off a competitor's listing. Their formulation is not yours.
- Reaching for UN1993 first because it is easy to find. Specific entries take precedence.
- Ignoring concentration on Class 8 entries, where dilution can change or remove the classification.
- Taking section 14 of an old SDS as gospel without checking the edition it was written against.
- Recording the UN number but not the packing group, then guessing it later.
Running a UN number lookup in bulk
If you are validating a catalogue rather than a single product, a manual UN number lookup per SKU does not scale. Send the description or composition to POST /api/classify and the number comes back with the proper shipping name, class, packing group and carrier eligibility attached — plus the provision each field came from, so the answer is auditable rather than merely confident.
Where the ruleset cannot reach a defensible answer, it returns needs_review rather than a nearest guess. For the broader decision of whether a product is in scope at all, start with how to tell if your product is a dangerous good, and browse the hazard class reference when you want to see what else sits in the same class.
