Types of plastic: the seven resin codes and what each one is used for
The number inside the triangle is a resin identification code, not a recycling promise. What each of the seven codes means and where you find it.
In this article
The number stamped inside the triangle on a plastic container is a resin identification code. It runs from 1 to 7 and tells you which polymer the item is made of.
It is not a recycling symbol. That distinction is the single most useful thing to know about these codes, and it is the one most often misread.
The seven codes
| Code | Abbreviation | Full name |
|---|---|---|
| 01 | PET or PETE | Polyethylene terephthalate |
| 02 | HDPE | High-density polyethylene |
| 03 | PVC | Polyvinyl chloride |
| 04 | LDPE | Low-density polyethylene |
| 05 | PP | Polypropylene |
| 06 | PS | Polystyrene |
| 07 | Other | Everything that does not fit the first six |
Six of those seven identify one specific polymer each. The seventh is a catch-all, and that is where most of the confusion around plastic labelling comes from.
Code by code
01 · PET
The clear, rigid plastic of beverage bottles and food containers. It is the most widely collected code in curbside programs and the one with the most developed recycling market.
02 · HDPE
Opaque and stiffer than PET. Milk jugs, detergent bottles and shampoo containers sit here. Like PET, it has an established recycling stream.
03 · PVC
Used in pipes, cable insulation and some rigid packaging. It is the code that recycling programs are least likely to accept, because PVC contaminates other streams when it slips through.
04 · LDPE
Flexible and thin. Shopping bags, squeeze bottles and film wrap. The material itself is recyclable, but the format is the problem: film jams the machinery in most sorting facilities.
05 · PP
Yogurt containers, bottle caps and many food tubs. It handles heat better than the codes above it, which is why it turns up in microwave-safe packaging.
06 · PS
Polystyrene, in both rigid form and the expanded foam used for cups and protective packing. It is light, bulky and expensive to transport, and that economics is why many programs refuse it.
07 · Other
This is not a material. It is the bin for everything else, including polycarbonate, bioplastics and multi-layer composites.
Two items with a 7 can have nothing in common, which is exactly why the code tells you so little on its own.
What the code does not tell you
Here is the part worth reading twice. These are commonly called plastic recycling codes, but they are resin identification codes: they identify the polymer, not what your local program accepts.
Whether an item gets recycled depends on the facility, the local market for that resin, and how clean and separated the material arrives.
A jurisdiction can have outlets for all seven codes, provided the plastics are separated properly. Another can accept only 1 and 2.
The practical consequence
The number on the bottom is a starting point, not an answer. The answer is on your municipality's website, and it changes as markets change.
The second consequence is for anyone sourcing packaging: specifying "recyclable plastic" means nothing without naming the resin and the destination market.
How to read a container
- Look at the bottom or the back panel. The triangle is usually moulded into the material rather than printed.
- Check every component separately. A bottle can be PET while its cap is PP and its label is PS.
- Do not assume the triangle means recyclable. It is an identification mark that happens to use the same shape.
- Rinse before sorting. Contamination is one of the main reasons otherwise recyclable material is rejected.
Where the codes come from
The system was created to make sorting possible. Before it existed, a sorting line had no reliable way to tell one clear polymer from another once the label was gone.
The 7 numbers give every item a machine-readable and human-readable identity. That is the whole purpose, and it is a narrow one.
Why 6 materials and 1 category
Codes 1 to 6 cover the polymers that dominated consumer packaging when the system was designed. Everything developed since, plus every blend and multi-layer construction, ends up in code 7.
That imbalance grows over time. A system with 6 named materials and 1 open category becomes less informative as the seventh fills up.
What this means for procurement
For anyone specifying packaging rather than sorting it at home, the codes work as a shared vocabulary between buyer, converter and waste handler.
A specification that names the resin removes ambiguity from the brief. One that says "recyclable" leaves the most important variable undefined, because recyclability is a property of the local system rather than of the material.
The practical version: name the code, name the destination market, and confirm that the market accepts that code today rather than in principle.
Frequently asked questions
What are the 7 types of plastic?
PET (1), HDPE (2), PVC (3), LDPE (4), PP (5), PS (6) and a seventh category labelled Other, which covers every polymer outside the first six.
Which plastic number should be avoided?
Code 3, PVC, is the one recycling programs most often reject, and code 6, PS, is frequently refused for economic reasons. Code 7 is impossible to assess as a group, because it is a category rather than a material.
Is number 7 plastic toxic?
The number alone cannot answer that. Code 7 includes polycarbonate, bioplastics and composites, with very different properties. The material has to be identified specifically before any assessment is possible.
Are the codes the same everywhere?
The numbering system from 1 to 7 is used internationally to aid identification. What differs by country and by municipality is which of those codes gets collected and processed.
Why is my bottle PET but its cap is not?
Because each component is engineered for a different job. The bottle needs clarity and rigidity; the cap needs to seal repeatedly without cracking. That is why caps are commonly PP, code 5.
Do the codes indicate food safety?
No. They identify the polymer family. Food-contact suitability is governed by separate regulation and depends on additives, processing and intended use, none of which the resin code captures.
Can I tell the code without the symbol?
Not reliably. Some materials have recognisable behaviour, such as the crinkle of certain films or the rigidity of PET, but those signals are not dependable enough for sorting. When the code is missing or unreadable, the safe assumption is that the item cannot be identified.
What happens to code 7 in a sorting facility?
In most cases it is separated out and sent to disposal, because a mixed category has no single downstream buyer. That is the practical cost of a catch-all: it groups together materials that would each need a different process.
The one number to remember from all of this is 7, and what it means: not a plastic, but the absence of a classification.
