Summary. The number in a PEG name is its approximate average molecular weight. PEG 200, 400 and 600 are clear viscous liquids; PEG 2000, 3350, 4000 and 6000 are white waxy solids. All share CAS 25322-68-3 and are soluble in water. Choose by physical form and by the document you need: our technical data sheets cover PEG-400 (IP and USP) and PEG-3350 (USP).
What the PEG number means
Polyethylene glycol (PEG) is a polymer of ethylene oxide. It is sold as a mixture of chains of different lengths, so the number is an average, not an exact size. Our PEG-400 data sheet specifies an average molecular weight of 380.0 to 420.0, and the USP PEG-3350 line gives 3015 to 3685. Because every grade is the same type of polymer, they share one CAS number, 25322-68-3, and the name on the label (PEG 400, polyethylene glycol 400) refers to the size. Macrogol is recorded as an alternative name for polyethylene glycol.
The range at a glance
| PEG number | Form | Approx. melting range (SDS) | Pack formats listed | Data sheet at SPC |
|---|---|---|---|---|
| PEG 200 | Clear viscous liquid | -50 to -30 C | HDPE drums or barrels, IBC | None published |
| PEG 400 | Clear viscous liquid | 4 to 8 C | HDPE drums or barrels, IBC | GLY-008 (IP); GLY-022 (USP) |
| PEG 600 | Clear to slightly yellow liquid; may be semi-solid when cool | 17 to 22 C | HDPE drums or barrels, IBC | None published |
| PEG 2000 | White waxy solid | 50 to 55 C | Confirm on enquiry | None published |
| PEG 3350 | White waxy solid | 53 to 58 C | HDPE bag; woven sack | GLY-022 (USP) |
| PEG 4000 | White waxy solid | 55 to 60 C | HDPE bag; woven sack | None published |
| PEG 6000 | White waxy solid | 58 to 63 C | HDPE bag; woven sack | None published |
Source: SDS section 9 (approximate melting values, one SDS per number); SPC product record; TDS SPC-TDS-GLY-008 and SPC-TDS-GLY-022. The data sheet column shows what we publish. Pack sizes are confirmed on enquiry.
PEG 200 vs PEG 400 vs PEG 600
These three are the liquid numbers. PEG 200 melts at about -50 to -30 C, PEG 400 at about 4 to 8 C and PEG 600 at about 17 to 22 C, which is why the PEG 600 SDS notes it may be semi-solid in cool conditions. If PEG 600 sets in a cold store or an air-conditioned room, refer to the PEG 600 SDS and tell us your storage conditions when you enquire. The SDS approximates relative density at 1.12 to 1.13 g/cm3 at 20 C for the liquid numbers.
General knowledge: as the number rises within the liquid range, viscosity rises. For PEG 400, our SDS approximates 90 to 110 cSt at 20 C, and the data sheet limit is 7.00 to 8.00 cSt at 98.9 C. Always confirm viscosity at the temperature that matters to your process.
PEG 400 vs PEG 4000 vs PEG 6000
This is the liquid-versus-solid question. PEG 400 is a clear liquid you can pump and meter. PEG 4000 and PEG 6000 are white waxy solids that melt at about 55 to 60 C and 58 to 63 C. The SDS describes these as white waxy solids (flakes, pastilles or powder). They are all freely soluble in water. General knowledge: solid PEG is often melted or dissolved in water before use, depending on the process. Molten material can cause thermal burns, so follow the SDS.
PEG 3350 and PEG 2000
PEG 3350 sits in the solid range and is the one solid number for which we hold a data sheet (USP, SPC-TDS-GLY-022): assay 97.0 to 103.0%, moisture 1.0% max, hydroxyl value 30 to 38 mg KOH/g, free ethylene oxide 1 ppm max. PEG 2000 is also a solid; we do not publish a data sheet or a confirmed pack for it here, so ask us.
Liquid or solid? A handling decision walkthrough
- Can your plant pump and meter a viscous liquid? If yes, a liquid number (PEG 200, 400 or 600) avoids a melting or dissolving step. If your line is built for powders or flakes, a solid number fits better.
- Is the storage area cool? PEG 600 can turn semi-solid when cool, so a liquid number with a higher melting range needs more care in a cold store than PEG 200 or PEG 400.
- Do you need to dissolve it? All numbers are soluble in water. General knowledge: solid grades are often dissolved in warm water or melted first; check the dissolution step against the SDS and your process.
- Will you heat it? Molten material can burn, and liquid spills are slippery. Plan the PPE and spill kit before the first drum arrives.
- How will you receive it? Liquids come in drums or barrels and IBCs; solids come in bags and woven sacks. Pack sizes are confirmed on enquiry.
Which grades have documents?
- PEG-400, IP / pharmacopoeial: SPC-TDS-GLY-008.
- PEG-400 and PEG-3350, USP: SPC-TDS-GLY-022.
- Safety data sheets: PEG 200, 400, 600, 2000, 3350, 4000 and 6000.
- A batch Certificate of Analysis is supplied with every delivery.
Technical grade is not food grade or pharma grade, and we do not claim a food-grade or cosmetic-grade PEG. If your product needs a regulated grade, tell us the standard first. See what USP grade means for what those labels mean.
Handling and storage differences
The points below come from the PEG 400 SDS and the product storage record; for the other numbers, refer to each SDS.
- PEG is hygroscopic: keep containers tightly closed in a cool, dry place. Shelf life is 24 months from manufacture.
- Incompatible with strong oxidisers, concentrated acids and halogens.
- Liquid spills are slippery; collect with inert absorbent.
- Molten material can burn.
- PEG 400 is not classified as dangerous goods and the UN number is not regulated, per its SDS.
PEG compared with other glycols
General knowledge: PEG 400 is a polymer, while propylene glycol and glycerine are small single molecules with their own CAS numbers. They are not interchangeable without checking your formulation and regulatory needs.
A simple way to choose
- Decide whether you need a liquid or a solid in your process.
- Pick the number that gives the viscosity or melting behaviour you need.
- Decide whether you need an IP or USP document, and check it exists for that number.
- Choose the pack that suits your handling: drum or IBC for liquids, bag or sack for solids.
- Ask for the batch Certificate of Analysis and compare it with the data sheet.
Getting a quote
Send us the PEG number, grade, quantity, pack and delivery location. We supply from our Redhills warehouse in Chennai and quote within 4 working hours: call or WhatsApp +91 86087 80096, or go to the PEG product page. Supreme Petro Chemicals is a distributor, not a manufacturer.