Key takeaways
- A standard 25kg woven PP bag programme loads roughly 24-25 tonnes into a 20ft container — typically around 1,000 bags on circa 20 pallets — and is the default for resellers, compounders and small-lot buyers who need to break the lot down.
- FIBC bulk bags (commonly Type C grounded or Type D anti-static, 1,000-1,250kg net) cut handling to one forklift lift per tonne but carry a payload penalty: a typical FIBC load lands near 18-21 tonnes in a 20ft box versus 24-25 tonnes for 25kg bags.
- Octabins (octagonal cartons on a pallet base, usually 700-1,250kg net) suit free-flowing pellet and automated decanting, but the corrugated structure and pallet eat into payload and they are sensitive to moisture and crush damage in humid transit.
- Bulk/silo delivery in liner-bag containers gives the lowest cost per tonne and the cleanest pellet, but works for only one grade per movement and demands silo infrastructure and tight moisture control — it is a high-volume converter format, not a trader's.
The packaging line in a polymer contract reads like an afterthought — "25kg PP woven bags on pallets" or "1,000kg FIBC" — but it quietly sets three numbers that matter: how many tonnes you fit in a box, how much labour you burn unloading them, and how exposed the pellet is to moisture, dust and crush damage in transit. Get the format wrong and you either ship air, pay your warehouse to lift one sack at a time, or open a container to find caked resin and torn liners.
Four formats dominate the trade: 25kg bags (the universal small unit), FIBC or bulk bags (the one-tonne workhorse), octabins (palletised cartons for free-flowing pellet), and bulk/silo (no packaging at all). Each suits a different buyer. The right call depends on your downstream process, your handling equipment and the moisture sensitivity of the grade — not on which looks cheapest on the invoice. This pairs directly with how the container itself is loaded and secured.
Start with the headline trade-off: payload versus handling. The smaller the unit, the more tonnes you cram into a container — but the more individual lifts your team makes at the other end. The figures below are indicative planning ranges for a 20ft container of standard-density polyolefin; exact loads vary with bulk density (LDPE differs from HDPE), pallet pattern, and whether the box is payload- or volume-limited.
| Format | Typical net unit | Payload per 20ft | Handling | Best for |
|---|---|---|---|---|
| 25kg bags (woven PP, palletised) | 25 kg | ~24-25 MT (~1,000 bags) | Manual or pallet; many lifts | Resellers, compounders, small lots, multi-grade buyers |
| FIBC / bulk bag | 1,000-1,250 kg | ~18-21 MT | One forklift lift per bag | Automated lines, large continuous runs |
| Octabin | 700-1,250 kg | ~18-21 MT | Forklift; clean auto-decant | Free-flowing pellet, automated dosing |
| Bulk / silo (liner-bag) | Loose pellet | ~21-24 MT | Pneumatic / gravity to silo | High-volume single-grade converters |
Notice that 25kg bags win decisively on payload — often 4-6 tonnes more per 20ft box than FIBC or octabins. Across a full programme that gap compounds into real freight savings, which is why most woven PP raffia bag programmes still dominate trader and reseller flows. The catch is at the receiving dock.
A 24-tonne load of 25kg bags is roughly 960-1,000 individual sacks. If your team breaks them by hand — common for compounders dosing multiple grades — that is a lot of bending, and the labour cost per tonne handled can dwarf the few dollars per tonne saved on freight. Palletised and shrink-wrapped bags help, but you still eventually open every sack.
FIBC flips the maths. One forklift lift moves a tonne. A bag with a discharge spout feeds straight into a hopper or blender, and a continuous line can run for hours per bag. For a converter running steady volume on one or two grades, FIBC slashes handling labour and dust exposure — even though each container carries fewer tonnes. Octabins offer similar single-lift handling with a more stable, stackable footprint, and their rigid walls suit automated, repeatable decanting better than a floppy bulk bag.
The cheapest packaging on the invoice is rarely the cheapest packaging in your plant — handling labour and contamination losses settle the real account.
FIBC are not interchangeable. The A/B/C/D classification governs how the bag handles static charge generated as pellets flow — a genuine ignition risk where dust or flammable vapours are present. Specifying the wrong type is a safety failure, not a preference.
- Type A — plain woven PP, no static protection. Only for non-flammable products in non-hazardous areas.
- Type B — low breakdown-voltage fabric that prevents propagating brush discharges, but is not earthed and does not dissipate charge.
- Type C — conductive (often with interwoven conductive threads); must be electrically grounded during fill and discharge. The common choice around flammable atmospheres.
- Type D — anti-static / static-dissipative; safely dissipates charge without an earth connection, useful where reliable grounding cannot be guaranteed.
For most resin handling near dust or solvent vapour, buyers specify Type C (with a documented grounding procedure) or Type D. Also confirm the safe working load and the safety factor — under ISO 21898, 5:1 is standard for single-trip bags and 6:1 for multi-trip — plus UV stabilisation if bags will sit in the yard, and a food-grade inner liner where the resin demands it.
Every transfer is a chance to introduce contamination, and every hour of exposure is moisture pickup. Hygroscopic and surface-sensitive grades degrade in process when wet — splay, voids and chain scission in nylons and PET. The packaging choice is really a liner-integrity choice.
| Format | Moisture risk | Contamination path | Mitigation |
|---|---|---|---|
| 25kg bags | Low if sealed; high if torn | Punctures, repeated handling | Intact liner, palletise, shrink-wrap |
| FIBC | Low-moderate | Spout seals, liner pinholes | Spec inner liner, check seams |
| Octabin | Moderate-high in humid lanes | Corrugated dust, crush, wicking | Liner + moisture barrier, avoid floor stowage |
| Bulk / silo | Lowest with fresh liner | Residue from prior cargo | Food-grade single-use liner, dry-air conveying |
Bulk/silo gives the cleanest pellet because the resin is never exposed to ambient air — but only with a fresh, correctly specified liner and dry conveying. Among packaged formats, sealed bags and lined FIBC perform well; octabins are the most exposed in humid deep-sea lanes because corrugated board wicks moisture and crushes under load. Whatever the format, verify liner spec, seal integrity and bag condition at pre-shipment inspection — and read the moisture status off the certificate of analysis before the box ships.
- Trader / reseller — 25kg bags. Maximum payload, easy to split lots across grades and customers, and the format the next buyer expects.
- Compounder / small-batch processor — 25kg bags, accepting the handling labour for flexibility across many grades and recipes.
- Mid-size converter on steady grades — FIBC. Fewer lifts, lower dust exposure, clean hopper feed; the payload penalty is worth it.
- Automated dosing / free-flowing pellet — octabins. Stable, stackable, clean auto-decant — but keep them out of humid floor stowage.
- High-volume single-grade plant with silos — bulk/silo. Lowest cost per tonne and cleanest pellet, provided you have the infrastructure and one grade per movement.
Set the packaging line on the RFQ deliberately, not by habit. Quote the format that fits your unloading dock and your process, confirm FIBC type, safety factor and liner spec in writing, and check payload assumptions against the actual container plan before you fix freight. When the format matches the buyer, the cheapest invoice and the cheapest plant finally agree — talk to the OmniaStrata desk or review our polyethylene programmes to spec it correctly from the first order.
Frequently asked
Questions on the desk
How many tonnes of polymer fit in a 20ft container for each packaging type?
For 25kg woven PP bags on pallets, a 20ft container typically carries around 24-25 tonnes (about 1,000 bags). FIBC bulk bags usually land near 18-21 tonnes because the bags and any pallets consume payload and cube. Octabins fall in a similar 18-21 tonne band. Bulk liner-bag (silo) loading can reach roughly 21-24 tonnes with no packaging weight, constrained by the container's payload limit rather than its volume. These are indicative planning figures and vary with bulk density and stow pattern.
What is the difference between FIBC Type A, B, C and D bags?
The types describe electrostatic behaviour. Type A offers no static protection and suits non-flammable, non-dusty products. Type B prevents propagating brush discharges but is not earthed and does not dissipate charge. Type C is conductive and must be grounded during fill and discharge. Type D is anti-static and dissipates charge safely without an earth connection. For resin handling around flammable atmospheres or dust, buyers specify Type C (grounded) or Type D.
Which packaging format gives the lowest contamination risk for polymer pellets?
Bulk/silo delivery with a fresh, food-grade liner generally gives the cleanest pellet because the resin is not exposed to ambient air, dust or repeated transfers. Among packaged formats, sealed 25kg bags and lined FIBC perform well when the inner liner is intact. Octabins and unlined bags carry higher risk from corrugated dust, moisture pickup and damage in humid transit. Always confirm liner specification and seal integrity at pre-shipment inspection.
Should I buy polymer in 25kg bags or FIBC bulk bags?
Choose 25kg bags if you resell, compound in small batches, or need to break the lot into multiple grades and customers — they maximise payload per container and are easy to handle manually. Choose FIBC if you run automated dosing or large continuous lines, value fewer lifts and lower per-tonne handling labour, and can accept a lower payload per container. The decision is a trade-off between cost per tonne shipped and cost per tonne handled in your plant.
Are octabins reusable, and are they worth the premium?
Some octabins are designed for multiple trips, but in deep-sea export trade most are treated as single-use because return logistics rarely make economic sense across continents. They earn the premium when your line decants free-flowing pellet automatically and you want a stable, stackable carton without the floppiness of an FIBC. For manual break-bulk or moisture-sensitive resins in humid lanes, they are usually not the best choice.
General market commentary from the OmniaStrata desk, provided for information only. It is not legal, financial, tax, or trading advice, and it is not an offer or a commitment to any terms. Figures such as price ranges, spreads, financing costs, and credit periods are illustrative market context, not OmniaStrata's rates or terms. Actual contract terms — including price, payment instrument, credit, insurance, and Incoterms — are agreed in writing on a per-transaction basis and at OmniaStrata's discretion. Market conditions change; figures reflect the publication date.