What is SWL on an FIBC?

SWL (Safe Working Load) is the maximum load the bag is certified to hold in normal use, printed on the bag's label. It is the real payload limit, not the bursting strength.

What is the difference between 5:1 and 6:1 safety factor?

The safety factor is the ratio of burst/proof strength to SWL. A 5:1 bag is single-trip (intended for one journey), a 6:1 bag is multi-trip (designed for repeated use). 6:1 also supports designs qualified for lifting people in some standards.

Can I reuse a 5:1 bulk bag?

A 5:1 bag is a single-trip design and should not be assumed safe for repeated use. Choose 6:1 (multi-trip) when the bag will be emptied, inspected and refilled.

How do I choose the right SWL?

Take your actual filled weight (product + any liner), add margin, then match it to a standard SWL (e.g. 500, 1000, 1200, 1500 kg). Never exceed the printed SWL, and pick 6:1 if the bag will make more than one trip.

FIBC SWL & Safety Factor 5:1 vs 6:1 Explained

SWL is the payload limit; the safety factor is the margin built on top of it. A bag marked SWL 1000 kg, SF 5:1 is certified for 1000 kg in use and was proof-tested to roughly 5× that. 5:1 means single-trip, 6:1 means multi-trip. That is the single most important distinction when you specify a bulk bag.

The two numbers, defined

SWL (Safe Working Load): the maximum mass the bag is designed to hold and lift safely. Printed on the label — treat it as a hard limit.
Safety Factor (SF): the ratio of test/proof strength to SWL. Common values are 5:1 and 6:1; some specialised designs use 8:1.
Single-trip (5:1): built for one fill-and-ship cycle — the economical default for one-way export.
Multi-trip (6:1): engineered for repeated filling, emptying and inspection — lower cost per use over time.

5:1 vs 6:1 at a glance

Attribute	5:1 (single-trip)	6:1 (multi-trip)
Intended use	One journey	Repeated use
Typical fabric	Standard PP weave	Heavier / reinforced weave
Cost per bag	Lower	Higher
Cost per use	Higher (discarded)	Lower (reused)
Best for	Export, one-way flow	Closed-loop, in-plant

How to specify the right rating

Weigh the real load: product + liner + moisture, at maximum fill.
Pick a standard SWL above that figure (500 / 1000 / 1200 / 1500 kg are common; up to 2000–3000 kg on request).
Choose 6:1 if the bag will be emptied, inspected and refilled; choose 5:1 for one-way shipping.
Confirm lifting: 4 loops for crane/forklift, with loop capacity ≥ SWL × 2 for safety.
Label and train: keep the SWL/SF label visible and never overload.

Common misunderstandings

"The bag didn't burst at 3× load, so it is fine" — in-use safety depends on SF, not a one-off overload test.
"We will reuse the cheap 5:1 bag" — 5:1 is single-trip by design; reuse needs 6:1 plus inspection.
"SWL includes the pallet" — SWL is the bag's content load; account for slings and handling separately.

Frequently asked

Do you make 2000 kg or 3000 kg FIBCs?

Yes. ZONGYE produces SWL up to 2000 kg as standard and 3000 kg on engineered request, each with the corresponding test report and label.

What loop capacity should I specify?

Design loops for at least 2× SWL for safe lifting; tell us your handling method (crane hook, forklift, or both) so we size the loops correctly.

Does a liner reduce SWL?

No — the liner sits inside and adds little weight, but a wet or sticky product can, so weigh the filled condition, not the dry one.

Need the right rating for your product?

Share your fill weight, trip count and handling method — we will specify SWL, SF (5:1 or 6:1), loops and fabric.

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FIBC SWL & Safety Factor Explained: 5:1 vs 6:1 Bulk Bags