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A FIBC bulk bag specification sheet is more than a list of dimensions and materials. It is the technical agreement that connects the product being packed, the customer’s handling process, the bag design, and the manufacturer’s production requirements.
Two bulk bags may look nearly identical but perform very differently. A change in fabric weight, lifting-loop length, liner construction, seam design, or discharge-spout size can affect filling efficiency, containment, handling safety, and total packaging cost. This is why buyers should compare complete FIBC bulk bag specifications rather than relying on a product photo, a general description, or unit price alone.
If you are still defining the basic container and its available configurations, begin with this overview of FIBC bags. This guide focuses specifically on how to read, verify, and approve a specification sheet before placing an order.
An FIBC specification sheet records the technical details required to manufacture and inspect a particular bag design. Depending on the supplier, it may be presented as a table, technical drawing, product data sheet, or a combination of these documents.
A complete specification should answer four basic questions:
What product will the bag contain?
How will the bag be filled, lifted, stored, transported, and discharged?
Which components and materials will be used?
What requirements will be used to approve the finished bag?
The document should identify a specific design rather than describe a general product category. Terms such as “standard one-ton bulk bag” are not sufficient because bags with the same nominal capacity can have different dimensions, construction styles, fabric weights, loop configurations, liners, closures, and safety ratings.
The final approved specification should also carry a product code, revision number, and approval date. This prevents an outdated drawing or quotation from being used for a later production order.
Buyers often begin by choosing a familiar bag size. A better approach is to define the product and operating conditions first, because these factors determine most of the bag specifications that follow.
Important product information includes:
Product name and physical form
Loose and settled bulk density
Target net fill weight
Particle size and flow characteristics
Moisture or oxygen sensitivity
Abrasiveness
Filling temperature
Food-contact or hygiene requirements
Hazardous-goods status
Potential electrostatic risks
Required level of dust or product containment
Bulk density is especially important because it connects the required fill weight with the volume of the bag. Buyers should use representative product data rather than an approximate density copied from a general reference. Aerated powder, settled powder, damp material, and compacted material can have different densities.
The basic relationship is:
Required product volume = Target fill weight ÷ Bulk density
For example, a buyer filling 1,000 kg of material with a bulk density of 650 kg/m³ requires approximately 1.54 m³ of product volume.
However, 1.54 m³ should not automatically become the nominal bag volume. The final dimensions must also account for filling behavior, available headspace, bag shape after filling, pallet size, filling equipment, and container-loading restrictions. A more detailed discussion of how bulk density affects FIBC selection can help buyers establish a reliable starting point.
The following checklist covers the main sections buyers should expect to see.
Specification field | What it describes | What the buyer should verify |
|---|---|---|
Product and application | Material being packed and operating environment | Product characteristics reflect actual production conditions |
Net fill weight | Intended weight of product in each bag | Consistent with filling equipment, logistics plan, and SWL |
Bulk density | Product weight per unit of volume | Based on representative loose or settled density |
Bag dimensions | Width, length, height, and component dimensions | Units, tolerances, and measurement method are clear |
Bag construction | U-panel, circular, four-panel, baffle, or another structure | Suitable for stability, space use, and handling requirements |
SWL | Safe Working Load assigned to the bag | Equal to the approved payload and clearly marked |
Safety factor | Design and test relationship associated with the bag | Not confused with additional allowable payload |
Electrostatic type | Type A, B, C, or D classification where applicable | Selected according to product and operating atmosphere |
Body fabric | Material, color, GSM, and other fabric details | GSM refers to the correct component and condition |
Coating or lamination | Film applied to woven fabric | Required barrier and airflow performance are defined |
Inner liner | Liner material, thickness, shape, and attachment | Compatible with the product, bag, and filling process |
Filling design | Open top, duffle top, or filling spout | Dimensions match the filling equipment |
Discharge design | Plain bottom, discharge spout, or another closure | Supports the required discharge rate and control |
Lifting loops | Style, width, length, position, and color | Compatible with forklifts, cranes, or filling frames |
Seams | Stitching and sift-proofing requirements | Appropriate for the product’s particle size and leakage risk |
Printing and labels | Artwork, handling marks, traceability, and warnings | Text, colors, position, and regulatory markings are approved |
Document pouch | Size, material, closure, and position | Suitable for shipping documents or batch information |
Testing and documentation | Applicable tests, reports, declarations, or certificates | Documents apply to the specified bag design |
Packing method | Bale quantity, pallet type, wrapping, and container quantity | Suitable for storage, transport, and warehouse handling |
A specification is complete only when these fields agree with one another. A technically detailed sheet can still be wrong if the dimensions, payload, openings, and operating process do not match.
FIBC dimensions are generally expressed as width × length × height for rectangular designs or diameter × height for circular designs. Buyers should confirm whether the dimensions refer to an empty bag, a flat measurement, or an expected filled profile.
The specification should identify:
Bag body width or diameter
Bag body length, where applicable
Body height
Filling-spout dimensions
Discharge-spout dimensions
Lifting-loop free height
Dimensional tolerances
Measurement units
Any special pallet or container restrictions
Theoretical volume alone does not predict the exact filled shape. Woven polypropylene fabric deforms under load, and a standard bag may bulge after filling. A baffle design can help retain a more rectangular profile, but it also changes the internal construction and usable volume.
Buyers should therefore assess dimensions against the complete handling system. The bag must fit under the filling head, on the selected pallet, through warehouse access points, and inside the intended truck or shipping container. Existing guidance on common FIBC bulk bag sizes provides additional context, but the final dimensions should always be based on the actual product and equipment.
The Safe Working Load is the maximum approved product weight for the specified bag under its intended conditions of use. It should be stated clearly in kilograms or pounds.
The safety factor is a design and testing relationship. It does not mean the buyer may load the bag above its stated SWL. For example, a bag marked with an SWL of 1,000 kg must not be filled to a higher weight simply because its specification lists a safety factor.
A buyer should confirm that the sheet states:
SWL
Safety factor
Intended service category
Applicable design or test basis
Required handling and warning marks
Whether a bag is intended for single-trip use or an approved multiple-trip application should be stated directly. It should not be inferred from one number without supporting design, test, inspection, and use information.
This section of a general specification sheet should record the approved values. The detailed meaning of 5:1, 6:1, test loads, and service conditions requires a separate technical review.
Bag construction describes how the body panels are assembled. Common options include:
U-panel
Circular or tubular
Four-panel
Baffle or Q-bag
Single- or two-loop construction
This field affects filled shape, stability, seam placement, production cost, and space utilization. It should not be confused with the Type A, B, C, or D classification.
Type A through Type D refers primarily to electrostatic behavior and suitability for particular products and operating atmospheres. It is not a ranking of mechanical strength. A Type C or Type D bag is not automatically stronger than a Type A bag, and bulk density alone does not determine the required electrostatic type.
Where electrostatic control matters, the specification should clearly identify the bag type, compatible liner requirements, marking, and any operational requirements such as grounding. These details should be reviewed against the actual product and the filling or discharge environment.
GSM means grams per square meter and is commonly used to describe the basis weight of the woven polypropylene fabric. It can influence material usage and performance, but a higher GSM does not automatically guarantee a better bag.
Overall performance also depends on:
Polypropylene resin and additives
Tape quality
Weaving density
Fabric tensile properties
Body construction
Loop design
Seam strength
Coating
Manufacturing consistency
The specification should state which fabric component the GSM refers to. Body fabric, top fabric, bottom fabric, baffles, and lifting loops may use different materials or weights. Buyers should also determine whether the stated value includes the coating or applies only to the uncoated woven fabric.
Uncoated woven fabric allows more airflow and may be suitable for products that do not require a strong moisture or dust barrier. Coated or laminated fabric adds a film layer that can improve resistance to moisture and reduce the movement of fine particles through the weave.
A coating alone should not be interpreted as a guarantee that the complete bag is waterproof or completely dust-tight. Seams, closures, needle holes, and handling conditions also affect containment.
An inner liner provides an additional barrier between the product and the woven bag. A liner specification may include:
Material
Thickness in microns or mils
Lay-flat, gusseted, form-fit, or baffle construction
Loose, tabbed, glued, or sewn attachment
Filling and discharge openings
Barrier or antistatic properties
Food-contact requirements
Sealing method
Simply writing “PE liner included” leaves too much room for interpretation. Liner shape, thickness, dimensions, attachment, and compatibility with the filling process should all be defined. Buyers handling sensitive or fine materials can review the available FIBC liner options before approving this part of the sheet.
The top and bottom design should match the customer’s equipment and the flow behavior of the product.
Common filling options include:
Open top
Duffle top
Filling spout
Conical top
Top flap or cover
Common discharge options include:
Plain bottom
Standard discharge spout
Conical discharge spout
Spout with flap
Star or petal closure
Iris closure
Full-bottom opening
For every spout, the specification should include diameter or width, length, closure method, tie material, and any flap or cover. It should also state whether the dimensions are measured flat or as a finished opening.
A filling spout that is too narrow may slow production or prevent proper connection to the filling head. A spout that is too short may be difficult to secure. At discharge, the wrong design can cause uncontrolled flow, dust release, product bridging, or excessive residue inside the bag.
The specification should describe the physical configuration. Flow-rate calculations and detailed discharge-system selection belong in a separate process review.
Lifting loops connect the bag to forklifts, cranes, filling frames, and other handling equipment. Their configuration should be selected according to how the bag will actually be moved.
The sheet should identify:
Number of loops
Loop style
Webbing material
Webbing width
Free loop height
Loop position
Loop color
Sewing pattern or attachment area
Any stevedore straps or tunnel loops
Common arrangements include four corner loops, cross-corner loops, side-seam loops, sleeve loops, and single- or two-loop designs.
Loop length is particularly important. Short loops may be difficult for forklift operators to engage, while unnecessarily long loops can reduce control or affect the filling setup. The buyer should verify fork spacing, lifting method, available headroom, and whether the bag must be handled by one operator.
Loop color may support product identification, but color alone does not establish the SWL or technical performance of the bag.
Fine powders can escape through woven fabric, stitching lines, or closure points. When product loss or dust control is a concern, the specification should state the required seam treatment rather than using a general phrase such as “dust-proof bag.”
Relevant fields may include:
Stitch type
Single, double, or triple sift-proofing
Filler cord or felt
Overlock or chain stitching
Seam location
Thread material and color
Coated fabric or liner combination
Closure treatment
The appropriate design depends on particle size, product value, dust-control requirements, filling pressure, and transport conditions. Sift-proof seams can reduce powder leakage, but they do not automatically make the entire package airtight or waterproof.
Printing is not only a branding detail. It can communicate handling instructions, product identification, safety information, batch details, and approved loading conditions.
The specification should define:
Artwork version
Number of print colors
Print sides
Print area and position
Ink requirements
SWL and safety-factor marking
Product or customer code
Manufacturer identification
Batch or traceability information
Handling warnings
Label and document-pouch requirements
The buyer should approve the final artwork separately from the bag drawing. This reduces the risk of producing a technically correct bag with outdated branding, incorrect handling marks, or missing product information.
A specification sheet should state which tests and documents apply to the bag. The exact requirements depend on whether the product is non-dangerous, hazardous, food-contact, or subject to other market-specific rules.
Possible documentation includes:
Approved technical drawing
Product data sheet
Type-test report or test summary
Material declaration
Food-contact declaration, where required
Certificate linked to the specified bag design
Raw-material or batch records
Inspection criteria
Sample approval record
Finished-product marking requirements
General statements such as “ISO standard,” “food grade,” or “UN certified” should be clarified. The buyer should know which standard, test, certificate, product code, and production scope the claim applies to.
Testing methods themselves should be evaluated in a dedicated quality-testing review. On the specification sheet, the priority is to identify the required performance basis and the documents that must accompany approval or shipment.
The empty bags still need to be stored, counted, transported, and introduced into the customer’s production area. Packing details therefore belong on the specification sheet.
Typical fields include:
Number of bags per bale
Number of bales per pallet
Pallet material and dimensions
Inner and outer wrapping
Compression method
Labels on bales or pallets
Estimated quantity per container
Special hygiene or contamination controls
Container quantity should be based on the approved folded bag and final packing method. Liners, longer lifting loops, reinforced components, and special closures can change the packed volume even when the body dimensions remain unchanged.
For food, pharmaceutical, or clean manufacturing environments, the buyer may also need individual packaging, controlled pallet materials, or restrictions on staples and exposed wood.
A practical review can be completed in six passes.
Check that the product, bulk density, fill weight, operating environment, and containment requirements are correct.
Confirm that the target fill weight, product density, bag volume, dimensions, and SWL agree. Do not approve these fields independently.
Compare filling-spout, discharge-spout, loop, and bag dimensions with the actual filling head, discharge station, forklift, pallet, and warehouse restrictions.
Verify the electrostatic type, fabric, coating, liner, seams, closures, SWL, safety factor, and required handling marks.
Confirm the drawing revision, artwork, certificates, test references, labels, document pouch, and traceability requirements.
For a new or materially changed design, evaluate a sample with the actual product and equipment whenever practical. Record any approved changes on the drawing and specification before bulk production.
Buyers should pause the approval process when they find any of the following:
The product is described only as “powder” or “granules.”
Bulk density is missing or based on an unverified estimate.
Dimensions are listed without units or tolerances.
Nominal volume is treated as guaranteed usable fill volume.
SWL is shown without the safety factor or intended service condition.
GSM is listed without identifying the fabric component or coating status.
The electrostatic type is selected according to load weight rather than ignition risk.
The liner is described without material, thickness, shape, or attachment.
Spouts are shown without dimensions and closure details.
“Sift-proof” is stated without a defined seam construction.
A certification claim is not tied to the bag design or supporting document.
Printing artwork and technical drawings carry different revision dates.
Packing quantity is estimated before the final bag configuration is approved.
A cheaper quotation omits components included in the comparison specification.
These omissions do not always mean the bag is unsuitable. They do mean the buyer lacks enough information to compare suppliers or control production consistently.
Before approving an FIBC bulk bag specification sheet, confirm that:
The product and application are clearly identified.
Representative bulk-density data has been used.
Target fill weight and required product volume agree.
Bag dimensions fit the filling, storage, and transport system.
SWL and safety factor are stated separately.
Intended service conditions are documented.
Bag construction and electrostatic type are not confused.
Fabric GSM and coating status are clearly defined.
Liner material, thickness, shape, and attachment are specified.
Filling and discharge openings match the equipment.
Lifting loops match the intended handling method.
Seam and sift-proofing requirements match the product.
Printing, labels, markings, and document pouches are approved.
Required tests and supporting documents are identified.
Packing and pallet requirements are included.
The sheet has a product code, revision number, and approval date.
All changes have been incorporated before bulk production.
A reliable FIBC bulk bag specification sheet should make the bag reproducible, inspectable, and suitable for the buyer’s real operating conditions. No single field—whether it is GSM, SWL, size, or price—can determine suitability on its own.
The most important task is to confirm that the product data, capacity, dimensions, construction, materials, openings, lifting system, and documentation work together. When these details are recorded in one approved specification, buyers can compare quotations more fairly, reduce production misunderstandings, and maintain consistency across repeat orders.
There is no single field that determines whether a bag is suitable. Product bulk density, fill weight, dimensions, SWL, construction, fabric, openings, and handling requirements must be reviewed together.
No. Higher GSM indicates more material per unit area, but it does not by itself guarantee better performance. Resin quality, weaving, construction, lifting loops, seams, coating, and manufacturing consistency also affect the finished bag.
No. SWL is the approved payload of the bag. The safety factor is a design and testing relationship and does not permit the user to exceed the marked SWL.
No. Coating or lamination is applied to the woven fabric, while an inner liner is a separate barrier placed inside the bag. Some applications require one, both, or neither.
Only when the relevant product properties and operating conditions fall within the approved design range. Differences in bulk density, particle size, moisture sensitivity, static risk, or flow behavior may require a revised specification.
