The Ultimate FIBC Bulk Bag Sizing Reference
Everything you need to know about bulk bag dimensions, capacities, safe working loads, and how to select the perfect size for your specific application. From standard sizes to custom configurations, this guide covers it all.
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Understanding Bulk Bag Dimensions
Learn how FIBC dimensions are specified and what they mean for your application
Width (W)
The measurement across the front face of the bag when laid flat. Standard widths range from 35" to 45". This dimension affects pallet fit and storage footprint.
Depth (D)
The measurement from front to back of the bag. Usually equal to width for square-based bags, but can differ for rectangular configurations.
Height (H)
The vertical measurement from the bottom seam to the top seam. Does NOT include lifting loops or spout lengths. Height determines volume capacity.
Notation Format
Dimensions are written as W x D x H in inches. For example, "35x35x50" means 35 inches wide, 35 inches deep, and 50 inches high.
Standard FIBC Size Chart
Comprehensive list of standard bulk bag sizes with volumes, capacities, and common applications
| Size (WxDxH) | Dimensions | Volume (cu ft) | Typical Capacity | SWL (lbs) | Common Applications |
|---|---|---|---|---|---|
| 35x35x35 | 35" x 35" x 35" | ~24.7 | 1,500 - 2,000 lbs | 2,200 | Lightweight materials, flour, powders |
| 35x35x40 | 35" x 35" x 40" | ~28.2 | 2,000 - 2,500 lbs | 2,500 | Sand, gravel, fertilizer, aggregates |
| 35x35x45 | 35" x 35" x 45" | ~31.8 | 2,200 - 2,700 lbs | 3,000 | Grains, feed, seeds, minerals |
| 35x35x50 | 35" x 35" x 50" | ~35.3 | 2,500 - 3,000 lbs | 3,300 | Grain, seeds, minerals, pellets |
| 35x35x55 | 35" x 35" x 55" | ~38.9 | 2,700 - 3,300 lbs | 3,500 | Light bulk materials, wood chips |
| 35x35x60 | 35" x 35" x 60" | ~42.4 | 3,000 - 3,500 lbs | 3,800 | Agricultural products, recycling |
| 36x36x45 | 36" x 36" x 45" | ~33.8 | 2,400 - 2,900 lbs | 3,000 | Construction materials, sand |
| 36x36x50 | 36" x 36" x 50" | ~37.5 | 2,700 - 3,200 lbs | 3,300 | Agricultural, industrial applications |
| 36x36x60 | 36" x 36" x 60" | ~45.0 | 3,200 - 4,000 lbs | 4,000 | Mixed materials, recycling, aggregates |
| 36x36x65 | 36" x 36" x 65" | ~48.8 | 3,500 - 4,200 lbs | 4,400 | High-volume lightweight materials |
| 37x37x45 | 37" x 37" x 45" | ~35.8 | 2,500 - 3,000 lbs | 3,300 | General industrial, chemicals |
| 37x37x50 | 37" x 37" x 50" | ~39.7 | 2,800 - 3,400 lbs | 3,600 | Minerals, agricultural products |
| 37x37x55 | 37" x 37" x 55" | ~43.7 | 3,000 - 3,500 lbs | 4,000 | Agricultural products, feed |
| 37x37x60 | 37" x 37" x 60" | ~47.6 | 3,400 - 4,000 lbs | 4,400 | Grains, seeds, bulk materials |
| 37x37x70 | 37" x 37" x 70" | ~55.6 | 4,000 - 4,500 lbs | 4,800 | Light density bulk materials |
| 40x40x40 | 40" x 40" x 40" | ~37.0 | 2,500 - 3,200 lbs | 3,500 | Cubic storage, palletized loads |
| 40x40x45 | 40" x 40" x 45" | ~41.7 | 2,900 - 3,600 lbs | 4,000 | Standard industrial applications |
| 40x40x50 | 40" x 40" x 50" | ~46.3 | 3,200 - 4,000 lbs | 4,400 | Mixed industrial, construction |
| 41x41x45 | 41" x 41" x 45" | ~43.8 | 3,000 - 4,000 lbs | 4,400 | Construction materials, sand |
| 41x41x50 | 41" x 41" x 50" | ~48.7 | 3,400 - 4,200 lbs | 4,600 | General purpose, aggregates |
| 41x41x55 | 41" x 41" x 55" | ~53.5 | 3,800 - 4,500 lbs | 5,000 | High-capacity applications |
| 41x41x60 | 41" x 41" x 60" | ~58.4 | 4,000 - 4,500 lbs | 5,500 | Light density materials, recycling |
| 42x42x42 | 42" x 42" x 42" | ~42.9 | 3,000 - 3,800 lbs | 4,000 | Cubic pallet-fit, warehouse storage |
| 42x42x50 | 42" x 42" x 50" | ~51.0 | 3,500 - 4,400 lbs | 4,600 | Industrial, mining, chemicals |
| 44x44x44 | 44" x 44" x 44" | ~49.2 | 3,500 - 4,200 lbs | 4,600 | Standard pallet optimization |
| 44x44x50 | 44" x 44" x 50" | ~55.9 | 4,000 - 4,800 lbs | 5,000 | High-volume industrial |
| 45x45x45 | 45" x 45" x 45" | ~52.7 | 4,000 - 4,500 lbs | 5,000 | General industrial, food grade |
| 45x45x50 | 45" x 45" x 50" | ~58.6 | 4,200 - 5,000 lbs | 5,500 | Large capacity applications |
* Volumes are calculated as (W × D × H) ÷ 1728 cubic feet. Actual usable volume depends on bag construction and fill factor.
* Capacity ranges based on typical bulk densities. Dense materials will fill to lower volumes; light materials may exceed volume capacity before reaching SWL.
* Safe Working Load (SWL) values are typical maximums. Actual SWL depends on fabric weight, construction, and safety factor rating.
Bulk Density & Size Recommendations
Use bulk density to determine the right bag size for your material
| Material | Bulk Density (lb/cu ft) | Recommended Size |
|---|---|---|
| Sand (dry) | 100-110 | 35x35x40 |
| Gravel | 95-100 | 35x35x40 |
| Cement | 85-95 | 35x35x45 |
| Grain (wheat) | 45-50 | 37x37x55 |
| Corn | 44-48 | 37x37x55 |
| Rice | 50-55 | 35x35x50 |
| Flour | 35-40 | 37x37x60 |
| Sugar (granulated) | 50-55 | 35x35x50 |
| Salt | 70-80 | 35x35x45 |
| Fertilizer (granular) | 55-65 | 35x35x50 |
| Wood pellets | 40-45 | 37x37x55 |
| Plastic pellets | 30-40 | 37x37x60 |
| Coal | 50-60 | 36x36x60 |
| Limestone (crushed) | 85-95 | 35x35x45 |
What is Bulk Density?
Bulk density measures how much weight fits in a given volume, expressed as pounds per cubic foot (lb/cu ft). It's crucial for bag selection because:
- Dense materials (sand, gravel) hit weight limits before volume limits - use shorter bags with high SWL
- Light materials (flour, pellets) hit volume limits before weight limits - use taller bags for efficiency
- Moderate density materials need balanced selection considering both factors
Calculation:
Required Volume = Target Weight ÷ Bulk Density
Example: 2,000 lbs of grain (45 lb/cu ft) = 44.4 cu ft needed
How to Calculate Your Ideal Bag Size
Follow these steps to determine the perfect bulk bag dimensions for your specific material and application.
Determine Your Material's Bulk Density
Look up or measure your material's bulk density in lb/cu ft. If unsure, contact your material supplier or use the reference table above.
Calculate Required Volume
Target Weight (lbs) ÷ Bulk Density (lb/cu ft) = Volume Needed (cu ft)
Add Fill Factor Buffer (10-15%)
Volume Needed × 1.15 = Adjusted Volume (cu ft)
Select Bag Meeting Both Criteria
Choose a bag where: Volume ≥ Adjusted Volume AND SWL ≥ Target Weight
Example A: Heavy Material (Sand)
Target: 2,200 lbs of sand
Bulk Density: 100 lb/cu ft
Volume: 2,200 ÷ 100 = 22 cu ft
With Buffer: 22 × 1.15 = 25.3 cu ft
Recommendation: 35x35x40 (28 cu ft, 2,500 lb SWL)
Weight limit is the controlling factor - bag will be ~75% full by volume
Example B: Light Material (Flour)
Target: 1,500 lbs of flour
Bulk Density: 35 lb/cu ft
Volume: 1,500 ÷ 35 = 42.9 cu ft
With Buffer: 42.9 × 1.15 = 49.3 cu ft
Recommendation: 41x41x50 (48.7 cu ft, 4,600 lb SWL)
Volume is the controlling factor - bag will be at capacity by volume, well under SWL
Size Recommendations by Industry
Tailored bulk bag size recommendations for specific industries and applications
Agriculture & Farming
Agricultural materials like grain, seeds, and feed require taller bags to maximize volume while staying within weight limits. Most farm equipment can handle standard 35-37 inch base dimensions.
Recommended Sizes:
Common Materials:
Grain, seeds, animal feed, fertilizer, hay pellets, dried produce
Key Considerations:
Consider ventilated bags for moisture-sensitive crops. Food-grade liners for human consumption products.
Construction & Aggregates
Construction materials are often dense and heavy. Shorter, wider bags provide stability and are easier to handle on job sites. Higher SWL ratings are essential.
Recommended Sizes:
Common Materials:
Sand, gravel, crusite, concrete mix, asphalt aggregates, soil
Key Considerations:
UV-stabilized fabric for outdoor storage. Ensure bags meet or exceed weight requirements.
Chemical & Pharmaceutical
Chemical applications require specific bag types based on product characteristics. Static dissipative bags for flammable materials. Coated interiors for moisture protection.
Recommended Sizes:
Common Materials:
Industrial chemicals, resins, polymers, pharmaceutical intermediates
Key Considerations:
Type B, C, or D bags for static control. Consider liner options for moisture and contamination protection.
Food & Beverage
Food-grade applications require bags manufactured in certified facilities with strict hygiene standards. UN food-grade certification is often required.
Recommended Sizes:
Common Materials:
Flour, sugar, rice, coffee beans, spices, food additives, starch
Key Considerations:
Must meet FDA requirements. Consider virgin polypropylene and food-safe liners.
Mining & Minerals
Mining operations handle heavy, abrasive materials. Extra-heavy fabric weight and reinforced seams are essential. Higher safety factors recommended.
Recommended Sizes:
Common Materials:
Ore concentrates, minerals, coal, limestone, gypsum, salt
Key Considerations:
6:1 safety factor for heavy materials. UV protection for outdoor stockpiling.
Recycling & Waste
Recycling facilities need high-volume bags for lightweight materials. Open top designs for easy loading. Bottom discharge for efficient unloading.
Recommended Sizes:
Common Materials:
Plastic pellets, recycled materials, wood chips, paper waste
Key Considerations:
Ventilated options for moisture control. Wide opening for mixed materials.
Safety Factor Ratings
Understanding safety factors is essential for proper bulk bag selection and safe operation
Single Trip
Standard industry safety factor for single-use applications. The bag will break at 5 times the stated Safe Working Load.
Best For:
One-time transport, short-term storage, non-hazardous materials
Example:
A bag with 2,000 lb SWL has been tested to hold 10,000 lbs before failure.
Multi-Trip
Higher safety margin required for bags that will be reused multiple times. Accounts for wear and tear from repeated use.
Best For:
Reusable applications, closed-loop systems, repeated handling
Example:
A bag with 2,000 lb SWL has been tested to hold 12,000 lbs before failure.
Heavy-Duty
Premium safety factor for critical applications. Provides maximum safety margin for valuable or hazardous contents.
Best For:
Hazardous materials, high-value contents, extended storage
Example:
A bag with 2,000 lb SWL has been tested to hold 16,000 lbs before failure.
Important Safety Information
- Never exceed the Safe Working Load (SWL) - The safety factor is NOT extra capacity; it is a margin of safety.
- Inspect bags before each use - Check for damage, UV degradation, contamination, and wear on lifting loops.
- Use appropriate lifting equipment - Ensure forklifts and cranes are rated for the loaded bag weight.
- Consider dynamic loads - Sudden movements, drops, and swinging increase effective loads on bags.
- Follow proper stacking guidelines - Most bags are NOT designed for stacking. Verify before stacking.
Safe Working Load (SWL) Explained
Understanding weight limits and load ratings for bulk bags
What is Safe Working Load?
Safe Working Load (SWL) is the maximum weight that a bulk bag is designed to safely hold during normal use conditions. It is NOT the weight at which the bag will break - that would be the breaking strength, which is always significantly higher due to the safety factor.
The Relationship:
Breaking Strength = SWL × Safety Factor
A bag with 2,000 lb SWL and 5:1 SF has a breaking strength of 10,000 lbs
Standard SWL Ratings
Factors Affecting SWL
Fabric Weight (GSM)
Heavier fabric = higher SWL. Standard is 150-200 GSM; heavy-duty is 200+ GSM.
Seam Construction
Double or triple stitched seams, along with proper overlap, increase strength.
Lifting Loop Attachment
How loops are sewn to the bag body affects overall lift capacity.
Bag Design
U-panel and circular bags often have higher SWL than 4-panel designs.
Coatings & Liners
Some coatings add structural integrity; liners generally do not affect SWL.
Fill & Discharge Spout Options
Spout configurations affect filling speed, discharge control, and equipment compatibility
Fill Spout (Top)
Fill spouts provide controlled, dust-free filling. Larger diameters allow faster fill rates but may require specific equipment.
Available Diameters:
Length Options:
12", 18", 24", 30" standard lengths available
Recommendation:
Match spout diameter to your filling equipment. 14" is most common for general use.
Discharge Spout (Bottom)
Discharge spouts allow controlled emptying. Tied closed for storage and transport, untied for gravity discharge.
Available Diameters:
Length Options:
12", 18", 24" standard lengths available
Recommendation:
Consider flow characteristics of your material. Wider spouts for free-flowing, narrower for controlled discharge.
Alternative Top & Bottom Configurations
Open Top
Full opening without a spout. Ideal for large items, rapid filling, or materials that don't require dust control. Often used with a duffle cover for closure.
Duffle Top
Open top with a fabric cover that folds over and ties closed. Provides dust protection while maintaining easy access for filling.
Flat Bottom
Sewn closed at bottom with no discharge option. Contents must be dumped by inverting the bag or scooped out manually.
Full Discharge Bottom
Large opening at bottom for complete, rapid discharge. Used when speed is critical and controlled flow is not required.
Custom Bulk Bag Sizes
When standard sizes do not meet your needs, custom configurations are available
When to Consider Custom Sizes
- Your material has unique properties requiring specific dimensions
- Your filling or discharge equipment has non-standard specifications
- Storage or transportation constraints require specific dimensions
- You need to optimize pallet utilization for your warehouse
- Your application requires non-standard capacity or SWL
- Regulatory requirements dictate specific bag specifications
Customizable Parameters
Dimensions
- Any width from 24" to 60"
- Any depth from 24" to 60"
- Any height from 24" to 84"
- Rectangular (non-square) bases available
Specifications
- SWL from 500 lbs to 6,000+ lbs
- 5:1, 6:1, or 8:1 safety factors
- Fabric weights from 100 to 300 GSM
- Custom spout sizes and lengths
Features
- Food-grade certification
- Conductive/static control (Types B, C, D)
- Coatings and liners
- Document pouches and labels
- Custom printing and branding
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Our team can help design the perfect bulk bag for your specific requirements. Minimum order quantities may apply for custom sizes.
Contact Our TeamSize Comparison
Visual representation of common bulk bag sizes relative to a standard pallet
35x35x40
~28 cu ft
2,000-2,500 lbs
Compact35x35x50
~35 cu ft
2,500-3,000 lbs
Standard36x36x60
~45 cu ft
3,200-4,000 lbs
Tall41x41x45
~44 cu ft
3,000-4,000 lbs
Wide41x41x55
~54 cu ft
3,800-4,500 lbs
Large45x45x45
~53 cu ft
4,000-4,500 lbs
Cubic* Visual representations are proportional but not to exact scale. Actual bags will appear different when filled due to material characteristics.
Sizing FAQ
Answers to frequently asked questions about bulk bag sizes and selection
How do I measure bulk bag dimensions?
Bulk bag dimensions are stated as Width x Depth x Height in inches. Width and depth refer to the base dimensions, while height is measured from the bottom seam to the top seam (excluding loops and spouts). For example, a 35x35x50 bag has a 35" x 35" base and is 50" tall.
What is the difference between SWL and breaking strength?
Safe Working Load (SWL) is the maximum weight you should put in the bag during normal use. Breaking strength is the actual weight at which the bag will fail. The ratio between them is the safety factor. Never exceed the SWL - the safety factor exists to account for dynamic loads, handling stress, and material degradation.
Can bulk bags be stacked when full?
Most standard bulk bags should NOT be stacked when full unless specifically designed for it. If stacking is required, look for bags with stacking frames, formable designs, or use external support structures. Never stack more than two high without engineering verification.
How do I calculate the volume I need?
Divide the weight of material by its bulk density to get volume in cubic feet. Add 10-15% for fill factor (material never fills perfectly). Then select a bag with volume greater than your calculated need AND an SWL that exceeds your material weight.
What size fits on a standard pallet?
Standard pallets are 40" x 48". Bags with 35-42" base dimensions fit well on standard pallets. For optimal pallet utilization, consider 40x40 or 42x42 base dimensions. Remember that filled bags will "mushroom" slightly, so allow some clearance.
Should I choose a taller or wider bag?
For dense, heavy materials - choose shorter, wider bags for stability. For light, fluffy materials - choose taller bags to maximize volume. Consider your filling and discharge equipment, storage space, and handling requirements.
What is the fill factor and why does it matter?
Fill factor accounts for the fact that bulk materials never fill a container to 100% of its theoretical volume. Voids between particles, settling, and headspace all reduce actual capacity. Typically, expect 85-90% of theoretical volume, hence the 10-15% buffer recommendation.
Do I need a liner for my bulk bag?
Liners provide moisture protection, contamination barriers, and easier discharge for sticky materials. Consider liners for hygroscopic materials, food products, fine powders, or when complete discharge is critical. Form-fit liners conform to the bag shape; loose liners allow for extraction.
What is a baffle bag and when do I need one?
Baffle bags have internal panels that help maintain a cubic shape when filled, improving stacking stability and storage efficiency. Use baffle bags when you need to maximize warehouse space, stack bags, or when appearance matters for retail display.
How does humidity affect bag selection?
For materials sensitive to moisture, consider: coated fabric (polyethylene or polypropylene coating), polyethylene liners, or sealed spout closures. For materials that need to breathe, choose uncoated fabric or ventilated designs. Climate and storage conditions should influence your selection.
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