When you are specifying a corrugated box from a manufacturer in India, one of the first decisions is flute type. The flute is the wavy medium layer inside the corrugated board. Its size and shape determine the board's thickness, compression strength, cushioning performance, and printability. Choosing the wrong flute for your application can mean boxes that crush in transit, cost more than necessary, or fail a retailer's vendor compliance audit.
This guide covers the four flute types most commonly used in export packaging - B, C, E, and BC double wall - with clear guidance on when to use each.
What Is a Flute?
Corrugated board consists of one or more flat sheets (liners) bonded to a wavy sheet (the fluted medium). The flute runs the full length of the board and creates a series of arched columns when viewed from the cut edge. These arches give corrugated board its compression strength - they work in the same structural way as an arch bridge, transferring load into the liner rather than buckling under it.
Flute type is defined by two values: flute height (the distance from the base to the peak of each arch) and flute count (the number of flutes per linear metre). Higher, wider flutes give more cushioning and stack strength. Smaller, tighter flutes give better printing surface and a smoother, stiffer panel.
Standard corrugated boards are classified as 3-ply (one fluted medium between two liners), 5-ply (double wall - two fluted layers), or 7-ply (triple wall). Most export boxes are 3-ply or 5-ply.
B Flute
Flute height: approximately 3.0mm Flutes per metre: approximately 150
B flute is a compact, high-density profile. Its shorter arches pack closely together, giving the board a stiffer, smoother surface than C or A flute. This makes B flute the preferred choice when printability and panel rigidity matter more than maximum cushioning.
Best for:
- Retail display boxes and shelf-ready packaging
- Canned goods, bottles, and glass where panel stiffness prevents flex damage
- Die-cut boxes with complex fold patterns (the tighter flute holds crease lines cleanly)
- Point-of-sale (POS) displays
Not ideal for:
- Long-haul sea freight of fragile items (cushioning is lower than C flute)
- Heavy goods stacked in high columns
B flute is widely used for secondary packaging in retail environments. If your product sits on a shelf in its corrugated box, or if you need a sharp, clean print on the box surface, B flute is usually the correct choice.
C Flute
Flute height: approximately 4.0mm Flutes per metre: approximately 127
C flute is the most widely used corrugated profile in global shipping. Its taller arches provide better cushioning than B flute while still maintaining good panel stiffness and a printable surface. The combination of cushioning, strength, and printability makes C flute the default specification for general-purpose export cartons.
Best for:
- Most shipped goods: electronics, clothing, hardware, agricultural products
- Products that need protection from vibration and minor impacts in transit
- FCL and LCL sea freight shipments from India to the USA and UK
- Boxes that will be printed with logos and shipping information
Not ideal for:
- Very heavy goods (over 25 kg per box) without reinforcement or inner packaging
- Extreme stacking loads in damp conditions
If you are specifying your first corrugated box from India and are unsure where to start, C flute is the safe, proven starting point. It handles the widest range of products and transit conditions without modification.
E Flute
Flute height: approximately 1.5mm Flutes per metre: approximately 290
E flute is the thinnest standard corrugated profile. Its very tight, fine flute pattern creates a board that is closer in character to a thick grey board or mount board than to traditional corrugated. E flute is very stiff, very smooth, and very well-suited to high-quality printing - including offset-laminated full-colour artwork.
Best for:
- Retail gift packaging and premium product boxes
- Food service packaging (pizza boxes, bakery boxes, take-away cartons)
- Small consumer electronics packaging
- Cosmetics and health product outer boxes
- Any application where a premium print finish is required on a corrugated substrate
Not ideal for:
- Heavy-duty export or long sea freight transit
- Products that need cushioning - E flute has minimal impact absorption
- Large boxes (the thin profile is best suited to smaller formats)
E flute is chosen when the box is part of the product experience - when the customer sees and handles the box as part of retail or premium unboxing. For export transit, E flute is usually reserved for inner packaging or display boxes, with a heavier outer corrugated carton used for the outer shipping unit.
BC Double Wall
Combined height: approximately 7.0mm (B + C layers) Wall construction: 5-ply (three liners, two fluted mediums)
BC double wall combines a B flute layer and a C flute layer bonded together with a centre liner between them. The result is a board that is significantly stronger than any single-wall profile, with the C flute layer contributing cushioning depth and the B flute layer contributing surface stiffness and printability.
Best for:
- Heavy goods: machinery components, industrial hardware, bulk agricultural products
- Products requiring high BCT (Box Compression Test) for tall stacking in containers
- Items that need both cushioning (C layer) and a decent print surface (B layer)
- Fragile goods on long sea freight transits where single-wall would be borderline
Not ideal for:
- Lightweight products where the additional board weight and cost add no value
- Applications where box weight is restricted (air freight, weight-sensitive retail)
BC double wall is the most common double-wall specification for export from India. It provides a meaningful strength step up from single-wall C flute without the full thickness of AC or AA double wall, and the B-flute face allows acceptable flexographic print quality.
Flute Type Comparison Table
| Flute | Height | Strength | Cushioning | Print Quality | Best Use |
|---|---|---|---|---|---|
| E | 1.5mm | Low | Minimal | Excellent | Premium retail, pizza boxes |
| B | 3.0mm | Medium | Low-medium | Very good | Retail display, canned goods |
| C | 4.0mm | Medium-high | Good | Good | General export shipping |
| BC | 7.0mm | High | Very good | Good (B face) | Heavy goods, industrial export |
How to Choose the Right Flute
If your product is light and the box will sit on a retail shelf: E or B flute.
If your product ships in a standard export carton by sea freight: C flute.
If your product is heavy (over 15 kg) or fragile on long transit: BC double wall, or C flute with internal void fill. Our guide on heavy-duty corrugated boxes for export shipping covers double-wall and triple-wall constructions in detail, including ECT ratings and load limits for export applications.
If you need high-quality colour printing on the outer surface: E flute for premium, B flute for standard, C flute for basic.
If you are unsure: request samples in both C and BC from your manufacturer. The cost difference is small on a sample; the cost difference on a failed shipment is significant.
A Note on Liner Grade
Flute type determines the board's structural profile, but liner grade determines the board's actual strength. Two boxes can use the same C flute with very different burst strength ratings depending on whether the liners are 100 GSM test liner or 150 GSM kraftliner. When specifying a box, always state both the flute type and the liner GSM or the required burst factor (BF) or ECT (Edge Crush Test) value.
A manufacturer who only asks for box dimensions without asking about liner grade or required strength is not asking the right questions. A well-specified corrugated box order will always include: dimensions (L x W x H), flute type, liner grade (or strength requirement), ply count, and printing specification. Our corrugated box sizes and grades guide explains common board grade formats and how to read ECT and GSM specifications when comparing quotes from Indian manufacturers.
Sourcing Corrugated Boxes from India by Flute Type
Indian corrugated manufacturers produce all standard flute types in-house. B, C, E, and BC double wall are all standard production specifications, with no tooling premium for choosing one over another. The cost difference between flute types comes from raw material - more paper per square metre for double wall, different GSM liner specifications for different strength grades.
For exporters in the USA and UK, factory-direct sourcing from India typically offers 30 to 50% savings versus domestic purchasing, even after sea freight costs. The key is specifying correctly upfront and requesting test data - burst strength, BCT, and GSM certificates - with your samples.
For detailed specification guides by box type, see our pages on RSC corrugated boxes, double wall corrugated boxes, and custom printed corrugated boxes.
Whizzpack manufactures corrugated boxes in B, C, E, and BC double wall at our factory in Rajkot, Gujarat, and exports factory-direct to importers across the USA and UK. Visit our corrugated boxes page to discuss your flute specification and request samples.