Corrugated board basics
Decode paper grades, compare flutes and box styles, and measure your carton correctly. Practical answers to help you specify a better pack.
01 / Inside the board
Single-wall board brings two flat liners and one fluted medium together. Here is how K150 / M120 / T150 describes those individual papers.
Kraft liner · 150 gsm
The outer paper surface.
Corrugating medium · 120 gsm
The wave between the liners.
Test liner · 150 gsm
The inner paper surface.
Illustrative paper combination. Confirm the layer order and flute when specifying a carton; a paper code alone is not a tested load capacity.
02 / Wall construction
The fluted paper creates air columns between liners. Those columns help the finished board resist crushing and absorb handling impact.
2 liners / 1 medium
A practical choice for many shipping, storage and retail cartons when the product weight and stacking load are moderate.
3 liners / 2 mediums
Additional layers provide greater rigidity, puncture resistance and stacking support for more demanding distribution conditions.
Triple wall uses four liners and three fluted mediums. It is reserved for very heavy-duty requirements; BAB and ABA reference profiles are included in the flute table below.
03 / Paper selection
The outside colour alone does not prove paper type or strength. Compare the material, then choose the grade and board combination for the product journey.
K / kraft liner
Kertas pelapik kraft
Standard kraft paper is not waterproof.
T / test liner
Kertas pelapik kitar semula
Recycled liner can still be specified for shipping cartons when the complete board is suitable.
M / corrugating medium
Kertas beralun
Medium is an internal structural paper, not an outer-liner substitute.
A brown carton may use kraft liner, recycled liner or a combination of both. Confirm the specification instead of judging by colour.
150 gsm vs 175 gsm
GSM means grams per square metre of paper. A 175 gsm paper has more mass per unit area than a 150 gsm paper, but this is not a guaranteed increase in carton strength.
Read the complete specification
Ask which layer the GSM refers to. Compare the paper grade, flute profile and full board combination, then confirm the carton size and performance required.
These are Newbox reference grades. Final availability and the suitable paper combination are confirmed for each order.
| Paper | Symbol | GSM | Pound |
|---|---|---|---|
| Kraft liner | K | 280 / 275 | 64 lb |
| Kraft liner | K | 180 / 175 | 42 lb |
| Kraft liner | K | 150 | 33 lb |
| Test liner | T | 280 / 275 | 64 lb |
| Test liner | T | 180 / 175 | 42 lb |
| Test liner | T | 150 | 33 lb |
| Test liner | T | 125 | 26 lb |
| Corrugating medium | M | 180 / 175 | 42 lb |
| Corrugating medium | M | 150 | 33 lb |
| Corrugating medium | M | 120 | 26 lb |
| Corrugating medium | M | 100 | 23 lb |
| White liner | W | 180 / 175 | 42 lb |
| Conductive liner | C | 180 / 175 or 150 | 42 or 33 lb |
04 / Flutes & thickness
The wave changes the board’s profile. A flute is deeper; B flute is more compact. C and E provide other thickness options for different packaging needs.
B flute / approx. 3.0 mm
Smaller, closer flutes offer a relatively smooth printing surface and a slimmer pack. Commonly considered for general cartons.
A flute / approx. 5.0 mm
Taller flutes add thickness and cushioning. Choose the liners and internal protection to suit the product and its journey.
Neither thickness nor flute letter alone guarantees a stronger carton. Paper grade, construction and finished-carton performance also matter.
| Construction | Flute | Approx. thickness | Common reason to consider it |
|---|---|---|---|
| Single wall | A | 5.0 mm | Thicker cushioning and vertical compression support |
| Single wall | B | 3.0 mm | Good rigidity with a compact profile |
| Single wall | E | 1.5 mm | Fine flute for compact packs and better presentation |
| Single wall | C | 4.0 mm | Less commonly selected; balanced cushioning and stacking when specified |
| Double wall | BA | 8.0 mm | Heavy-duty stacking, cushioning and protection |
| Double wall | BE | 4.5 mm | Strength with a slimmer profile and smoother surface |
| Triple wall | BAB | 11.0 mm | Very heavy-duty protection and stacking support |
| Triple wall | ABA | 13.0 mm | Maximum reference thickness for demanding loads |
Why approximate? Finished thickness can vary slightly with paper grade, moisture, corrugating pressure, adhesive and normal production tolerance between runs or suppliers. Values shown are Newbox's nominal material reference.
05 / Carton styles
RSC, HSC and 5PF describe the carton’s construction. Choose the style separately from the paper grade and flute.
RSC
Top and bottom flaps close the carton. The outer flaps meet at the centre.
Common use
Everyday shipping and storage.
Look for: top and bottom flaps.
HSC
Bottom flaps close the base; the top stays open. A separate lid can be specified.
Common use
Top loading or packing with a separate cover.
Look for: an open top without flaps.
5PF
A scored sheet wraps around the product, with an overlapping panel for closure.
Common use
Long or narrow items that are easier to wrap.
Look for: the wrap-around panel.
Generated visual references for style identification. Final proportions, flaps and closure follow your approved carton drawing.
06 / Measuring your carton
Measure the finished box from one outermost edge to the opposite outermost edge. Record every dimension in millimetres and send them in Newbox order: L × W × H.
Outside-size example: 400 × 300 × 250 mm means Length 400 mm, Width 300 mm and Height 250 mm.
Newbox’s enquiry form asks for outside dimensions. For product fit, share the product dimensions and cushioning space, or clearly label the internal size needed. Measure the assembled box with flaps closed: length is the longer side of the opening, width the shorter side, and height is base to top. Do not include open flaps.
07 / Strength & stacking
Two useful tests answer different questions. Ask for the result, units and test conditions when comparing specifications.
Measures a board sample’s resistance to compression on its edge. Usually reported in kN/m or lb/in.
Useful for comparing board performance, but it does not by itself establish a finished carton’s load limit.
Measures the assembled carton’s resistance to compression under defined conditions. Commonly reported in N or kN.
Helps assess stacking performance. Confirm the box design, conditioning and test setup with the result.
A BCT result is not the weight you can safely put inside a carton or leave stacked on it indefinitely. Storage duration, humidity, pallet support, stacking arrangement and handling affect real performance.
Before requesting a quote
These details allow our team to recommend a board instead of guessing from one term such as “double wall.”
Weight per item and the total packed weight.
Length × Width × Height in millimetres.
How high and how long cartons will be stored.
Local delivery, courier, palletised transport or export.
Moisture, cold room, manual handling or rough movement.
Estimated order volume plus print or branding needs.
Plan your order
Yes, samples are free. Delivery charges apply for sample deliveries outside Melaka. Share your product details and the carton specification you would like to try with our team.
Production usually takes 3–7 business days. Delivery transit time is separate and depends on your location. Contact our team to confirm the production schedule and delivery arrangement for your order.
Using the notation in this guide, K150 is kraft liner at 150 grams per square metre, M120 is corrugating medium at 120 gsm, and T150 is test liner at 150 gsm. If listed outside to inside, these describe the three papers in a single-wall board. Confirm the layer order and flute with your supplier: these codes are not a universal strength rating.
B flute has a more compact profile, about 3 mm in the Newbox reference, and provides a relatively smooth surface for printing. A flute is about 5 mm and offers more cushioning. Choose the complete board for the product and delivery conditions; flute letters alone do not guarantee stacking strength.
GSM means grams per square metre of paper. A 175 gsm paper is heavier per unit area than 150 gsm paper, but it does not automatically make the carton stronger. Ask which layer the number describes, and compare paper grade, flute, full board construction and relevant test results.
Kraft liner is made mainly from virgin kraft fibre; test liner mainly uses recovered fibre. Both can be used in shipping cartons. Compare the specified paper performance and complete board construction. Brown colour alone does not identify the fibre content, and neither standard liner is waterproof.
RSC means regular slotted carton, with top and bottom flaps that close the carton. HSC means half slotted carton, with one open end and flaps at the other; a separate lid can be specified. 5PF means five-panel folder, which wraps around the product and can suit long or narrow items. Confirm the drawing, closure and any separate lid.
For the Newbox enquiry form, give outside length x width x height in millimetres, measured on the assembled carton with flaps closed. Length is the longer side of the opening, width the shorter, and height runs from base to top. If you only know the product size or internal space needed, label it clearly and allow for cushioning. Internal and external dimensions are not interchangeable.
The box compression test (BCT) measures how a finished carton resists compression under stated test conditions, commonly reported in N or kN. It helps assess stacking performance. A laboratory result is not a safe packed-weight or long-term stacking limit: humidity, storage time, pallet support and handling also matter.
No. The edge crush test (ECT) measures the edgewise compression resistance of a board sample, usually in kN/m or lb/in. BCT tests the assembled carton. ECT is useful when specifying board, but carton dimensions, joints, openings and construction also affect finished-box performance.
No. A correctly specified single-wall carton can suit many products. Double wall adds layers and thickness for more demanding protection or stacking requirements, but the full paper combination and finished design still need to suit the pack.
There is no reliable weight limit from GSM or flute alone. Share the total packed weight, dimensions, product support, stacking height and duration, plus the delivery route. A suitable specification and, where needed, packed-product testing are the basis for a recommendation.
Not necessarily. Fragile products may need dividers, corner protection or cushioning to stop movement and keep them away from the carton walls. Assess the complete packed product for the handling and transport it will face.
Moisture can reduce paperboard performance. Explain any humidity, condensation, cold-room or wet handling exposure before selecting the board. Suitable papers, treatments and testing may be needed; ordinary corrugated board is not waterproof.
A sample helps identify its style, dimensions and construction. Send any printed board code and explain how the pack is used. Appearance alone cannot confirm the original paper grade or strength; ask for the proposed replacement specification and validate it for your product.
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