Flyer Bag or Carton Box? How Volumetric Weight Decides What You Actually Pay
Short answer: Malaysian couriers charge you on whichever is higher — the parcel’s actual weight or its volumetric weight. Volumetric weight is length × width × height in centimetres, divided by a fixed number: J&T Express states 6,000 for domestic parcels and 5,000 for international, and most other couriers work on 5,000. That means a box gives you roughly 6 litres of space per kilogram before you start paying for air. A flyer bag wins when your item is light and squashable, because it barely adds volume. A carton box wins when the item is fragile, rigid, or dense enough that its actual weight is charged anyway. The mistake that costs sellers the most money is not choosing wrong — it is shipping a right-choice box that is two sizes too big.
If your courier bill feels higher than the weight on your kitchen scale suggests, this is almost always why.
The formula, and the number that matters
Every courier quote runs the same comparison:
- Actual weight — what the parcel weighs on the scale.
- Volumetric weight — (L × W × H in cm) ÷ divisor.
You are charged on the larger of the two. J&T Express Malaysia’s own FAQ puts it plainly: volumetric weight is length × width × height ÷ 6,000 for domestic, ÷ 5,000 for international, and “actual weight and volumetric weight are considered in the actual shipping cost whichever is higher.”
The divisor is the whole game. On a ÷6,000 divisor, every 6,000 cm³ of parcel counts as 1 kg. On ÷5,000, every 5,000 cm³ counts as 1 kg — the same box costs you 20% more chargeable weight. Check which divisor your courier or aggregator applies before you standardise on a box size, because the two are not interchangeable.
Box size to volumetric weight
Here is what common carton sizes convert to. Find your box, then compare against what your product actually weighs.
| Box (L × W × H, cm) | Volume | Volumetric weight ÷6,000 | Volumetric weight ÷5,000 |
|---|---|---|---|
| 25 × 20 × 15 | 7,500 cm³ | 1.25 kg | 1.50 kg |
| 30 × 20 × 15 | 9,000 cm³ | 1.50 kg | 1.80 kg |
| 32 × 22 × 18 | 12,672 cm³ | 2.11 kg | 2.53 kg |
| 35 × 25 × 20 | 17,500 cm³ | 2.92 kg | 3.50 kg |
| 40 × 30 × 20 | 24,000 cm³ | 4.00 kg | 4.80 kg |
| 45 × 35 × 25 | 39,375 cm³ | 6.56 kg | 7.88 kg |
| 50 × 40 × 30 | 60,000 cm³ | 10.00 kg | 12.00 kg |
Read one row closely. A 40 × 30 × 20 box holding a 1.2 kg item is billed as a 4 kg parcel on a ÷6,000 divisor — more than three times the weight you actually shipped. The same goods in a flyer bag measuring roughly 35 × 25 × 5 come to 4,375 cm³, or 0.73 kg volumetric, so the 1.2 kg actual weight is what gets charged. That is the difference between a 1 kg rate and a 4 kg rate, on every single order, for the life of that product listing.
The 6-litre rule
You do not need the calculator every time. On a ÷6,000 divisor:
Every kilogram of actual weight “buys” you 6 litres (6,000 cm³) of parcel space. Use less and you pay actual weight. Use more and you pay for air.
So a 1 kg product is fine in anything up to about 25 × 20 × 12 cm. A 3 kg product can fill an 18,000 cm³ box — roughly 35 × 25 × 20 — without adding a sen. On a ÷5,000 divisor, drop that allowance to 5 litres per kilogram.
This flips the usual instinct. Heavy products are rarely the volumetric problem; they are dense, so actual weight wins the comparison and the box is effectively free. The parcels that bleed money are the light, bulky ones — pillows, plush toys, apparel bundles, empty containers, anything foam-filled.
When each one actually wins
Use a flyer bag when:
- The item is soft, flexible, or non-fragile — clothing, textiles, accessories, printed matter.
- Nothing inside can be crushed, snapped, or bent out of shape.
- The product is light and bulky, so volumetric weight is your binding cost.
- You are shipping high volume and want faster packing and near-zero storage space for empties.
Use a carton box when:
- The item is fragile, rigid, or has corners and edges that need protecting.
- It is dense enough that actual weight exceeds volumetric anyway — the box costs you nothing extra in freight.
- It must be stacked in transit without deforming.
- Presentation matters, or the parcel needs to survive a return trip.
Most catalogues split cleanly. Sort your products into those two buckets once, fix a packing method for each, and stop deciding order by order — case-by-case guessing is what produces both over-packed parcels and damaged ones.
Cut the box down instead of buying another size
If your box is right in footprint but too tall, you do not need a new SKU. Score the four side walls at the height you actually need, fold the excess inward, and tape the flaps down over it. You keep the box’s footprint and stacking strength, remove the empty headroom, and cut the volumetric weight in the process.
Taking a 40 × 30 × 20 box down to 40 × 30 × 10 halves the volume — from 4.00 kg to 2.00 kg volumetric on a ÷6,000 divisor. It costs you thirty seconds and a strip of tape.
The other half of the same job is filling voids properly. Empty space inside a box is what lets contents shift and break, and padding it with bubble wrap adds negligible weight — bubble wrap is almost entirely air, so it protects the item without moving the actual-weight number in any meaningful way.
A quick pre-ship checklist
- Measure the packed parcel at its widest points, not the flat box specs.
- Divide by your courier’s divisor — confirm whether it is 5,000 or 6,000.
- Compare against the scale weight; the higher number is your bill.
- If volumetric wins by a wide margin, go down a box size or switch to a flyer bag.
- Check the courier’s maximum dimensions too. J&T’s FAQ lists a 300 cm limit on L + W + H, with no single side over 120 cm; other couriers set their own caps, and oversize surcharges are separate from weight.
FAQ
What is volumetric weight in simple terms? It is a way for couriers to charge for the space a parcel occupies rather than just its weight, because a van fills up on volume long before it hits its weight limit. You take length × width × height in centimetres and divide by the courier’s divisor to get a weight in kilograms, then pay on whichever is higher — that figure or the scale weight.
Is the divisor always 5,000 in Malaysia? No, and this catches people out. J&T Express states 6,000 for domestic shipments and 5,000 for international ones in its own FAQ, while ÷5,000 is the common general figure quoted across Malaysian courier guides. Confirm the divisor with the courier or aggregator you actually book through, since the same box can be charged 20% heavier under ÷5,000.
Are flyer bags always cheaper to ship than boxes? Not always — only when volumetric weight is what is being charged. If your product is dense enough that its actual weight already exceeds the box’s volumetric weight, the box costs nothing extra in freight and you get much better protection for free. Flyer bags win decisively on light, bulky, non-fragile goods.
Does bubble wrap or padding push my shipping cost up? Barely, in weight terms. Padding is mostly air, so it adds very little to actual weight. What raises your cost is padding that forces you into a larger box — protect the item, but choose the box around the padded item rather than padding out a box you have already chosen.
Can I use a once-used box for e-commerce orders? Yes, as long as it is clean, uncrushed, and the flaps still fold flat with walls that have not been compressed by a previous heavy load. Grade-A once-used cartons cost about half of new, and for the outer layer of a parcel the box mainly needs to hold its shape under stacking — the internal wrapping is what protects the product.
Getting your packing sizes right in one order
If you are still shipping everything in one or two box sizes because that is what you happen to stock, that is usually where the savings are. Quinocycle carries new and once-used Grade-A cartons across a wide size range, plus flyer bags, bubble wrap, and tape — so you can match the box to the product instead of the other way round, and once-used cartons come in at roughly half the price of new.
Not sure which sizes suit your catalogue? Send us your product dimensions on WhatsApp at +6016 891 6381 and we will point you to the sizes that fit, or browse the full range on our help page. We deliver across Peninsular Malaysia from Balakong, Selangor.