Volumetric weight: why a light parcel can cost like a heavy one
An aircraft runs out of space before it runs out of lifting capacity, so every express carrier charges for the room a parcel takes up when that is worth more than its weight on the scale. The rule is simple once you have seen the formula; the surprises come from the boxes people choose.
By Ravi Shrivastav, founder, ExpressBox · Updated 27 Oct 2026
The formula
Measure the outer length, width and height of the box in centimetres, multiply them together, and divide by 5,000. The result is the volumetric weight in kilograms. The carrier compares it with the actual weight and bills the greater of the two, rounded up to the next 0.5 kg. The 5,000 divisor is the IATA standard for express air; economy or postal services sometimes use 6,000, which is kinder to bulky parcels, and some domestic road networks use 4,000.
Written out: volumetric kg = (L cm × W cm × H cm) ÷ 5,000. A box of 40 × 30 × 25 cm is 30,000 cubic centimetres, so it is charged as at least 6 kg whatever is inside it.
Three parcels, three outcomes
| Contents | Box (cm) | Actual | Volumetric | Charged |
|---|---|---|---|---|
| Two pairs of sneakers | 40 × 30 × 25 | 2.1 kg | 6.0 kg | 6.0 kg |
| A cast-iron pan | 35 × 35 × 12 | 3.8 kg | 2.94 kg | 4.0 kg |
| A winter jacket, vacuum-bagged | 35 × 25 × 10 | 1.2 kg | 1.75 kg | 2.0 kg |
| The same jacket in its retail box | 55 × 40 × 15 | 1.4 kg | 6.6 kg | 7.0 kg |
The jacket is the lesson. Nothing about the garment changed; the retail box multiplied the bill by three and a half. On the India to USA lane at ₹1,000 or more per kilogram that is the difference between a ₹2,000 and a ₹7,000 shipment.
Five changes that reduce the chargeable weight
- Remove retail packaging when the product does not need it for protection or resale. Shoes travel well in one carton with the pairs nested; the shoe boxes are the cost.
- Vacuum-bag soft goods. Clothing, bedding and soft toys lose 60 to 80% of their volume and recover when opened.
- Pick the smallest box the contents fit in with 2 to 3 cm of cushioning, not the box that happens to be in the cupboard. Carriers sell boxes in half-sizes for this reason.
- Fill voids with crumpled kraft paper rather than leaving them. Empty space does not save weight and lets the contents shift, which causes the damage claims.
- Split one very long item from a batch of small ones. A 90 cm box forced on everything else in the order is charged at 90 cm for everything.
When the carrier re-measures
Every express hub passes parcels through a dimensioning scanner that measures the three sides to the centimetre and weighs the piece at the same time. The figures on your booking are a declaration; the hub's figures are the invoice. If a box bulges, the scanner reads the bulge. If the declared weight was 3 kg and the scanner reads 3.4 kg, the bill moves to 3.5 kg and a re-weigh adjustment appears on your account a few days later. Booking with honest measurements avoids both the adjustment and the admin fee some carriers add for it.
Why the quote on our lane pages is per kilogram
The indicative rates on the ExpressBox lane pages are per chargeable kilogram for exactly this reason: the price of a parcel is its chargeable weight multiplied by the lane rate, plus duty where the destination charges it. When you request a quote, give the box dimensions as well as the weight, and we will tell you which of the two is driving the price and whether a different box would change it.
Questions we are asked
Does volumetric weight apply to documents and small packets?
In practice no. An envelope or a packet under about 25 × 20 × 5 cm has a volumetric weight below 0.5 kg, so it is always billed on actual weight at the minimum 0.5 kg band.
Do couriers round up to the whole kilogram?
Most express services round to the next 0.5 kg up to about 20 kg and to the next whole kilogram above that. A parcel measured at 2.1 kg is billed as 2.5 kg.
Is a cylinder measured as a cube?
Yes. A rolled poster tube 80 cm long and 10 cm across is measured as 80 × 10 × 10 cm, so 1.6 kg volumetric, even though the tube itself weighs 300 g.
Customs figures are those in force on the date above and are the same as on our lane pages; rates change, so confirm against your quote before paying duty.
Related: Shipping lanes and indicative rates · Request a quote · India to USA lane