How to Calculate Volumetric Weight for Courier and Cargo
By BizToolsIndia Editorial Team · Updated · Logistics & Shipping Calculators
Quick answer
Multiply the box's length × width × height in centimetres and divide by the carrier's divisor — usually 5000 for couriers or 6000 for air cargo. A 40 × 30 × 25 cm box is 30,000 cm³ ÷ 5,000 = 6 kg. The carrier bills the higher of this and the actual weight.
Skip the maths — use the Volumetric Weight Calculator →
Step by step
- Measure the packed box's outer length, width and height in centimetres. Measure at the widest point, including bulges.
- Multiply them to get the volume in cubic centimetres (cm³).
- Divide by your carrier's divisor to get volumetric weight in kilograms.
- Weigh the box. The chargeable weight is the higher of the two.
- Round up to the carrier's weight slab (often 0.5 kg).
Volumetric weight (kg) = L × W × H (cm) ÷ Divisor
Working in inches
Convert each dimension to centimetres first (× 2.54). A 16 × 12 × 10 inch box is 40.64 × 30.48 × 25.4 cm = 31,463 cm³, which is 6.29 kg at a divisor of 5000.
Examples: the same weight, different bills
| Box (cm) | Actual weight | Volumetric weight | Chargeable |
|---|---|---|---|
| 30 × 20 × 15 | 4 kg | 1.8 kg | 4 kg (actual) |
| 50 × 40 × 30 | 4 kg | 12 kg | 12 kg (volumetric) |
| 60 × 50 × 40 | 4 kg | 24 kg | 24 kg (volumetric) |
The larger boxes cost three to six times as much to ship even though they weigh the same.
Ways to lower your chargeable weight
- Keep a few box sizes in stock so each product ships in a snug carton.
- Replace oversized boxes plus fillers with right-sized boxes or padded mailers for small items.
- Compare carriers — a 6000 divisor gives 17% less volumetric weight than 5000 for the same box.
Divisors by mode of transport
| Mode | Common rule | What it means |
|---|---|---|
| Domestic express courier | L × W × H (cm) ÷ 5,000 | 1 m³ = 200 kg |
| Air cargo (IATA) | L × W × H (cm) ÷ 6,000 | 1 m³ ≈ 167 kg |
| Some courier services | L × W × H (cm) ÷ 4,000 | 1 m³ = 250 kg — check your contract |
| Sea freight (LCL) | 1 CBM = 1,000 kg | Charged per CBM or per tonne, whichever is higher |
Road and surface carriers use a variety of conversions, sometimes based on cubic feet. The divisor and rounding slab on your rate card are what count.
Worked examples
| Box (cm) | Volume | ÷ 5,000 | ÷ 6,000 |
|---|---|---|---|
| 20 × 15 × 10 | 3,000 cm³ | 0.6 kg | 0.5 kg |
| 45 × 35 × 30 | 47,250 cm³ | 9.45 kg | 7.875 kg |
| 100 × 80 × 60 | 4,80,000 cm³ | 96 kg | 80 kg |
For a shipment of several identical boxes, multiply the per-box figure by the number of boxes: ten 50 × 40 × 40 cm cartons are 16 kg each at 5,000, so 160 kg in total (0.8 CBM).
Pallets and CBM
Freight is often quoted by volume in cubic metres (CBM). A pallet 120 × 100 cm stacked to 150 cm high is 1.2 × 1.0 × 1.5 = 1.8 CBM. By air at a 6,000 divisor, that is 300 kg of volumetric weight — so a pallet weighing 250 kg would be charged as 300 kg. The Freight Calculator prices shipments by weight, volume or trip.
CBM = Length (m) × Width (m) × Height (m)
= L × W × H (cm) ÷ 10,00,000
Measuring correctly
- Measure the parcel after packing, at the longest point on each side, including bulges and handles.
- Round each dimension up to the next whole centimetre, as most carriers do.
- For irregular items, measure the smallest box that would enclose them.
- Photograph the parcel with a tape measure in view if you ship bulky items often — it helps with weight disputes.
How carriers round
Most courier rate cards bill in slabs, often 0.5 kg. A chargeable weight of 2.1 kg becomes 2.5 kg; 2.5 kg stays 2.5 kg. That makes small size reductions valuable when they cross a slab boundary. For seven practical ways to do that, read packing changes that cut courier charges.
From chargeable weight to the final bill
Volumetric weight decides the billed weight, but the invoice has more lines. Here is an illustrative example — use your own courier's rate card for real figures.
| Step | Amount |
|---|---|
| Chargeable weight (higher of the two) | 3.2 kg |
| Billed weight (rounded up to 0.5 kg) | 3.5 kg |
| Freight: ₹50 + 6 × ₹40 | ₹290.00 |
| + Fuel surcharge 10% | ₹29.00 |
| Subtotal | ₹319.00 |
| + GST 18% | ₹57.42 |
| Total | ₹376.42 |
Cash-on-delivery fees, return (RTO) charges and remote-area surcharges can be added on top. The Courier Shipping Cost Calculator builds the full estimate from your own rates.
Worked example: an air cargo shipment
An exporter sends five cartons, each 60 × 40 × 40 cm and weighing 12 kg, by air. The airline uses the IATA divisor of 6,000.
- Volume per carton = 60 × 40 × 40 = 96,000 cm³ (0.096 CBM).
- Volumetric weight per carton = 96,000 ÷ 6,000 = 16 kg.
- Shipment volumetric weight = 5 × 16 = 80 kg; total volume 0.48 CBM.
- Actual weight = 5 × 12 = 60 kg.
- Chargeable weight = the higher figure, 80 kg.
Packing the same goods into cartons 5 cm shorter on each side would bring the volumetric weight close to the actual weight — a quarter less freight to pay.
Checking a weight discrepancy
Couriers re-measure parcels at their hubs and may bill a higher weight than you declared. When that happens, compare their dimensions with yours, recalculate the volumetric weight with their divisor, and check the rounding. If your photos show smaller dimensions, raise a dispute within the courier's deadline. Repeated discrepancies usually mean the packed box is larger than the size you record — measure after packing, not before.
Frequently asked questions
Why do different couriers give different volumetric weights?
They use different divisors and rounding rules. Check the divisor and rounding slab on each rate card.
Is volumetric weight the same as CBM?
No. CBM is volume in cubic metres, used for freight and container loads. Volumetric weight converts volume into a billable weight using a divisor.
Do all couriers charge volumetric weight?
Almost all express couriers and airlines do, above a minimum size. The divisor and rounding vary, so check each rate card.
Does volumetric weight apply to documents?
Envelopes and flat document packets are usually billed on actual weight because their volume is negligible.
How do I convert CBM to volumetric weight?
Multiply CBM by 1,000,000 to get cm³, then divide by the divisor. At 5,000, 1 CBM = 200 kg; at 6,000, 1 CBM ≈ 166.67 kg.
Is GST charged on courier charges?
Yes. Courier services are generally taxed at 18% GST, which registered businesses can usually claim as input tax credit.
Are multi-box shipments charged per box or in total?
It depends on the carrier and service. Many express couriers calculate chargeable weight per piece, while cargo shipments are often assessed on the total. Check your rate card.
Can I negotiate the volumetric divisor?
Businesses shipping regular volumes can often negotiate rates, slabs and sometimes the divisor with couriers or aggregators. Compare the effective cost on your typical box sizes, not just the headline rate.
What happens if actual and volumetric weight are the same?
Then either figure is the chargeable weight. It still gets rounded up to the courier's slab, so a parcel of exactly 2.5 kg is billed at 2.5 kg, while 2.51 kg is usually billed at 3 kg.