Dimensional weight and billable weight calculator
Enter the consignment and its real weight. You get the dimensional weight, the billable weight the carrier will charge, and the full arithmetic — including the rounding rule that is the usual reason a calculator and an invoice disagree, and the loading metre rule that catches out anyone buying road groupage.
What billable weight actually is
A carrier's cost is driven by the space a consignment occupies, not by its mass. A pallet of polystyrene and a pallet of bolts take the same slot on the trailer, so charging both by weight would mean losing money on the polystyrene. The trade's fix is to convert volume into a notional weight and bill whichever is higher. That higher figure is the billable weight, and it is the only number that reaches the invoice.
The conversion is one division:
dimensional weight = (length × width × height) ÷ divisor
or, in the form the freight side uses:
dimensional weight = cubic metres × kg per m³
They are the same thing. A 5,000 divisor is 200 kg per cubic metre; a 333 kg/m³ ratio is a 3,000 divisor. Parcel carriers speak in divisors and freight forwarders speak in kg/m³, for no better reason than habit.
Divisors and ratios in use
| Basis | Divisor | Equivalent | Where you meet it |
|---|---|---|---|
| Parcel, imperial | 139 in³/lb | — | FedEx all services, UPS daily rates, DHL Express US |
| Parcel, imperial retail | 166 in³/lb | — | UPS counter rates, USPS Priority Mail over 1 ft³ |
| Parcel, metric | 5,000 cm³/kg | 200 kg/m³ | DHL Express Worldwide, UPS and FedEx international |
| Parcel, metric express | 6,000 cm³/kg | 167 kg/m³ | Most European domestic express services |
| Road groupage | 3,000 cm³/kg | 333 kg/m³ | UK–Europe and intra-European groupage |
| Air freight IATA | 6,000 cm³/kg | 167 kg/m³ | International standard, near universal |
| Sea LCL | 1,000 cm³/kg | 1,000 kg/m³ | Billed per tonne or cubic metre, whichever is greater |
The loading metre, the rule almost nobody calculates
All of the above assumes something can be loaded on top of your freight. When it cannot — because it travels in a cage, because it is fragile, because it exceeds about 120 cm in height, or simply because the packaging forbids it — the calculation changes entirely. The carrier loses all the vertical space above your consignment and charges for it in loading metres of deck:
loading metres = (length × width in metres) ÷ usable vehicle width
billable weight = loading metres × 1,750 kg
Usable width is around 2.45 m in a European curtainsider and 2.35 m in a container. The 1,750 kg per loading metre figure is the common domestic one; international usually rises to 1,800. Both are set by your contract, not by law.
Since 18 August 2025 UPS and FedEx round every fractional dimension up to the next whole inch before the formula runs. A 12.1 in side is billed as 13 in. On a mid-size carton that single step can add several pounds of billable weight, and it is the most common reason a hand calculation comes out lower than the invoice.
When freight cannot be stacked, the carrier does not charge you for the volume it occupies: it charges for the floor you block, because nobody can load anything on top. A non-stackable 120 × 80 cm pallet takes 0.39 loading metres, and at 1,750 kg per metre that is 686 kg billable even if the pallet weighs 180. Quoting that consignment on actual weight is wrong by almost four times, and it is the most common argument with a forwarder.
UPS applies 139 on daily rates and 166 at the counter. DHL uses 5,000 on Express Worldwide and 4,000 on Express Domestic in some markets. Same box, same company, and up to a quarter difference in billed weight depending on the service booked. It is worth checking which service you are actually being rated on.
A worked example
A carton of 18.4 × 14 × 12.2 inches holding 9 lb, shipped on UPS daily rates.
- Round each dimension up to the next whole inch: 19 × 14 × 13.
- Volume: 19 × 14 × 13 = 3,458 in³.
- Divide by 139: 3,458 ÷ 139 = 24.88, rounded up to 25 lb.
- Against the 9 lb actual weight, the higher figure wins, so you are billed for 25 lb — nearly three times the real weight.
Without the rounding step the answer would have been 22.6 lb, rounded to 23. Two pounds of billable weight appear purely from the rounding rule. Multiply that across a few hundred shipments a month and it stops being trivia.
Now the same freight on a trailer
A 120 × 80 × 150 cm pallet weighing 180 kg, moving as road groupage:
- Volume: 1.20 × 0.80 × 1.50 = 1.44 m³. At 333 kg/m³ that is 480 kg, well above the 180 kg actual weight.
- Make it non-stackable and the basis changes: floor area 0.96 m² ÷ 2.45 m width = 0.392 loading metres, × 1,750 = 686 kg.
Same pallet, same goods, same trailer: 180 kg on the scale, 480 by volume, 686 if it cannot be stacked. A budget built on the 180 lands at about a quarter of the invoice, and that gap comes out of somebody's margin.
Where this calculator stops being accurate
- It rates one consignment, not one invoice. Fuel, residential, additional-handling, delivery-area and peak-season surcharges are all applied after billable weight is set. This figure is an input to your rate, not the rate.
- Your contract beats any published figure. Larger shippers negotiate their own divisor. Use the custom option with the number on your own agreement, which will be in the rate schedule rather than the tariff.
- Minimum billable weights are not modelled. Almost every carrier has a minimum per consignment or per piece. A small shipment can be billed at that minimum even when the calculation gives less.
- Carriers measure the extremes. They measure the finished piece including shrink wrap, corner boards and any bulge. Measuring from the carton supplier's flat spec consistently understates the billable weight.
- Loading metre practice varies. Some operators bill by half-deck or by pallet space rather than exact loading metres, and some round up to the next tenth. Check which yours uses.
- Divisors change. They move with annual rate updates, usually announced late in the year. The figures here were checked on the date at the foot of the page.
Questions people actually ask
Why is my invoice higher than this calculator says?
In order of likelihood: the piece was measured differently — carriers measure the finished consignment including any bulge, and a wrapped pallet is never as square as its plan; the fractional-inch rounding was applied and you did not apply it; the freight was classified as non-stackable and rated on loading metres; or a minimum billable weight kicked in. All four are arguable with evidence, and all four are far easier to win if you measured and photographed the consignment before it left.
Does dimensional weight apply to every shipment?
For UPS, FedEx and DHL, yes — all packages, all services. USPS is the exception: Priority Mail applies it only above 1 cubic foot, so most small parcels are rated on actual weight alone. That threshold is why a slightly smaller box can occasionally produce a much cheaper USPS rate.
How do I know whether my freight counts as stackable?
The carrier decides at loading, not you at quoting, which is exactly why it is worth agreeing in writing. In practice anything above about 120 cm in height, anything in a cage or stillage, anything marked fragile, and any piece whose packaging will not guarantee it can carry a load on top gets classified as non-stackable. If yours is stackable and you want it rated that way, state it on the paperwork and make sure the packaging supports it.
What divisor should I aim for when negotiating?
The published figures are 139 for contract accounts and 166 at retail, so any negotiated divisor above 139 improves on the standard tariff. Whether it is achievable depends on your volume and your mix — a shipper of light bulky goods has far more to gain from a divisor concession than from a headline discount percentage, and it is worth asking for the divisor specifically.
Is sea freight calculated the same way?
Same principle, very different ratio: 1,000 kg per cubic metre, one tonne per m³. It is billed per w/m, meaning by tonnes or cubic metres, whichever is greater. Because the ratio is so high, almost all industrial freight bills by volume rather than weight at sea — the opposite of what happens on the road.
Does the calculator send my figures anywhere?
No. The arithmetic runs in your browser and nothing is transmitted or stored. You can disconnect from the network and the tool still works. That is deliberate: the dimensions and volumes of a consignment say a good deal about a business.
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