Where each of these calculators stops being right
A calculator that tells you where it stops being right is more useful than one that doesn't, because the place it stops is usually where your money is. Here is each tool on this site, what it assumes, and the case that breaks it.
Import duty — assumes an ad valorem rate and one taxable base
The duty calculator applies a percentage to a value and then a VAT percentage to value + duty + fees. That is the common shape and it is not the only one.
- Specific and compound duties. Some goods are charged per kilo, per litre, per pair, or by a percentage and a fixed amount. A percentage-only tool cannot express those at all.
- The taxable base varies. Which clearance charges sit inside the VAT base is a national rule. Put the wrong fees in and the VAT line moves.
- Preferential rates and trade remedies. A free trade agreement can take the rate to zero with the right origin documentation; anti-dumping or countervailing duty can add tens of percent. Neither is in the tool, and both dwarf everything else on this page when they apply.
Customs value — assumes the transaction value, and only that
The customs value calculator adds freight and insurance to the invoice according to the Incoterm. Real valuation rules add more things to the price actually paid:
- Assists — tooling, moulds, dies, materials or design work you supplied to the manufacturer free or cheap.
- Royalties and licence fees you pay as a condition of sale.
- Proceeds of resale that go back to the seller.
- Related-party pricing, where the transaction value may be rejected outright in favour of another valuation method.
These are not rounding errors. A 1,500.00 tooling assist on the shipment above raises the dutiable value from 22,580.00 to 24,080.00 and the total bill by 1,917.00.
Landed cost — leaves VAT out, and leaves time out
The landed cost calculator has no VAT field because a VAT-registered importer usually recovers import VAT, so including it would overstate the cost of goods. If you cannot recover it, add it in as a fee. It also has no line for demurrage, storage, detention, currency hedging, finance cost on the time between paying and selling, or the cost of the units that arrive broken — all of which are real and none of which are predictable enough to model.
Volumetric weight — the divisor is the carrier's, not ours
The volumetric weight calculator defaults are conventions, not rules. Your carrier's contract specifies the divisor, and some also round each piece up to the next 0.5 or 1.0 kg before charging, which this tool does not. Use the number in your rate agreement, not the number that sounds familiar.
Container load — pure volume, and nothing else
The container load calculator divides internal volume by carton volume. It knows nothing about payload limits, pallet footprints, whether your carton dimensions divide into the container's, or bracing. Dense cargo hits the weight ceiling long before the volume ceiling and the tool will happily tell you otherwise.
And one we got wrong
Until recently this calculator rounded the carton volume to two decimal places before dividing by it. For a 0.096 m³ carton that understated capacity by 4%; for a 20 cm cube (0.008 m³), by 20%; and any carton below 0.005 m³ rounded to zero, at which point the tool reported that no cartons fit and no containers were needed. A 15 cm cube — 9,837 of which genuinely fit a 20ft — returned zero.
It is fixed, and the volume is now kept exact for the division and rounded only for display. If you used this page with a small carton and got an answer that looked absurd, it was, and it was ours.
The short version
| Calculator | Assumes | Breaks when |
|---|---|---|
| Import duty | A single ad valorem rate, one taxable base | Duties are specific or compound, or a trade remedy applies |
| Customs value | The transaction value, adjusted only for freight and insurance | There are assists, royalties, or a related seller |
| Landed cost | Import VAT is recoverable, so it is not a cost | You cannot reclaim it, or the goods sit in storage |
| Volumetric weight | The divisor you type is the one you are billed on | The carrier also rounds each piece up |
| Container load | Cargo fills a container like a liquid | It is palletised, dense, or oddly shaped — which is most cargo |
| Currency converter | The rate you enter is the rate that applies | Customs converts at its own published rate instead |
What none of them replace
All six are estimators. They tell you the shape of a bill and which question matters most, which is enough to choose a supplier, size a container or challenge a freight quote. They are not a customs assessment and they cannot be — the binding answer depends on your goods' classification, their origin, your jurisdiction's rules and the specific transaction. For that, a licensed customs broker or your national customs authority is the only source that counts.
Work it for your own shipment
The figures above come from the same code the calculators run, so typing these inputs in reproduces them exactly. Your own numbers are the point though — all six calculators are here.
These are estimates, not assessments. Duty rates, the taxable base, and the valuation rules that decide them are set by national law and by how your goods are classified. A customs broker or your national customs authority gives you the binding answer; this site gives you the arithmetic so you know roughly what is coming and which question to ask.