Volumetric weight is what actually gets billed
Air freight prices space, not mass. Every carrier calculates a volumetric weight from your box dimensions — length × width × height in centimetres, divided by 6000 — and bills whichever is higher, that or the actual weight on the scale.
The arithmetic catches people out constantly. Four pairs of sneakers in their original boxes fill roughly 40×30×20cm. That is 24,000 cubic centimetres, which divided by 6000 gives 4kg volumetric. The parcel itself might weigh 1.8kg. You pay for 4kg. More than half of what you are shipping is air inside cardboard.
Which line to pick
The lines fall into three groups, and the right choice depends more on what is in the box than on how patient you are.
Economy and tax-paid lines — 15 to 35 days
Cheapest per kilo and the default for most hauls. EU-bound tax-paid lines matter more than the price difference suggests: they clear customs with duty already settled, so nothing gets held and no handling fee appears at the door. On a UK or EU route this usually beats a nominally cheaper line that leaves you settling VAT plus a courier's clearance charge on delivery.
EMS and standard post — 10 to 18 days
The middle option. Hands off to your national postal service on arrival, which means delivery to a residential address without a courier depot detour. Reliable, rarely the cheapest.
DHL, FedEx and UPS — 5 to 10 days
Roughly double the economy price. Worth it for something time-sensitive or high-value, since tracking is genuinely granular and claims actually get paid. Note that express carriers present duties for payment far more consistently than postal lines do — factor that into the comparison rather than treating the freight quote as the total.
Duties, and the thresholds that matter
Freight is one number, import charges are another, and the second one surprises more buyers than the first.
- United States — the de minimis exemption for low-value parcels has been progressively narrowed, and the treatment of China-origin shipments in particular has changed more than once in the last two years. Check the current position before assuming a small parcel clears free.
- European Union — VAT applies from the first cent; there is no low-value exemption. Duty is charged above €150. An IOSS-registered line collects the VAT up front, which is why tax-paid lines are worth their premium.
- United Kingdom — VAT from £0, duty above £135.
- Australia — GST applies from the first dollar on imported goods.
Consolidation, and when it stops paying
Every agent lets you hold items in a warehouse and ship them together. The saving is real — you pay one first-weight charge instead of five — but it is not unlimited, because the first-weight premium is a fixed cost and per-kilo rates are roughly linear after it.
In practice, consolidating two or three small orders is clearly worth it. Beyond about 8–10kg you are mostly just paying per kilo, and the marginal saving from adding a fifth item is small compared to the risk of sitting on stock for another three weeks. Free storage windows run 60 to 100 days depending on the agent, so there is no urgency — but there is a point where waiting stops buying you anything.
The fee calculator lists the free-storage window alongside the fee for each agent, since the two decisions interact.