"It weighs 2 kg — why was I billed for 5?" Dimensional weight, explained and calculated
How to use
- Enter the box's length, width and height. If the product page lists inches, switch the unit to inch and the calculator converts to centimetres for you.
- Add the actual weight in kg or lb. Leave it blank if you don't know yet — you still get the volumetric weight, and you can come back once your forwarder reports the scale weight.
- Pick the DIM divisor. Express carriers and most package forwarders use 5000; some routes use 6000. Use whatever number appears on your carrier's rate page.
- Shipping several identical boxes? Raise the box count to see per-box and total figures.
- The chargeable weight is what you'll be billed on. Enter a per-kg rate to estimate the cost, then copy the result.
What volumetric weight is
Aircraft run out of space long before they run out of lifting capacity. A box of foam weighs almost nothing but takes up the room of a 20 kg parcel, so carriers convert volume into an equivalent weight and charge whichever is higher. The formula is simple:
| Volumetric weight (kg) | L × W × H in cm ÷ divisor (5000 or 6000) |
|---|---|
| In inches and pounds | L × W × H in inches ÷ 139 = volumetric weight in lb (close to the ÷ 5000 metric figure) |
| Chargeable weight | The greater of volumetric and actual weight |
| Example | 40 × 30 × 20 cm = 24,000 ÷ 5000 = 4.8 kg. A 2 kg item in that box is billed as 4.8 kg |
5000 versus 6000
A divisor of 6000 makes the same box about 17% "lighter". The 40 × 30 × 20 cm box above is 4.8 kg at 5000 but 4.0 kg at 6000. International express carriers traditionally use 5000; freight forwarders and consolidators vary by route and partner airline. When comparing forwarders, look at the divisor as well as the per-kg rate — a larger divisor favours bulky, light goods.
How to reduce it
| Repacking | Retailers often ship small items in oversized boxes full of air. Most forwarders offer a repack service that swaps in a snug box. |
|---|---|
| Remove shoe boxes | Shoe boxes are mostly air; volumetric weight can be two or three times the actual weight. Skip this if you need the box for resale or gifting. |
| Consolidate | Combining several orders into one shipment fills empty space and lowers the per-kg cost, though it may push the declared value over your country's duty-free threshold. |
| Compress | Vacuum bags for jackets and bedding, flat-pack for furniture. |
CBM and sea freight
The result also shows CBM (cubic metres), the unit used for ocean freight. A 40 × 30 × 20 cm box is 0.024 CBM. Less-than-container (LCL) sea shipping is often priced per CBM rather than per kg, which makes it far cheaper for bulky furniture or large orders — at the cost of three to six weeks in transit.
FAQ
The store doesn't list the package size
Look for "Package Dimensions" or "Shipping Weight" on the product page, check reviews, or wait for your forwarder's inbound notice, which usually includes measured dimensions. The preset buttons give rough figures for typical boxes.
Do I pay for both weights?
No — only the greater of the two. Light, bulky parcels are billed on volume; small, dense ones on the scale weight.
I don't know the divisor
Use 5000. It's the default for express air and most forwarders; if yours uses 6000, the real bill will be slightly lower than the estimate.
Related tools
- Currency converter — turn a dollar shipping quote into your currency
- Shoe & clothing size converter — check sizes before you order abroad
- Unit converter — inches and pounds to centimetres and kilograms