How to use
- Choose cm · kg or inch · lb, then enter the box’s length, width, height and actual weight.
- Pick the divisor your carrier quotes, or choose Custom and type it in.
- The chargeable weight — the higher of actual and volumetric weight — appears instantly. If your carrier bills in 0.5 kg or 1 lb increments, turn on rounding.
The formula
Light but bulky parcels take up space that could carry heavier cargo, so air freight and express services compare the actual weight with a volumetric weight derived from size, and bill whichever is higher.
| Item | Formula |
|---|---|
| Volumetric weight (cm, kg) | L × W × H (cm) ÷ divisor |
| Volumetric weight (in, lb) | L × W × H (in) ÷ divisor |
| Chargeable weight | max(actual weight, volumetric weight) |
| Divisor | Unit | Notes |
|---|---|---|
| 6000 | cm³/kg | IATA standard for air cargo; 1 CBM ≈ 166.67 kg |
| 5000 | cm³/kg | Common for international express; 1 CBM = 200 kg |
| 166 | in³/lb | 6000 cm³/kg expressed in inches and pounds (≈ 166.08) |
| 139 | in³/lb | Close to 5000 cm³/kg (the exact conversion is ≈ 138.4) |
A smaller divisor produces a higher volumetric weight, and therefore a higher bill.
Example
A 20 × 15 × 10 in box (3,000 in³) weighing 15 lb:
| Divisor | Volumetric weight | Chargeable weight |
|---|---|---|
| 139 | 3,000 ÷ 139 ≈ 21.58 lb | 21.58 lb, or 22 lb rounded up |
| 166 | 3,000 ÷ 166 ≈ 18.07 lb | 18.07 lb, or 19 lb rounded up |
In metric, a 50 × 40 × 30 cm box (60,000 cm³) is 12 kg volumetric at 5000 and 10 kg at 6000. If it actually weighed 15 kg, you’d be billed for 15 kg either way.
Things to keep in mind
- Divisors vary by carrier, service and contract, and they change. This tool applies the formula only — confirm the divisor and rounding rules with your carrier before relying on a quote.
- Measure the packed box at its widest points. Carriers also differ in how they round fractional dimensions.
- For multi-piece shipments, carriers may sum per-box volumetric weights or calculate on the total; check their rules.
- Ocean freight uses cubic meters and revenue tons instead — see the CBM calculator.
FAQ
Is volumetric weight the same as dimensional (DIM) weight?
Yes. Volumetric weight, dimensional weight and DIM weight all describe the same calculation.
Why am I billed for more than my parcel weighs?
Because its volumetric weight is higher than its actual weight. A smaller box helps: moving the same item from 50 × 40 × 30 cm to 45 × 35 × 25 cm drops the volumetric weight at 5000 from 12 kg to 7.875 kg.
Which divisor should I use?
Whatever your carrier and service specify. It can differ between services from the same company and between negotiated contracts.