Dimensional weight calculator
Enter the box size and its actual weight, then choose the divisor your carrier uses. The calculator shows the dimensional (volumetric) weight and the billable weight, the larger of the two.
Runs in your browser: nothing you enter is sent anywhere.
How to use it
- Choose metric (cm, kg) or imperial (in, lb).
- Enter the length, width and height of the packed box, measured at the widest points.
- Enter the actual weight on the scales.
- Pick the divisor, or “Other” to type your own.
- Read the dimensional weight, the billable weight and which one applies.
Dimensional weight = length × width × height ÷ divisor
- metric: cm³ ÷ (cm³ per kg) gives kg;
- imperial: in³ ÷ (in³ per lb) gives lb.
Billable weight = the larger of the actual and the dimensional weight.
Worked example
A 50 × 40 × 30 cm box weighing 8 kg: volume 60,000 cm³; with divisor 5000 the dimensional weight is 60,000 / 5,000 = 12 kg, more than the actual 8 kg, so you are billed for 12 kg. With divisor 6000 it is 10 kg.
A 20 × 16 × 12 in box weighing 18 lb: 3,840 in³ / 139 = 27.63 lb billable.
Tips
- Measure the outside of the box, including any bulges.
- Irregular items are measured by the smallest box that would contain them.
- Compare quotes: a lower rate with a smaller divisor can still cost more for bulky parcels.
Frequently asked questions
What is dimensional weight?
A weight worked out from a parcel's size: length × width × height ÷ a divisor. Carriers charge by it because a large light box takes as much space in a van or plane as a heavy one. You pay for whichever is greater, the actual or the dimensional weight.
Which divisor should I use?
It depends on the carrier and the service. 5000 cm³/kg is common for express and air services, 6000 for some road and economy services, and 139 in³/lb is common for US domestic and international express. Check your carrier's current rate guide; choose "Other" for any other value.
Do carriers round the result?
Usually yes: measurements are often rounded up to the next whole centimetre or inch, and the weight up to the next half kilogram or whole pound. The calculator shows the exact value so you can apply your carrier's rule.
How can I lower the dimensional weight?
Use the smallest box that fits, cut down tall boxes, and avoid excess padding. Volume grows fast: 5 cm less on each side of a 50 × 40 × 30 cm box cuts its dimensional weight by over a third.