Dimensional Weight Calculator
Find the dimensional (volumetric) weight of a shipping box and the billable weight carriers actually charge you for.
How it works
Dimensional weight = (L × W × H) ÷ DIM divisor · Billable weight = greater of dimensional and actual weight
Carriers charge by whichever is larger — the real weight or a “dimensional weight” that reflects how much truck or plane space a package occupies. Dimensional weight is the box volume divided by a published divisor: about 139 for US domestic shipments measured in inches and pounds, or 5000 for international shipments in centimetres and kilograms. Light but bulky items (pillows, lampshades) are almost always billed on dimensional weight.
Worked example
A 12 × 10 × 8 in box is 960 in³. Dividing by 139 gives a dimensional weight of 6.91 lb. If the box actually weighs 3 lb, you are billed on the larger figure — 6.91 lb.
Frequently asked questions
Why am I charged more than my package weighs?
Because a large, light box takes up space that could carry heavier freight. Dimensional weight pricing lets carriers charge for that volume, so a bulky 3 lb parcel can bill like a 7 lb one.
How do I lower the dimensional weight?
Use the smallest box that safely fits the contents and trim empty space. Every inch removed cuts the volume — and therefore the dimensional weight — noticeably, since volume grows with all three dimensions.
Which divisor should I use?
It depends on the carrier and service: US domestic ground is commonly 139 (inches, pounds), while many international services use 5000 (centimetres, kilograms). Check your carrier’s current rate card and enter that number.
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This calculator is for educational purposes. Double-check important results before acting on them.