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Dimensional Weight Calculator: Find Your Billable Shipping Weight

Enter your box dimensions, actual weight and carrier divisor to see whether you'll be billed by size or by scale weight, in imperial or metric units.

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Billable weight
7 lb

Dimensional weight applies. You will likely be billed for 7 lb, not your actual 5 lb, because the box takes up more space than it weighs.

Volume
960 in³
Dimensional weight
7 lb
Actual weight (rounded up)
5 lb

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What dimensional weight is

Carriers do not just charge by how heavy a box is. A large, light box like a lampshade or a stack of pool floats takes up truck and plane space that a dense, heavy box of the same weight would not, so most carriers bill by whichever number is bigger: the actual weight or a calculated dimensional weight based on the box's volume. That second number is what this calculator works out. Get it wrong when you are quoting shipping to a customer and you eat the difference out of your margin on every order.

The formula

Dimensional weight equals length times width times height, divided by a divisor set by the carrier and the service level. In inches and pounds, 139 is the common domestic divisor used by UPS, FedEx and USPS for most ground and air services, while 166 shows up on some international air services. In centimeters and kilograms, 5000 is the standard international divisor, with 6000 used by some carriers on certain lanes. Whichever number you get, it is standard practice to round it up to the next whole unit, and the billable weight is the larger of that rounded dimensional weight and your rounded actual weight.

Checking your divisor

Divisors are not universal. They vary by carrier, by service tier within the same carrier, and sometimes by shipping lane, and carriers update them from time to time. This tool defaults to the common 139 and 5000 figures, but treat those as a starting estimate and confirm the exact divisor on your own carrier account or rate agreement before you rely on the number for pricing decisions or a shipping calculator on your own site.

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FAQ

Dimensional Weight Calculator: questions, answered

What is dimensional weight and why do carriers use it?
It is a weight figure calculated from a package's volume instead of a scale, used so carriers can charge fairly for space rather than just mass. A box of pillows can fill a truck without weighing much, so carriers bill the larger of the actual weight and this calculated figure to account for the space it actually occupies.
Which divisor should I use?
It depends on your carrier and service level. Domestic US shipments commonly use 139 for inches and pounds, while international air shipments often use 5000 for centimeters and kilograms, or sometimes 166 and 6000 respectively on certain services. Check your specific carrier rate agreement, since these figures do get revised and vary by account.
What if my dimensional weight is lower than actual weight?
Then your actual weight is what gets billed, since carriers charge the larger of the two figures. Dense, compact items like books or metal parts usually fall into this category, where the physical weight, not the box size, drives the shipping cost.
Do I need to round up?
Most carriers round both the dimensional weight and the actual weight up to the next whole pound or kilogram before comparing them and billing. This calculator does that rounding automatically so the figures match what you would typically see on an actual shipping invoice.
Does this apply to international shipments?
Yes, and it is often more aggressive internationally. Many international air services use a 5000 cm/kg divisor, which produces a higher dimensional weight than the 139 in/lb domestic formula for an equivalent box, so large, light packages tend to cost noticeably more to ship internationally than the actual weight alone would suggest.

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