Dimensional Weight Calculator: Dim Weight and Billable Weight
Parcel and air carriers charge for the greater of actual weight and the space your carton occupies. This calculator shows the dimensional weight, the billable weight and the cost, so you can see which cartons are paying for air.
Your numbers
Use the divisor in your carrier agreement. Tariffs change.
Optional, to estimate cost.
Your results
Divisors, rounding rules, minimum charges and surcharges differ by carrier and contract. Check your agreement. Air freight often uses 6,000 cubic centimetres per kilogram instead.
Billable weight vs carton height
Sweeps Height from 4 to 40, holding your other inputs fixed.
Packaging data clean-up
Optional: we can look at how carton dimensions and weights are held in your ERP item master and suggest fixes.
Optional. The tool and every export work without this. No spam.
How to use it
Enter the outside dimensions of the packed carton in inches, its actual weight in pounds and how many cartons are in the shipment. Pick the divisor from your carrier agreement. The tool divides cubic inches by the divisor, rounds up, and compares the result with actual weight rounded up. The higher number is the billable weight. Add your rate per pound to see the estimated charge.
The formula
Dimensional weight equals length times width times height divided by the divisor. A divisor of 139 means 139 cubic inches are treated as one pound. For metric air freight the common rule is length times width times height in cubic centimetres divided by 6,000 to give kilograms. A smaller divisor makes dim weight bigger, so it is worse for bulky, light cartons. The chart shows how billable weight stays flat until the carton height pushes volume above actual weight.
- Divisor 139: US domestic, inches and pounds
- Divisor 166: often used for international and some USPS rates
- 6,000 cm3 per kg: common IATA air freight convention
Worked example
A 24 by 18 by 14 inch carton is 6,048 cubic inches. With a 139 divisor, dim weight is 43.5 pounds, rounded up to 44. The actual weight is 22 pounds, so the carton bills at 44 pounds. Ten cartons bill at 440 pounds. Cutting the height to 10 inches drops dim weight to 32, and a smaller box with less void fill could save about a quarter of the freight cost.
Common mistakes
Using product size instead of the outer carton size, ignoring bulging, and rounding down all understate the bill. Many carriers apply dimensional weight per package, not per shipment, and round each dimension to the nearest inch first. Keep standard carton sizes in your item master and store dimensions with the packaging code so ERP shipping and carrier systems agree.
Frequently Asked Questions
What is the difference between dimensional and billable weight?
Dimensional weight is a volume-based figure calculated from carton size and a carrier divisor. Billable weight, also called chargeable weight, is the greater of dimensional weight and actual weight. The carrier prices the shipment on billable weight, so light but bulky cartons often pay for space rather than mass.
Which divisor should I use?
Use the one in your carrier contract or published service guide. Common values are 139 for US domestic inches and pounds, 166 for some international and USPS services, and 6,000 cubic centimetres per kilogram for air freight. Carriers revise these, so do not rely on a number from last year.
Does dimensional weight apply to LTL freight?
Not in the same way. US LTL rating uses freight class driven by density, although some carriers apply minimum charges or cubic capacity rules. Use the freight class density calculator for LTL pallets, and this tool for parcel, express and air freight.
How can I lower my dimensional weight charges?
Right-size cartons, reduce void fill, use poly mailers where product allows, and ship multiple units in one larger carton when the bundle is denser. Compare your carton library against actual product dimensions. A small change in height often moves billable weight more than a change in length.
If cartons are rated by hand from spreadsheets, Netray can help connect item master packaging data to rate shopping and freight accrual.
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