Dimensional Weight Calculator
Enter the length, width and height of your package, its actual weight and your carrier divisor. The calculator shows the dimensional weight and the billable weight carriers use to set the price.
How to use this Dimensional Weight Calculator
- Measure the longest side, then the width and the height of the packed box, in inches.
- Weigh the packed box in pounds.
- Enter the divisor your carrier uses. It is in the carrier rate guide.
- Press Calculate to see the dimensional weight and the billable weight.
- If the dimensional weight is higher, try a smaller box to cut your shipping cost.
How to calculate dimensional weight
Carriers charge on the larger of the actual weight and the dimensional weight, because a big light box takes space.
- Volume = length x width x height (inches)
- Dimensional weight = volume / divisor
- Billable weight = the larger of dimensional weight and actual weight, rounded up to the next pound
Worked example
A packed box is 16 in by 12 in by 8 in, so the volume is 1,536 cubic inches. With a divisor of 139 the dimensional weight is 1,536 / 139 = 11.05 lb. The box weighs 5 lb, so the dimensional weight is higher and the billable weight is 12 lb after rounding up.
If you used a box that is 12 in by 10 in by 6 in, the volume would be 720 cubic inches and the dimensional weight 5.18 lb, so the billable weight would be 6 lb. A smaller box saves you 6 lb of billable weight, and that can mean a much lower label price. Check your carrier price chart for the difference.
Assumptions & limits
- The divisor is an editable input. Carriers use different divisors for different services, and they can change them. Check your carrier rate guide instead of relying on the default.
- Many carriers round dimensions up to whole inches and weight up to whole pounds. This calculator rounds only the billable weight.
- Some services apply dimensional weight only above a size threshold, and some do not use it at all.
- The calculator does not price the shipment. It only finds the billable weight.
- Dimensions are for the packed box, not the product. Last reviewed November 5, 2026.
Frequently asked questions
What is dimensional weight?
It is a weight calculated from the size of a package, used by carriers when a package is large and light.
How do I calculate dimensional weight?
Multiply length by width by height in inches and divide by the carrier divisor. 1,536 divided by 139 is 11.05 lb.
What is a DIM divisor?
It is the number carriers divide the volume by. A smaller divisor gives a higher dimensional weight.
Which weight do carriers charge for?
They charge on the larger of the actual and the dimensional weight.
How can I reduce dimensional weight?
Use a smaller box, remove empty space or use a poly mailer for soft goods.
Do all carriers use dimensional weight?
Many do for at least some services, but the rules differ. Check your carrier.
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Last updated: November 2026