Dimensional Weight Calculator
A light box can still be a heavy shipment.
Dimensional Weight Calculator
Work out the billed weight of a parcel from its carton size and the carrier divisor.
UPS and FedEx use 139 for daily rates. Retail counter rates use 166.
Weigh the packed carton, not the product alone.
Carriers bill the greater of actual weight and dimensional weight. A large, light carton is priced by the space it occupies, so shrinking the box is often cheaper than finding a lighter product.
Embed this calculator
Put this calculator on your own site with the snippet below. The frame contains the tool only, reports its own height, and carries a visible link back to the full page. Embedding is free; keep the attribution link as it is, and do not wrap the frame in a way that hides it.
Preparing the embed code for this page...
What This Calculator Does
The Dimensional Weight Calculator works out what a parcel is billed at when its size, rather than its scale weight, decides the price. Enter the carton dimensions, the actual weight, and the carrier divisor, and it returns the dimensional weight, the billable weight, and how far the parcel is above its actual weight.
How It Works
Carton volume is length x width x height in the carrier unit. Dividing volume by the carrier divisor gives dimensional weight in pounds or kilograms. The billable weight is the greater of that figure and the actual weight. A parcel whose dimensional weight exceeds its actual weight is described as being billed by dimension, and the difference is the weight it is effectively paying for but does not weigh.
Example
A carton measuring 20 x 16 x 12 inches has a volume of 3,840 cubic inches. Under the UPS and FedEx daily-rate divisor of 139, its dimensional weight is 3,840 / 139 = 27.6 lb. A 10 lb parcel is therefore billed at 27.6 lb, about 176% above its actual weight. The same carton under the 166 retail divisor is 23.1 lb.
Formula
length x width x heightvolume / carrier divisormax(actual weight, dimensional weight)(billable weight - actual weight) / actual weight x 100Shown only when actual weight is above zero.
Reading the Results
Billable weight
The weight the carrier prices. It is the greater of the dimensional and actual figures, before any rounding up to the next whole pound or kilogram.
Dimensional weight
The hypothetical weight of the space the carton occupies. It is a billing convention, not a physical property of the parcel.
Over actual weight
How much larger the billable weight is than the scale weight. A high percentage means the packaging, not the product, is driving the shipping cost.
Sources and References
UPS - Dimensional Weight
Daily-rate and retail divisors for parcel billing
UPS publishes 139 for daily rates and 166 for retail rates in the US. Service and country can change the rule.
FedEx - Dimensional Weight
How FedEx calculates dimensional weight
FedEx uses a 139 divisor for US domestic parcel services. Confirm the current tariff before quoting a shipment.
USPS - Dimensional Weight
When USPS applies dimensional weight
USPS uses a 166 divisor and applies dimensional weight to specified services and sizes. Not every parcel is affected.
References identify the method or data behind this calculator. Where a standard or tariff changes, the current edition applies, and the assumptions stated above take precedence over a remembered figure.
Frequently Asked Questions
Why is my parcel billed at a higher weight than I measured?
The carrier is charging for the space the carton occupies, not just its mass. A large box filled mostly with air still takes up room in a van or aircraft. Reducing the carton size is often the fastest way to lower the bill.
Which divisor should I use?
Match the carrier and service on your label. In the US, UPS and FedEx daily rates use 139, retail rates and USPS use 166, and metric air tariffs commonly use 5,000 or 6,000. The divisor is a commercial term, so confirm it in the current tariff rather than assuming it never changes.
Does dimensional weight apply to every parcel?
No. Carriers apply it to specific services and above certain sizes, and some small or flat-rate services are exempt. The calculator always shows the comparison, so you can see whether dimension actually governs for the entered profile.
How do carriers round the result?
Most round up to the next whole pound or kilogram, and some apply a minimum billable weight. This calculator shows the exact figure so you can see how close the parcel is to the next step, then check the carrier rule for the service you are using.
How can I reduce dimensional weight?
Use the smallest carton that protects the product, remove void fill where a shorter box will do, and consider a poly mailer for soft goods. Do not trade protection for size: a damaged parcel costs more than the weight difference.