Dimensional Weight Calculator

UPS, FedEx, Amazon MCF/FBA & Walmart WFS

Published US domestic divisor (inches and pounds). UPS Daily Rates, FedEx, Amazon MCF/FBA, and Walmart WFS all bill the greater of actual weight and L × W × H ÷ 139.

USPS (packages over 1 cubic foot)

USPS aligned its divisor to 139 on July 12, 2026 for Priority Mail Express, Priority Mail, Ground Advantage, and Parcel Select. Dimensional weight still applies only when cubic volume is greater than 1,728 in³ (1 cubic foot).

Legacy / negotiated 166

Former USPS divisor and the figure still used on some UPS retail counter rates and negotiated contracts. Included so you can compare against older planning assumptions.

How measurements are rounded

• UPS, FedEx, and USPS round each side up to the next whole inch before multiplying (a 12.1 in side becomes 13 in)
• Dimensional weight is then rounded up to the next whole pound. Actual scale weight is typically rounded the same way
• International express often uses centimetres and kilograms with a 5,000 divisor, and may round chargeable weight to the next 0.5 kg

What still differs by program

• USPS still skips dimensional weight on packages at or under 1 cubic foot (1,728 in³)
• Walmart WFS adds a 0.25 lb packaging allowance after comparing unit and dimensional weight
• Amazon MCF small-standard units are billed on unit weight only; other size tiers use the greater of unit and dimensional weight
• High-volume contracts may still specify 166 or another negotiated divisor

What the calculator includes

• Cubic volume from the three sides you enter, with optional round-up of each side
• Dimensional weight as L × W × H ÷ divisor, using the published factors listed above
• Billable weight as the greater of rounded actual weight and rounded dimensional weight
• The USPS one-cubic-foot threshold when that preset is selected

Sources: Amazon MCF rate card, Walmart WFS pricing, UPS dimensional weight, FedEx dimensional weight, USPS DMM dimensional weight, DHL volumetric weight.

What it excludes

• Postage, zone rates, and fuel surcharges
• Oversize, additional-handling, and residential delivery fees that also key off dimensions
• WFS's 0.25 lb packaging allowance and Amazon small-standard exceptions
• Account-specific or negotiated divisors unless you enter them as a custom value

What is dimensional weight?

Dimensional weight (also called volumetric weight) prices a carton by the space it occupies, not just the number on a scale. Carriers calculate it as length × width × height divided by a published divisor, then charge the greater of that result and the actual weight.

Which divisor should I use?

For US domestic parcels in 2026, UPS Daily Rates, FedEx, USPS, Amazon MCF/FBA, and Walmart WFS all publish 139 when dimensions are in inches and weight is in pounds. Use 166 only if you are modeling a legacy assumption or a negotiated contract that still specifies it. International express commonly uses 5,000 when dimensions are in centimetres and weight is in kilograms.

Did USPS change its dimensional weight formula?

Yes. On July 12, 2026, USPS lowered its divisor from 166 to 139 and began rounding each fractional inch up to the next whole inch, matching UPS and FedEx. USPS still applies dimensional weight only to packages larger than one cubic foot (1,728 cubic inches).

How does rounding work?

Most US carriers now round each side up to the next whole inch before multiplying, then round the resulting dimensional weight up to the next whole pound. Actual scale weight is typically rounded the same way. Billable weight is the greater of those two rounded figures.

How can I lower dimensional weight?

Use a smaller carton, cut void fill, and avoid shipping air. Because every extra inch is multiplied across the other two sides, a box that is only slightly oversized can jump a full billable pound. Fulfillment programs that pick the smallest fitting carton reduce dimensional weight on every order.