Free DIM Weight Calculator

Calculate dimensional weight for UPS, FedEx, and USPS. Find out if your boxes are costing more than they should.

DIM Weight Calculator

Enter your package dimensions to see if you are overpaying on shipping.

in / lbscm / kg

What Is Dimensional Weight (DIM Weight)?

Dimensional weight -- also called DIM weight, volumetric weight, or cubed weight -- is a pricing technique used by all major shipping carriers including UPS, FedEx, and USPS. Instead of charging solely by how much a package weighs, carriers also account for how much space it occupies on the truck.

The concept is straightforward: carriers have limited cargo space. A large, lightweight box takes up room that could hold heavier, more profitable packages. DIM weight pricing ensures carriers are compensated for the space a package uses, not just its mass.

For D2C brands, DIM weight is one of the most common sources of hidden shipping costs. If your box is even a few inches larger than necessary in each dimension, the compounding effect on DIM weight can increase your billed weight by 2-5x -- and you will never see "DIM surcharge" on an invoice. It is silently baked into your per-package shipping rate.

The DIM Weight Formula

DIM Weight (lbs) = (L x W x H) / DIM Factor

UPS / FedEx

DIM Factor: 139

USPS Priority

DIM Factor: 166

Dimensions are measured in inches (exterior measurements of the package). The result is rounded up to the next whole pound. For metric measurements, the equivalent formula uses centimeters with a DIM factor of 5,000.

Example: A box measuring 14" x 12" x 8" has a volume of 1,344 cubic inches. Divided by 139 (UPS/FedEx), that is 9.7 lbs DIM weight. If your product weighs 3 lbs, you are billed for 10 lbs -- more than 3x the actual weight.

DIM Factors by Carrier (2026)

CarrierDIM FactorApplies To
UPS139All domestic services
FedEx139All domestic services
USPS Priority166Priority Mail (over 1 cu ft)

International shipments may use different DIM factors. High-volume shippers can often negotiate custom DIM divisors with their carrier rep.

How to Reduce DIM Weight Charges

1. Right-size your boxes

Most D2C brands use 2-3 box sizes for all products. Adding 1-2 more sizes that fit your best sellers tightly can eliminate 30-50% of DIM overpay. Use the calculator above to find your target cubic volume.

2. Switch to poly mailers

If your product is not fragile, poly mailers and padded envelopes are billed by actual weight only. This completely eliminates DIM charges.

3. Negotiate your DIM divisor

If you ship 500+ packages/month, ask your UPS or FedEx rep for a higher DIM divisor. Moving from 139 to 166 reduces DIM weight by ~16% on every package.

4. Audit your full packaging supply chain

DIM weight is just one of 12+ margin leaks in your packaging supply chain. A full packaging cost audit identifies supplier pricing drift, MOQ penalties, freight markups, and more.

DIM Weight FAQ

What is DIM weight (dimensional weight)?+
DIM weight is a pricing method used by shipping carriers that accounts for the space a package occupies rather than just its actual weight. It is calculated as (Length x Width x Height) divided by a DIM factor (139 for UPS/FedEx, 166 for USPS Priority). Carriers charge whichever is greater: the actual weight or the DIM weight.
What is the DIM factor for UPS and FedEx?+
The DIM factor for both UPS and FedEx is 139 for domestic US shipments as of 2026. This means you divide the cubic size of your package (L x W x H in inches) by 139 to get the dimensional weight. High-volume shippers can sometimes negotiate a higher divisor to reduce DIM charges.
How can I reduce DIM weight charges?+
The most effective ways are: right-size your boxes, switch to poly mailers for non-fragile items, reduce void fill with custom inserts, negotiate your DIM divisor with your carrier, and use regional carriers with more favorable DIM pricing.
What is the DIM weight formula?+
DIM Weight (lbs) = (Length x Width x Height in inches) / DIM Factor. For UPS/FedEx the DIM factor is 139. For USPS Priority it is 166. In metric: DIM Weight (kg) = (L x W x H in cm) / 5,000.
Does USPS charge by DIM weight?+
Yes, USPS charges by DIM weight for Priority Mail packages that exceed 1 cubic foot (1,728 cubic inches). The USPS DIM factor is 166, which is more favorable than UPS/FedEx. USPS First Class and Ground Advantage have their own size/weight limits but generally do not use DIM pricing the same way.

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