Dimensional Weight Calculator

Understanding Volumetric Weight in Shipping

Courier companies measure profitability not just by pounds but by cubic feet. A large, lightweight package—like a foam-filled box or inflatable product—wastes truck space even though it weighs little. To account for this, carriers introduced volumetric weight in 2015. When a package's dimensional weight exceeds its actual weight, the carrier charges based on dimensional weight instead.

Each major carrier applies its own divisor (often called the "DIM factor") to the volume formula. This means the same package can have three different billable weights depending on which carrier you use. Savvy shippers measure their packages and run the math before committing to a carrier.

How to Calculate Dimensional Weight

Dimensional weight uses a straightforward formula. Measure length, width, and height, multiply them together, then divide by the carrier's divisor. Each carrier's DIM factor reflects their truck capacity and pricing model.

• Length — Package length in inches or centimeters
• Width — Package width in inches or centimeters
• Height — Package height in inches or centimeters
• DIM factor — Carrier-specific divisor (139, 166, or 5000 depending on carrier and unit system)

Carrier-Specific Dimensional Weight Rules

UPS distinguishes between daily account holders and occasional retail shippers. Account customers get a 139 divisor, while retail customers use 166. For metric measurements, UPS applies a 5000 divisor.

FedEx uses 139 for imperial units (inches and pounds) and 5000 for metric units (centimetres and kilograms). Maximum package weight is 150 lbs or 70 kg. FedEx charges whichever is greater: actual weight or dimensional weight.

USPS changed its policy in mid-2019, moving from a 194 divisor to 166. One advantage: USPS ignores dimensional weight for packages under one cubic foot. However, USPS has a strict 70-pound maximum actual weight limit.

Real-World Example: Comparing Carriers

Suppose you ship a lightweight but bulky item measuring 70 × 14 × 14 inches.

Volume: 70 × 14 × 14 = 13,720 cubic inches

• FedEx DIM weight: 13,720 ÷ 139 = 98.7 lbs (rounds to 99 lbs)
• UPS (retail): 13,720 ÷ 166 = 82.7 lbs (rounds to 83 lbs)
• USPS: 13,720 ÷ 166 = 82.7 lbs (rounds to 83 lbs)

UPS and USPS would charge the same dimensional weight here, but your final cost depends on distance zones and service tier. Always compare rate cards after calculating dimensional weight.

Practical Tips for Managing Dimensional Weight

Reduce shipping costs and avoid surprises by following these proven strategies.

1. Measure accurately and round up — Carriers round up fractional inches. A 10.2-inch dimension counts as 11 inches. Measure to the furthest points of your package, including any protruding edges or flaps that add to the footprint.
2. Use compact, dense packaging — Choose boxes that fit your product snugly rather than leaving excess air space. Foam peanuts and air pillows inflate volume unnecessarily. Consider flat-rate shipping for small, heavy items where dimensional weight won't apply.
3. Check weight and size limits before shipping — USPS caps packages at 70 lbs actual weight. FedEx and UPS allow up to 150 lbs. Oversized fees also kick in if length plus girth exceeds 130 inches—these compounds your costs beyond dimensional weight alone.
4. Compare carriers for your specific shipment — Run the same package dimensions through all three carriers' calculators. The cheapest option varies by shipment profile. High-volume shippers might negotiate better DIM factors or switch carriers based on seasonal demand.