Methodology and sources
How every number on this site is calculated, and where the rules come from.
Updated 2026-09-30
Dimensional weight
- Inputs are converted into the carrier's billing units (inches and pounds for US carriers, centimetres and kilograms for international express).
- Where the carrier rounds, each side is rounded up to the next whole unit.
- Length × width × height is divided by the carrier's divisor and rounded up to the carrier's billing increment.
- If the carrier has a size threshold (USPS: 1 cubic foot), dimensional weight is skipped below it.
- Billable weight is the greater of dimensional weight and actual weight, both rounded up.
Carrier rules in use
- USPS: divisor 139 cu in/lb, sides rounded up, only above 1,728 cu in, weight rounded up to the next lb. DCL: USPS DIM weight changes, July 12 2026 · Ordoro: USPS shipping changes 2026
- UPS (Daily Rates): divisor 139 cu in/lb, sides rounded up, weight rounded up to the next lb. ParcelPath: UPS dimensional weight
- UPS (Retail Rates): divisor 166 cu in/lb, sides rounded up, weight rounded up to the next lb. ParcelPath: UPS dimensional weight
- FedEx: divisor 139 cu in/lb, sides rounded up, weight rounded up to the next lb. FedEx: how to calculate DIM weight
- DHL Express (International): divisor 5000 cm³/kg, sides as measured, weight rounded up to the next 0.5 kg. Wikipedia: Dimensional weight
Carriers also add surcharges this site does not model: additional handling, oversize and large package fees, residential and delivery-area charges, and fuel. Negotiated contracts can change the divisor; use the custom divisor option for yours.
CBM and containers
- Carton volume = length × width × height in centimetres ÷ 1,000,000. 1 m³ = 35.3147 cu ft.
- Container volume uses typical ISO internal dimensions. Builders vary by a few centimetres.
- Usable volume = internal volume × packing efficiency (85% by default, adjustable).
- Containers needed = the larger of total volume ÷ usable volume and total weight ÷ typical payload, rounded up.
- “Stacked” counts use a uniform grid in the best of six orientations. They do not model pallets, mixed orientations or crush limits.
Limits
Results are estimates for planning. Your carrier invoice or freight booking is the final word. If you find a rule that has changed, email hello@billedweight.com and we will update it.