Calculation Methodology

This document explains how DIM Weight Calculator computes billable weight for each carrier.

Carrier references reviewed July 14, 2026.

The formulas below describe DIMCalc's implementation. They are not a promise that every carrier service, account, country, or rate type uses the same divisor or rounding rule.

⚠️ Disclaimer

Carrier rules may vary by service type, account agreements, and country. Always verify with official carrier calculators before shipping.

What is Dimensional Weight?

Dimensional weight (DIM weight) is a pricing technique used by shipping carriers. It calculates a theoretical weight based on package volume, ensuring large but lightweight packages are charged fairly relative to the space they occupy.

Billable weight is the greater of actual weight or DIM weight.

UPS Daily Rates (calculator scope)

Parameter	Value
DIM Divisor	139 (in³/lb)
Dimension Rounding	Round UP to next whole inch
Billable Weight	Ceiling of max(actual, DIM)

UPS currently publishes a divisor of 139 for Daily Rates and 166 for Retail Rates. DIMCalc models Daily Rates only; use the official UPS rate tool for Retail Rates.

UPS Formula

DIM Weight (lb) = (⌈L⌉ × ⌈W⌉ × ⌈H⌉) ÷ 139
Billable (lb) = ⌈max(Actual, DIM)⌉

UPS Example

Package: 11.1" × 8.1" × 4.1", Actual: 3.2 lb

Rounded dimensions: 12" × 9" × 5" = 540 in³
DIM weight: 540 ÷ 139 = 3.88 lb
Billable: ⌈max(3.2, 3.88)⌉ = 4 lb

Official UPS Documentation →

FedEx Ground & Express

Parameter	Value
DIM Divisor	139 (in³/lb)
Dimension Rounding	Round UP to next whole inch
Billable Weight	Ceiling of max(actual, DIM)

FedEx Formula

DIM Weight (lb) = (⌈L⌉ × ⌈W⌉ × ⌈H⌉) ÷ 139
Billable (lb) = ⌈max(Actual, DIM)⌉

FedEx Example

Package: 12" × 10" × 8", Actual: 5 lb

Volume: 12 × 10 × 8 = 960 in³
DIM weight: 960 ÷ 139 = 6.9 lb
Billable: ⌈max(5, 6.9)⌉ = 7 lb

Official FedEx Documentation →

DHL Express

Parameter	Value
DIM Divisor	5000 (cm³/kg)
Dimension Rounding	Standard rounding to whole cm
Billable Weight	Round UP to next 0.5 kg

DHL Formula

DIM Weight (kg) = (round(L) × round(W) × round(H)) ÷ 5000
Billable (kg) = ceilToHalf(max(Actual, DIM))

DHL Example

Package: 76 × 40 × 40 cm, Actual: 20 kg

Volume: 76 × 40 × 40 = 121,600 cm³
DIM weight: 121,600 ÷ 5000 = 24.32 kg
Billable: ceilToHalf(24.32) = 24.5 kg

Official DHL Documentation →

Canada Post / Postes Canada

Canada Post uses Volumetric Equivalent (VE) instead of "DIM weight". The divisor varies by service type.

Service	Divisor (metric)	Divisor (imperial)
Priority™, Xpresspost™, Expedited Parcel™, US/Intl	5000 (cm³/kg)	139 (in³/lb)
Regular Parcel™	6000 (cm³/kg)	166 (in³/lb)

Parameter	Value
Dimension Rounding	Standard rounding to whole cm
Chargeable Weight	Round UP to next 0.5 kg
Minimum Tier	0.75 kg for many services (exceptions exist)

Canada Post Formula

VE (kg) = (round(L) × round(W) × round(H)) ÷ divisor
Chargeable (kg) = ceilToHalf(max(Actual, VE))
If max ≤ 0.75 kg: Chargeable = 0.75 kg (min tier)

Canada Post Example 1 (Priority — divisor 5000)

Package: 100 × 60 × 20 cm, Actual: 8 kg

Volume: 100 × 60 × 20 = 120,000 cm³
VE: 120,000 ÷ 5000 = 24 kg
Chargeable: max(8, 24) = 24 kg

Canada Post Example 2 (Regular Parcel — divisor 6000)

Package: 100 × 60 × 20 cm, Actual: 26 kg

Volume: 100 × 60 × 20 = 120,000 cm³
VE: 120,000 ÷ 6000 = 20 kg
Chargeable: max(26, 20) = 26 kg

Note: Canada Post rules may vary by specific service, destination, and account. Some services have exceptions to the 0.75 kg minimum and the 0.5 kg rounding. Always verify with official Canada Post tools.

Official Canada Post VE Documentation →
Official Canada Post Pricing Documentation →

Unit Conversions

Conversion	Factor
Inches to Centimeters	1 in = 2.54 cm
Pounds to Kilograms	1 lb = 0.45359237 kg

Historical Notes

Divisors are service- and rate-specific. UPS still publishes 166 for Retail Rates, while its Daily Rates use 139. Other carriers and regional services may use different factors.

Questions?

See our FAQ on the homepage or contact us.