Calculation Methodology
This document explains how DIM Weight Calculator computes billable weight for each carrier.
⚠️ 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 Ground & Express
| Parameter | Value |
|---|---|
| DIM Divisor | 139 (in³/lb) |
| Dimension Rounding | Round UP to next whole inch |
| Billable Weight | Ceiling of max(actual, DIM) |
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
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
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
Prior to ~2015, many carriers used a DIM divisor of 166 for domestic shipments. The industry has largely standardized on 139 (imperial) and 5000 (metric). Some regional or legacy services may still use different divisors.
Questions?
See our FAQ on the homepage or contact us.