Accuracy and Methodology
DutyGlobal uses deterministic formulas and published industry standards to generate structured cost estimates.
This page explains how each calculator works and outlines factors that may cause differences between our estimates and your final charges.
Dimensional Weight
The Dimensional Weight Calculator converts package dimensions into volumetric weight using standard carrier formulas.
Formula:
Dimensional Weight = (Length × Width × Height) ÷ Divisor
Metric system
- Dimensions in centimetres (cm)
- Standard divisor: typically 5000
- Result expressed in kilograms (kg)
Imperial system
- Dimensions in inches (in)
- Standard divisor: typically 139
- Result expressed in pounds (lbs)
Important notes:
- The divisor varies by carrier and service level.
- DutyGlobal uses commonly published standard divisors unless otherwise specified.
- Results are rounded according to common carrier billing practices (typically rounding up to the nearest 0.5 kg or 1 lb).
CBM (Cubic Metres)
The CBM Calculator computes shipment volume using standard geometric formulas.
Formula (metric):
CBM = (Length × Width × Height in cm) ÷ 1,000,000
For multi-piece shipments:
- Each package volume is calculated individually
- Volumes are summed to produce the total CBM
Imperial dimensions are converted to metric before calculation:
- 1 inch = 2.54 cm
Accuracy depends entirely on the dimensions entered.
Chargeable Weight
Carriers typically price shipments based on the higher of actual (gross) weight or dimensional weight.
Formula:
Chargeable Weight = max(Gross Weight, Dimensional Weight)
For multi-piece shipments:
- Each piece is evaluated individually
- The chargeable weight of each piece is summed
The divisor used for dimensional weight depends on the selected carrier and unit system.
Landed Cost
The Landed Cost Calculator estimates total import cost based on user inputs and publicly available tariff and tax rules.
General formula:
Landed Cost = Product Cost + Freight + Insurance + Duty + Tax + Additional Fees
Key principles:
- Duty is calculated as a percentage of the customs value (which may vary depending on Incoterms and valuation rules).
- VAT/GST/Sales Tax is typically applied to customs value plus duty (depending on jurisdiction).
- De minimis thresholds are applied where applicable; below the threshold, duty and/or tax may be waived.
- Optional fields allow users to include freight, insurance, and other costs for a more comprehensive estimate.
Exact customs valuation rules vary by country and may include additional adjustments.
What Can Cause Differences vs. Final Charges
Even with accurate inputs, actual charges may differ due to:
- HS code reclassification — Customs authorities may assign a different tariff code.
- Customs valuation adjustments — Declared values may be revised under local valuation rules.
- Exchange rate differences — Customs authorities often use official reference rates.
- Carrier rounding policies — Some carriers round differently than standard public rules.
- Contract-specific divisors — Negotiated shipping contracts may use different dimensional divisors.
- Additional government fees — Certain jurisdictions impose processing, inspection, or harbour fees.
- Brokerage and handling charges — Service fees from customs brokers or forwarders.
- Regulatory changes — Tariff rates, tax rules, and thresholds may change between estimate and clearance.
Our Commitment
DutyGlobal reviews tariff data, tax rules, and carrier policies on a periodic basis.
Each calculator displays:
- The formula used
- The divisor applied
- The unit system selected
- The last review date (where applicable)
If you identify a discrepancy, please contact us at support@dutyglobal.com so we can investigate.
Important
DutyGlobal provides structured estimates to support planning and decision-making.
Estimates only. Always confirm final charges with your carrier, freight forwarder, or customs broker.
Last updated: 2026-02-12