How to calculate landed cost per unit
Include inbound freight and other inventory acquisition costs in unit economics.
Read guide →Free shipping calculator · Instant estimate
Shipping & Dimensional Weight Calculator
Compare actual package weight with dimensional weight to estimate the billable weight carriers may use. Adjust the divisor and rounding rules to match your service.
Enter your package details
Use the outside dimensions of the fully packed parcel.
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Measurement units
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Package dimensions
Outside measurements
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Carrier divisor & rounding
The divisor is expressed as in³ per lb when using inches/pounds, or cm³ per kg when using centimeters/kilograms. Contracted rates and service rules can differ.
What this estimate does: calculates package volume, dimensional weight and the greater of dimensional or actual weight. It does not calculate postage, surcharges, delivery time or carrier eligibility.
How dimensional weight works
Carriers may charge based on the space a parcel occupies rather than its scale weight. Dimensional weight is calculated by multiplying the package length, width and height, then dividing by the carrier or service divisor. The estimated billable weight is generally the greater of actual weight and dimensional weight.
Worked example: an 18 × 14 × 12 inch box
With a 139 divisor, the parcel volume is 3,024 cubic inches. Dividing by 139 gives 21.76 lb of dimensional weight. If the actual parcel weighs 8 lb and the selected setting rounds billable weight up, the estimated billable weight is 22 lb.
Why the divisor matters
Divisors and rounding methods vary by carrier, service, rate type, shipment lane and negotiated contract. UPS publishes different divisors for Daily and Retail rates; FedEx describes dimensional-weight calculations for U.S. shipments. Always confirm the current rule for the exact label or service before purchasing postage.
How to reduce dimensional shipping costs
- Measure the outside of the fully packed parcel, including bulges and protective packaging.
- Choose the smallest safe box or mailer that protects the product.
- Compare several package sizes before committing to packaging inventory.
- Use the divisor and rounding method from your carrier account or negotiated shipping agreement.
Official references: UPS package dimensions and weight · FedEx dimensional weight.
Margenao provides an independent estimate, not a carrier quote. Actual charges may include minimum billable weights, additional handling, oversize fees, dimensional thresholds, fuel surcharges and account-specific rules.
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