Dimensional Weight Calculator
Carriers charge the greater of actual weight and dimensional (volumetric) weight — and each carrier uses a different divisor. Pick the service, enter the box, and see the billable weight that decides your bill. Inputs stay in the URL — bookmark the box.
L × W × H — the outer carton, not the product.
Divisor: lb · ÷139 (in³/lb)
Billable weight
52.68 lb≈ 23.90 kg
→ Billed on DIMENSIONAL weight (box is light for its size)
// Amazon US FBA
dim = (L×W×H in) ÷ 139 = 52.68 lb
billable = max(dim, actual) = 52.68 lb
Selling on Amazon? The size tier — not just the weight — sets your FBA fee.
The FBA calculator maps your box to the 2025 size tier and estimates the fulfillment fee — where shrinking a dimension can drop a whole tier.
Open the FBA size & fee calculatorHow dimensional weight is calculated
Carriers do not want to fly air. A big, light box takes the space of a heavy one, so they bill the greater of two numbers — actual weight, and a weight worked out from volume. Here is the whole method.
1. Measure the outer carton
Length × width × height of the packed box, including any bulge. Round each up to the carrier's unit (most round to the next whole cm or inch).
2. Multiply, then divide by the carrier divisor
Volume ÷ divisor gives dimensional weight. The divisor encodes the carrier's assumed density: 5,000 cm³/kg for most express, 6,000 for IATA air, 139 in³/lb for Amazon FBA and US domestic.
3. Compare with actual weight — bill the greater
Billable weight = max(dimensional, actual). If dimensional wins, your box is "light for its size" and shrinking it saves money. If actual wins, you are paying for real mass.
| Service | Divisor | Formula |
|---|---|---|
| Amazon US FBA | 139 | (L×W×H in) ÷ 139 = lb |
| UPS / FedEx US domestic | 139 | (L×W×H in) ÷ 139 = lb |
| UPS / FedEx / DHL express | 5,000 | (L×W×H cm) ÷ 5000 = kg |
| Air freight (IATA) | 6,000 | (L×W×H cm) ÷ 6000 = kg |