What is dimensional weight?
Dimensional weight (also called DIM weight or volumetric weight) is a pricing method carriers use to charge by the space a package occupies rather than its actual weight. A truck or aircraft fills up by volume long before it hits a weight limit, so carriers protect their revenue by billing whichever is greater: actual weight or dimensional weight.
That means a 2 kg box of pillows can be billed as if it weighed 12 kg — because it's bulky. For e-commerce shippers moving apparel, foam, or lightweight goods, DIM weight can inflate invoices by 30% or more.
How is dimensional weight calculated?
The formula every major carrier uses:
DIM weight = (Length × Width × Height) ÷ DIM divisor
Measured in inches, rounded up to the next whole pound.
The DIM divisor is the key variable. Lower divisor = higher cost. Standard published divisors:
| Carrier | US Domestic Divisor | International Divisor |
|---|---|---|
| FedEx | 139 | 139 |
| UPS | 139 | 139 |
| DHL Express | 139 (5000 metric) | 5000 (cm/kg) |
| USPS | 166 (over 1 cu ft) | 166 |
Worked example: A 20" × 16" × 12" box weighing 8 lb actual.
Volume = 3,840 cu in ÷ 139 = 27.6 → 28 lb billable. You pay for 28 lb, not 8 lb. That's a 3.5× markup.
7 ways to avoid dimensional weight charges
1. Right-size your packaging
The single biggest lever. Every cubic inch of empty space is billed air. Use boxes that fit the product with minimal void. Cutting a 20×16×12 box down to 16×12×8 drops billable weight from 28 lb to 12 lb — a 57% reduction.
2. Switch to poly mailers for soft goods
Apparel, textiles and non-fragile soft goods don't need boxes. Poly mailers conform to the product, often dropping below the DIM threshold entirely and billing on actual weight.
3. Eliminate oversized void fill
Swap bulky bubble wrap and foam blocks for right-sized inflatable pillows or paper. Less void means smaller boxes means lower DIM.
4. Negotiate a higher DIM divisor
High-volume shippers can negotiate divisors of 150, 166, or higher directly with carriers — or access pre-negotiated divisors through a freight broker. A divisor bump from 139 to 166 cuts DIM weight by 16% on every package.
5. Compare carriers per shipment
Divisors and thresholds differ. USPS doesn't apply DIM weight to packages under one cubic foot; DHL's international metric divisor behaves differently than FedEx. The cheapest carrier changes shipment to shipment. A multi-carrier rate calculator surfaces the lowest DIM-adjusted price instantly.
6. Audit your packaging catalog quarterly
Product mixes change. A box that was right-sized last quarter may now ship half-empty. Quarterly audits catch creeping DIM costs before they compound.
7. Use a broker's contract rates
Beyond divisors, the underlying rate matters. Contract-tier pricing from a freight broker stacks on top of DIM optimization — so even when DIM applies, the per-pound rate is 30–62% lower than retail.
How much can you actually save?
Combining right-sized packaging, a negotiated divisor, and contract rates typically cuts total shipping spend by 25–40% for DIM-heavy catalogs. AVIO's free freight audit models your exact savings across all four carriers before you change anything.
See your DIM-adjusted rate in seconds.
Compare FedEx, DHL, UPS and USPS pricing — DIM weight included, no surprises.
Calculate my rateFrequently asked questions
What is dimensional weight in simple terms?
It's the carrier charging you for how much space your package takes up, not how heavy it is — because a big light box wastes valuable cargo room.
Which carrier has the best DIM divisor?
USPS is most forgiving (no DIM under 1 cubic foot, 166 divisor above). But the best total price depends on lane, weight and destination — always compare.
Does dimensional weight apply to international air freight?
Yes. International air freight uses volumetric weight universally (commonly a 6000 cm³/kg or 5000 cm³/kg divisor). It often matters more internationally than domestically.