Inch ↔ cm conversion and measuring tips?

1 inch = 2.54 cm. Many services require whole-unit (or rounded-up) measurements. Check your chosen service’s current rounding rules: FedEx · UPS · DHL · USPS .

Why do I see 139, 166, 5000, or 6000?

They’re different systems/contexts: 139 (in/lb) is common for express parcels (USPS sometimes 166 ); 5000 is common in cm/kg ; 6000 (or CBM × 167 ) is frequent in airfreight. Follow the rules for your selected carrier/service ( IATA overview ).

Is DIM weight used for every package?

Not always. The chargeable weight is the larger of actual vs DIM. Oversize/overlength fees may also apply depending on the service (see your carrier’s page above).

Dimensional Weight Explained for International Shipping

Dimensional weight determines the chargeable weight when it’s greater than actual weight. This guide explains the formulas (139/166/5000/6000), shows quick worked examples, compares carrier standards (FedEx/UPS/DHL/USPS/IATA), and gives practical tips to reduce DIM. Use our Shipping Calculator to test box sizes before you ship and check live price tiers on the Pricing page.