Outbound transportation costs per unit tend to be lower than inbound costs,because inbound lot sizes are typically larger.

Inbound Costs

Expenses related to the transportation, handling, and receiving of goods coming into a business.

Outbound Transportation

The process and cost associated with moving goods from a company's premises to the end customer.

Unit

Refers to a single, complete item of a product or a measure of quantity in terms of number, length, or volume in a given context.