cheapest way to send boxes depends on various factors such as package size, weight, and destination. For smaller boxes, USPS First-Class Mail is often the most affordable option, especially for lightweight items. For heavier boxes, USPS Priority Mail, UPS Ground, or FedEx Ground may provide the most cost-effective rates depending on the distance and size of the package. Additionally, using flat-rate boxes from USPS can sometimes save money when shipping heavier items, as the price remains the same regardless of weight. Comparing different shipping carriers and services can help businesses and consumers find the cheapest way to send boxes while ensuring timely delivery.