As of January 27, 2019, the USPS is raising their rates.
First class pricing is going to be figured by zones, like priority mail is. Currently, first class shipping cost is only based on the weight of the package. For example, if a package weighs 4 ounces it’s going to cost $2.66 whether it’s going to Maine or California. Because the new rates will be based on the weight and the zone, the farther away the package is going, the more it will cost.
First Class rates:
Priority Cubic rates: (shoebox size or less)
Length x Width x height / 1728 = cubic feet (Max of 18″ in any dimension)
Priority by weight:
Priority Flat rate:
First class and Priority cubic are always the cheapest way to go if your package qualifies.