Empty envelopes less than 20 grams, even a few grams, are calculated according to the tariff of 20 grams.

Then if it exceeds 20g, that is, from 2 1 g, every 20g counts as 1.2 yuan until it reaches100g, and the charge for every 20g 1.2 yuan is continuous weight.

If it exceeds 100g, every 100g 2 yuan, this is another continuous charging method.

Strictly speaking, the letter charge of 20.000 1g and 39.9999g is the same.